Griffiths phase and magnetocaloric behaviour in electron doped Ca0.85Sm0.15MnO3

Accepted Manuscript Griffiths phase and magnetocaloric behaviour in electron doped Ca0.85Sm0.15MnO3 Ripan Nag, Bidyut Sarkar, Sudipta Pal PII:

S0925-8388(18)31156-3

DOI:

10.1016/j.jallcom.2018.03.279

Reference:

JALCOM 45509

To appear in:

Journal of Alloys and Compounds

Received Date: 2 January 2018 Revised Date:

9 March 2018

Accepted Date: 21 March 2018

Please cite this article as: R. Nag, B. Sarkar, S. Pal, Griffiths phase and magnetocaloric behaviour in electron doped Ca0.85Sm0.15MnO3, Journal of Alloys and Compounds (2018), doi: 10.1016/ j.jallcom.2018.03.279. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

Griffiths phase and magnetocaloric behaviour in electron doped Ca0.85Sm0.15MnO3 Ripan Nag, Bidyut Sarkar and Sudipta Pal*

*

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Department of Physics, University of Kalyani, Kalyani, Nadia 741235, W.B.,India

Author for correspondence: Dr. Sudipta Pal, e-mail: [email protected]

: 091 033 2582 8282

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Fax

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Tel No. : 091 033 2582 2505

Abstract: Magnetic and magnetocaloric properties of electron doped manganite Ca0.85Sm0.15MnO3(CSMO) synthesized by conventional solid state reaction route are studied. By Sm doping at the Ca site the long range antiferromagnetic ordering of the pristine CaMnO3 sample is disturbed and ferromagnetism is induced. The polycrystalline CSMO sample undergoes ferromagnetic to paramagnetic transition at a temperature of 115 K. In

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addition to the positive slopes of the Arrot plots, the excellent fit of the magnetization data with the Equation of state and the positive value of the Landau coefficient B(T) indicates 2nd order magnetic phase transition. The presence of the Griffiths phase (GP) was identified from

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the susceptibility study of the sample and the GP characteristic is suppressed with increasing applied magnetic field strength. Temperature dependent magnetic entropy changes for different magnetic fields have been determined using numerical integration of Maxwell's

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relation based on experimental magnetization data. The maximum magnetic entropy change is found to be 0.61 J-kg-1k-1 for a magnetic field change of 10 kOe. The magnetic entropy change curves at different applied magnetic field collapsed onto a single universal curve. This further confirms that the studied sample undergoes a 2nd order magnetic phase transition.

Keywords: A ceramics , A magnetically ordered materials, C magnetocaloric, C phase transition D magnetic measurements.

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ACCEPTED MANUSCRIPT 1. Introduction: Among different type of phase inhomogeneity, the existence of ferromagnetic clusters in paramagnetic matrix is of great interest. This gives rise to Griffiths singularity which was first introduced by R. B. Griffith [1] in order to explain the effect of quenched randomness on the magnetic behavior of diluted Ising ferromagnet where only a fraction of lattice sites

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possess magnetic moments. In the Griffiths phase regime the magnetic specimen is not purely paramagnetic and does not show long range magnetic ordering. Recently, the idea of Griffiths phase, associated with different types of disorder was used to study the magnetic behavior of manganites [2, 3]. In manganite system dilution is introduced through the impurities,

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vacancies, grain boundaries and doping of different type of atoms at different sites. Many investigations have been carried out about Griffiths phase in hole doped manganites [4-6] and

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electron doped manganites [3, 7]. Eom et al. have investigated electron doped La0.9Ce0.1MnO3 films synthesized by pulse laser deposition technique and observed Griffiths phase above the transition temperature TC [8]. Giri et al. have studied electron doped Sm0.09Ca0.91MnO3 manganite and noticed Griffiths phase which was interpreted by taking into account the modification of phase separated state due to the size reduction [9]. In electron doped La0.15−xYxCa0.85MnO3 Qian et al. [7] have pointed out that the reduction of

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shear strain effect on the Jahn-Teller splitting of MnO6 octahedra due to the decreasing tolerance factor gives rise to the development of Griffiths phase. In case of polycrystalline Sm1−xCaxMnO3 (0.80 ≤ x ≤ 0.92) strain effect and quenched disorders is supposed to be the occurrence of Griffiths phase[3]. But there are only a few investigations about the magnetic

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field dependence of Griffiths phase in polycrystalline manganite system [10, 11]. Here we have investigated the influence of the applied magnetic field on the Griffiths phase of

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Ca0.85Sm0.15MnO3 (CSMO) polycrystalline manganite. The Sm3+ ion doping in the Ca2+ site gives rise to the size mismatch which is responsible for the quenched disorder introduced in the system. In addition, this electron doped polycrystalline manganite shows magnetocaloric effect near the transition temperature. The CSMO sample also exhibits magnetic relaxation and strong intercluster magnetic interaction. So an investigation on the temperature dependence of magnetic entropy change ∆SM at different magnetic fields is also carried out and finally it has been correlated with intercluster magnetic interaction.

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ACCEPTED MANUSCRIPT 2. Experimental The CSMO polycrystalline sample has been synthesized by solid state reaction method. The precursor materials CaO, Sm2O3, Mn(CH3COO)2,4H2O were mixed in proper stoichiometric ratio and calcined at 600 °C for 6h. The product obtained after calcination was grounded properly and heated at 900°C for 12h. This calcined powder was reground, pressed into

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pellets and sintered at 1100°C for 12h. Ultimately, the pellets were sintered at 1300 °C for 12h and subsequently cooled down to the room temperature. The phase purity of the prepared sample was characterized by powder X-ray diffraction (XRD) techniques using Philips diffractometer with CuKα radiation. The Rietveld refinement of the XRD data with

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FULLPROF program confirms single phase orthorhombic perovskite structure of the prepared sample with space group Pnma. The magnetization measurement was performed

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using VSM (3T) from Cryogenic Ltd., U.K. The sample was constructed in the form of a square cuboid with dimensions 3.7 mm 3.7 mm 1.6 mm and the magnetic field was applied perpendicular to the square surface i.e. along the 1.6 mm side. Demagnetization correction is required to explain the magnetization curves of the magnetocaloric materials [12, 13]. Based on A. Aharoni's formula for the geometry of a rectangular prism we have calculated the demagnetization factor (ND / 4 π ) to be 0.235 [14]. The corresponding Hint = Hext - NDM [15].

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demagnetization correction is made to calculate the internal magnetic field using the formula

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3. Results and Discussion:

The powder X-ray diffraction pattern of the polycrystalline CSMO sample is well described by orthorhombic crystal system with space group Pnma and is shown in fig. 1. The refined

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lattice parameters, atomic positions and discrepancy factors are given in table 1. From table 1 it is clear that b / 2 < a < c . This indicates that the CSMO sample possess O'-orthorhombic phase in which the cooperative Jahn-Teller effect leads to cooperative orbital ordering [16]. Fig. 2 shows the temperature dependence of magnetization of the CSMO sample for a range of applied magnetic fields from 1 to 10 kOe. These dc magnetization data have been collected in the FC configurations. The sample undergoes ferromagnetic (FM) to paramagnetic (PM) phase transition with a characteristic Curie temperature TC of about 115 K. With the increase of the magnetic field strength the spin alignment in the field direction increases and magnetization is increased. At very low temperature, with decreasing temperature the

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ACCEPTED MANUSCRIPT magnetization increases very rapidly. The sharp increase of magnetization at low temperature is prominent at low applied magnetic field and this behavior reduces with increasing magnetic field. This increase of magnetization in the low temperature region is due to the spin alignment in the field direction. At higher magnetic field the spin alignment increases at comparatively higher temperature and this leads to the reduction of sharp increase of

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magnetization in the low temperature region. In the inset of fig. 2 we have plotted dM/dT versus T curves for H = 1, 2, 4, 6, 8 and 10 kOe. Each of the dM/dT versus T plots shows sharp minimum at about 115K which is taken as the Curie temperature of CSMO sample. The pristine sample CaMnO3 is a paramagnetic insulator at high temperature and becomes a G-

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type antiferromagnetic insulator at TN = 125 K [17]. The Sm doping at the Ca site breaks the long range antiferromagnetic ordering and induces ferromanetism in the CSMO sample.

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For the study of the magnetic field dependence of magnetization in the polycrystalline CSMO sample we have plotted M vs. H curves in the temperature range from 100K to 132K in Fig. 3. Below the transition temperature TC the magnetization increases nonlinearly with increasing applied magnetic field. Above TC the non linear behavior of magnetization versus magnetic field isotherms gradually reduces and become linear towards the room temperature. From fig 3 it is observed that the low temperature M versus H curves show small hysteresis

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which is the characteristic of a ferromagnetic material. The enlarged view of the M vs H curve at T = 10K is shown in the lower inset of fig.3 for clearly showing the low temperature hysteresis behavior and it is clear that the CSMO sample possess hysteresis behavior with coercivity field HC = 406 Oe at T = 10K. This hysteresis behavior reduces with increasing

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temperature and becomes very small above 100K. Simultaneously it is also observed that the magnetization does not saturate within the range of applied magnetic field. This might be

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attributed to the presence of some amount of AFM phase in the polycrystalline CSMO manganite [18].

The use of the Arrot plot is very convenient to determine the order of magnetic phase

transition. The Arrot plots in the temperature range of 100 to 132 k in the step of 4K is shown in the upper inset of Fig. 3. According to Banerjee's criterion [19], the Arrot plots yield negative slope for the first-order phase transition. On the contrary, for the second-order magnetic phase transition it gives positive slope. The positive slopes of the Arrot plots for our sample indicates 2nd order phase transition. The order of phase transition can be further determined by estimating the value of the Landau coefficient. The value of the Landau

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ACCEPTED MANUSCRIPT coefficient is estimated by fitting the experimental magnetization data with the equation of state given by

H = a(T )M + b(T )M 3 + c(T )M 5

(1)

where a(T), b(T), c(T) are Landau coefficients which depends on the temperature. The

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coefficient a(T) is an arbitrary constant whereas the coefficient b(T) < 0 for the first order phase transition and b(T) > 0 for the second order phase transition [20]. The coefficient c(T) may be positive or negative. In fig. 4 we have shown the fitting of the magnetization data with the equation of state and obtain the value of the coefficients as a(T) = 2283.9 Oe-g/emu,

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b(T) = 4.94 Oe-g3/emu3 and c(T) = -0.0067 Oe-g5/emu5 at a temperature of 132K. In the inset of fig. 4 we have presented the temperature dependence of Landau coefficients a(T) and b(T) and it clear that the coefficient a(T) approaches zero near TC. The value of the landau

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coefficient b(T) is positive throughout the temperature range shown in the figure. The positive value of the coefficient b(T) confirms the 2nd order nature of the phase transition. For the study of the glassy behavior of the sample we cooled the sample to 90 K in the ZFC condition and kept in this condition for 30 minutes. Then we applied the magnetic field of H = 50 Oe and started data recording. The corresponding remnant magnetization (MTRM) exponential given by [21]

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versus time (t) plot is shown in fig. 5(a). We have fitted the MTRM vs. t plot with the stressed

M TRM (t ) = M 0 − M r exp[ −(t / t0 )1− n ]

(2)

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Where M0 is the static ferromagnetic component and Mr is the glassy component responsible for the relaxation effect. The excellent fit of the magnetization data with the stressed

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exponential indicates glassiness of the polycrystalline sample. Glassy behavior means a spin glass or a cluster glass like behavior. Actually, the cluster glass may be considered as a type of spin glass [22]. The value n = 0 in equation (2) corresponds to Debye single time constant exponential relaxation and n = 1 gives no relaxation. We have obtained the value of the Mr factor as 0.24 emu/g and the fitting parameter n as 0.791. In case of Ca0.85La0.15MnO3 manganite the value of n was obtained as 0.3852 in the same measurement conditions [23]. Thus our CSMO sample shows small magnetic relaxation. In the inset of fig. 5(a) we have plotted the M vs T curves at a magnetic field of 1 kOe both for ZFC and FC configuration and clear bifurcation between FC and ZFC magnetization curves below the transition temperature TC is observed. This bifurcation may be due to glassy behavior of the polycrystalline CSMO sample. This behavior is supported by the investigation of Tong et al. 5

ACCEPTED MANUSCRIPT in case of Sm1−xCaxMnO3 (0.80 ≤ x ≤ 0.92) manganite where Tong et al. have observed bifurcation between zero field cooled and field cooled magnetization vs temperature curves and they have attributed this to spin glass or cluster glass [3]. Although there are different reasons for such bifurcation between ZFC and FC magnetization curves. For example, Khan et al. have investigated Ca0.85Pr0.15MnO3 polycrystalline manganite observed ZFC - FC state and

the AFM coupled t2g

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bifurcation. They have explained this behavior as the competition between the FM coupled eg state which leads to magnetic frustration in the

polycrystalline manganites [24]. Here we have studied further the glassy behavior of the CSMO sample by using a model originally proposed by Ulrich et al [25]. For interacting

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magnetic particles, they showed that the relaxation rate W(t) = − d/dt ( ln M(t)) shows a power law decay with exponent η which depends on density: −η

(3)

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W (t ) = A t

Here M(t) is the time dependent remnant magnetization and it is exactly the same as MTRM in equation (2). For measuring the relaxation of our sample we have cooled the CSMO sample in 10 kOe magnetic field from room temperature to 90 K and waiting for 30 minutes the field is switched off. Then remnant magnetization M(t) is measured for 104s. In fig. 5(b) we have

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plotted the decay of M (t) as a function of time and the decay of W (t) is shown in the inset of fig. 5(b). From fig. 5(b) it is clear that the magnetic relaxation is well described by the theory proposed by Ulrich et al. The Fitting of the W (t) vs t plot with equation (3) gives the value of η as 0.93 which is close to 1. This suggests that the intercluster interaction is significant in

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the CSMO sample [26].

Measurement of temperature dependent dc magnetic susceptibility at different applied

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magnetic fields exposes the presence of Griffiths phase in the CSMO sample. This is depicted in fig. 6 where inverse susceptibility shows field dependent downturn above the transition temperature on reaching from the high temperature side. Here we have plotted inverse susceptibility versus temperature curves for magnetic field H = 1 and 8 kOe. The inverse susceptibility versus temperature curves have been analysed using Curie-Weiss law:
= /( −  )

(4)

Where C denotes the Curie-Weiss constant and θCW represents the Curie-Weiss temperature. From the Curie-Weiss fitting for H = 1 and 8 kOe we have obtained the value of θCW as 92 and 100K respectively. The positive values of θCW indicates ferromagnetic interactions between spins. Again these values of θCW are lower than the value of critical temperature TC 6

ACCEPTED MANUSCRIPT = 115 K. This signifies the presence of some amount of AFM phase in the prepared CSMO sample [18]. Again, the calculated value of θCW for 8 kOe is more close to the transition temperature than that for 1 kOe. This implies that the antiferromagnetic contribution reduces with the strength of the applied magnetic field. The theoretical magnetic moment per formula

Th 2 2 µeff = 0.15µ eff ( Sm3+ ) + 0.15µeff2 ( Mn3+ ) + 0.85µeff ( Mn 4 + )

The

theoretical

values

for

the

magnetic

moments

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unit of the CSMO sample can be calculated using the following equation

are

µeff ( Sm3+ ) = 0.85µ B ,

Th µeff ( Mn3+ ) = 4.9 µ B and µeff ( Mn 4+ ) = 3.87 µ B . Using these values we obtain µeff = 4.05µ B .

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The experimental value of the effective magnetic moment can be evaluated using the relation C = N µ 2 / 3 K B where C is the Curie constant, N is the Avogadro number and KB is the

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Boltzmann constant. Using the experimental value of the Curie constant obtained from the Curie -Weiss fitting of the linear portion of the 1/χ versus T plot for H=1 kOe, we have exp = 4.52 µ B . This determined the experimental value of effective magnetic moment as µeff

comparatively larger value of effective magnetic moment indicates that short range ferromagnetic (FM) clusters contribute in the magnetization of the paramagnetic (PM) state

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of the Sample [27]. The presence of short range FM clusters in the PM state leads to the magnetic inhomogeneity in the high temperature PM state. This indicates the possibility of the existence of the Griffiths phase in the CSMO sample. Again, Curie-Weiss fitting shows that 1/χ deviates from Curie-Weiss feature as a downturn at a temperature greater than TC. magnetic field, the temperature corresponding to the onset of this

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Applying very low

downturn is determined and taken as Griffiths temperature TG and the temperature range TC ≤

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T ≤ TG is called Griffiths phase. We have obtained the value of this downturn temperature as 167K at a field of 1 kOe. Again the value of this downturn temperature reduces to 147K at 8 kOe applied magnetic field. Thus this downturn feature is suppressed with increasing magnetic field. In the theoretical work by Griffith, the Griffiths phase was observed at a magnetic field of H = 0 [1]. Thus, the more distinct nature of this downturn behavior at low applied field of H = 1 kOe is very natural. The reduction of the deviation from Curie-Weiss nature at higher magnetic field may be attributed to ordering of the spins outside the clusters and the reduced value of the downturn temperature with increasing magnetic field indicates that the Griffiths phase behaviour in CSMO sample is suppressed at high magnetic field strength.

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ACCEPTED MANUSCRIPT For the study of the field dependence of the ferromagnetically ordered regions in the paramagnetic matrix, we have used Galitski et al.'s formula for magnetization in the Griffiths phase region [28]. According to this formula the magnetization as a function of temperature and magnetic field in the Griffiths phase obeys the relation 

( , ) ∝ exp [−  ]

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(5)

where the value of the constant C' is proportional to the sum of the magnetic moments of ferromagnetically ordered cluster. We have fitted the M versus T curves in the Griffiths phase region using equation (5) for H = 1 kOe and H = 8 kOe in fig. 7. Through the fitting of the M vs T curves we have obtained the value of the constant C' as 1.431×10-2 T/K for H = 1 kOe

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and 4.172×10-2 T/K for 8 kOe. Thus, in the region of Griffiths phase the cluster size increases when the applied magnetic field is increased. Similar behavior is observed in

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La0.45Sr0.55 Mn1-xCoxO3 [10] and Ca0.85Dy0.15MnO3 [11] polycrystalline manganites. From thermodynamics, the isothermal magnetic entropy change due to the change of magnetic field can be written as [29,30],

∆ S M (T , H ) = S M (T , H ) − S M (T , 0 ) =

H m ax

∫

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0

 ∂S    dH  ∂H T

Using Maxwell's thermodynamic relation:

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 ∂S   ∂M    =   ∂H T  ∂T H

One readily obtain the equation:

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∆ S M (T , ∆ H ) =

H

m ax

∫ 0

 ∂M    dH ∂ T  H

(6)

Where S, M, H, T denote respectively the magnetic entropy, magnetization, magnetic field and temperature of the specimen. When the magnetization is measured at small discrete field and temperature intervals, the magnetic entropy change ∆SM may be calculated approximately using the expression:

∆S

M

=

∑

 ( M i − M i+1 ) H i   ∆ H Ti+1 − Ti  

i

(7)

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ACCEPTED MANUSCRIPT where Mi and Mi+1 are respectively the magnetizations at temperatures Ti and Ti+1 in a magnetic field Hi. We have plotted the magnetic entropy change ∆SM as a function of temperature at different magnetic field from 1 kOe to 10 kOe in fig. 8. With the increase of the magnetic field strength the magnitude of ∆SM increases. The Maximum values of magnetic entropy change ∆SMmax reach the values 0.073, 0.156, 0.304, 0.435,0.521 and 0.61

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J.kg -1.k -1 for magnetic field strength H = 1, 2, 4, 6, 8 and 10 kOe respectively. The increase of the magnitude of magnetic entropy change with increasing magnetic field may be attributed to the increased intercluster interaction at high magnetic field. In 8 kOe magnetic field ∆SMmax = 0.521 J.kg -1.k -1 for our CSMO sample whereas ∆SMmax = 1.126 J.kg -1.k -1 in

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Ca0.85Dy0.15MnO3 manganite in the same magnetic field [11]. This may be due to the smaller magnetic moment of Sm ion compared to Dy ion. Lu et al. have studied the La0.67Sr0.33MnO3 nano-particles and suggested that the magnetocaloric effect is reduced due to the presence of

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Griffiths phase [31]. In our polycrystalline CSMO sample the Griffith phases is suppressed at higher magnetic field. So the influence of Griffiths phase on the magnetocaloric effect is negligible at higher magnetic fields. Again from fig. 8 it is observed that the peak of ∆SM vs T plot is sharp. Sm doping in the Ca site introduces Mn3+ ion in the Ca0.85Sm0.15MnO3 sample. The double exchange interaction between Mn3+ and Mn4+ enhances ferromagnetism

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in the sample and the sharpness of ferromagnetic transition leads to sharp ∆SM peak in the sample. Similar behavior is observed in Ca0.85Dy0.15MnO3 polycrystalline manganite [11]. We can use the phenomenological universal curve of the field dependent magnetic entropy change ∆SM proposed by Franco et al. [32]. It can be utilized to determine the order of

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magnetic phase transition. In fact P. T. Phong et al. have used Franco's universal master curve to determine the order of the magnetic phase transition in case of La0.7Ca0.3MnO3

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nanoparticle system [33]. Again in case of La0.65Eu0.05Sr0.3-xMnO3 ( 0 ≤ x ≤ 0.15 ) perovskites [34] R. Bellouz et al. have used Franco's universal master curve to show that the sample undergoes 2nd order magnetic phase transition. The proposition by Franco Et al. is based on the assumption that if this type of universal curve exists then all the curves measured at different magnetic fields must merge into a single curve in case of 2nd order phase transition. The universal curve is obtained by normalizing the magnetic entropy change ∆SM with respect to the peak of the magnetic entropy change curve (∆SMmax) as a function of rescaled temperature θ. The temperature axis can be rescaled by choosing two reference temperature Tr1 and Tr2 below and above TC respectively in the following manner so that θ = ±1:

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T − TC , for T r 2 − TC

 T ≤ TC    T ≥ TC  

( 8)

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θ =

− ( T − TC ) , for T r 1 − TC

In the inset of fig. 8 we have plotted the normalised magnetic entropy change vs rescaled temperature curve. From the inset of fig. 8 it is clear that all the curves merge into a single universal curve. This indicates that the phase transition in the sample is second order

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magnetic phase transition. 4. Conclusions:

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In conclusion, the obtained value of the Landau coefficients form the fitting of the magnetization data with equation of state and in addition the positive slopes of the Arrot plots indicate the 2ndorder magnetic phase transition in the CSMO sample. Sm doping in the pristine CaMnO3 sample destroys the long range antiferromagnetic ordering and ferromagnetism is induced. Simultaneously, the non saturating nature of magnetization within the applied magnetic field range and the smaller value of θCW than TC indicate that there exist

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some amount of AFM phase in the sample. The excellent fit of the M vs. t plot with the stressed exponential indicates the glassy behavior of the sample. The analysis of the magnetization data in the Griffiths phase region using Galitski et al.’s formula indicates that the FM clusters grow in size with increasing magnetic field strength though the susceptibility

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study depicts that the Griffiths phase is suppressed at higher magnetic field. This suppression may be attributed to the increased spin alignment outside the magnetic clusters at increased

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magnetic field. The hysteresis in the studied sample near the transition temperature is not significant and it shows moderate magnetic entropy change at moderate value of magnetic fields near the transition temperature TC. The phenomenological universal curve also confirms the 2nd order nature of phase transition.

Acknowledgement: This work was partially supported by UGC-DAE CSR Indore and DST-FIST Project No. SR/FST/PSI-175/2012 Govt. of India.

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RSC Adv., 2015, 5, 64557.

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Table 1. Crystal data of Rietveld refinement obtained from room temperature XRD pattern.

Orthorhombic, Pnma

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Crystal system, space group Unit cell dimensions (Å)

a = 5.2891, b = 7.4768, c = 5.3034

Volume (Å3)

SC

209.7258 20◦- 80◦

range 2ϴ of data collections

M AN U

RW (%) RB (%)

GOF Atom

O (1) O (2)

AC C

Mn

5.838

7.865

1.023

x

y

z

0.0311

0.25

-0.0036

0.0

0.0

0.5

-0.0057

0.25

0.4324

0.7210

-0.0340

0.2864

EP

Ca/Sm

TE D

Rexp (%)

7.963

13

ACCEPTED MANUSCRIPT Figure captions: Fig. 1: Room temperature X-ray diffraction pattern of CSMO sample. Fig. 2: Temperature dependence of magnetization in FC mode of CSMO. The inset shows the dM/dT as a function of temperature at different magnetic fields.

RI PT

Fig. 3:Magnetic field dependence of magnetization of CSMO at different temperatures. The upper inset shows the Arrot plots at different temperatures and the lower inset shows the enlarged view of the M vs H plot at T = 10K.

Fig. 4: Fitting of the experimental magnetization data with equation (1). The inset shows the

SC

temperature dependence of Landau parameters a(T) and b(T).

Fig. 5: (a) The MTRM vs. t plot fitted with stressed exponential given by equation (2). The

M AN U

inset shows the bifurcation of temperature dependent ZFC and FC magnetization curves at H = 1 kOe. (b) Profile of the magnetization decay of the CSMO sample. The inset shows the fitting of the decay of relaxation rate W (t) with equation (3).

Fig. 6: Variation of inverse magnetic susceptibility with temperature at applied magnetic field of 1 and 8 kOe. The straight line indicates best fit of Curie-Weiss law.

of equation (5).

TE D

Fig. 7: M vs T plot of CSMO in the applied field of 1 and 8 kOe. The solid line is the best fit

Fig. 8: Temperature dependence of ∆SM at different applied magnetic fields calculated from

EP

numerical integration of Maxwell relation. The inset shows the plot of normalized entropy

AC C

change ∆SM (T, H)/∆SMMax versus rescaled temperature θ at different applied magnetic fields.

14

ACCEPTED MANUSCRIPT

Ca0.85Sm0.15MnO3

Yobs

RI PT

Intensity (arb. units)

Ycal

20

30

40

M AN U

SC

Yobs-Ycal

50

2θ (degree)

AC C

EP

TE D

Fig. 1

15

60

70

80

ACCEPTED MANUSCRIPT

-0.4 -0.6

TC = 115K

-0.8 50

10

100

T(K)

0 0

50

200

250

300

SC

H = 1 kOe H = 2 kOe H = 4 kOe H = 6 kOe H = 8 kOe H = 10 kOe

5

150

100

M AN U

M (emu/g)

15

H=1 kOe H=2 kOe H=4 kOe H=6 kOe H=8 kOe H=10 kOe

-0.2

RI PT

20

0.0

↓

dM / dT (emu/g K)

25

150

200

T(K)

AC C

EP

TE D

Fig. 2

16

250

300

350

ACCEPTED MANUSCRIPT

200 100 0 0

1000

2000

3000

30

H/M (Oe-g/emu)

0

-40000

HC = 406 Oe

0 -10

SC

-20

100K 104K 108K 112K 116K 120K 124K 128K 132K

10

-30 -2

-30000

-20000

-10000

H (Oe)

EP

TE D

Fig. 3

17

0

T = 10K

-20

M AN U

-10

M (emu/g)

20

AC C

M (emu/g)

10

104K 106K 108K 110K 112K 114K 116K 118K 120K

300

RI PT

20

M2 (emu/g)2

400

-1

10000

0

1

2

H (kOe) 20000

30000

2600

8 4 0

2500

← 100

2000

→ 110

120

130

1500 1000 500 0 -500

T(K) 2500

Experimental point Fit

2400

SC

H/M (Oe-g/emu)

2700

12

RI PT

2800

a(T) (Oe-g/emu)

b(T) (Oe-g3/emu3)

ACCEPTED MANUSCRIPT

2200 0

2

4

M AN U

2300

6

M (emu/g)

AC C

EP

TE D

Fig. 4

18

8

10

12

ACCEPTED MANUSCRIPT

0.70

(a) 16

0.60

12

FC ZFC

RI PT

M (emu/g)

8 4 0

0.55

0.50

0

100

200

2000

4000

300

T (K)

M AN U

Experimental point Fit

0

SC

MTRM (emu/g)

0.65

6000

8000

10000

t(s)

6.10

(b)

TE D

1E-3

W(t)

6.00

1E-4

EP

1E-5

5.95

Experimental point Fit

1E-6

AC C

M (t) (emu/g)

6.05

1

10

4000

6000

5.90

5.85

0

2000

t (s) Fig 5

19

t (s) 100

8000

1000

10000

ACCEPTED MANUSCRIPT

15000

9000

TG = 167K

SC

↓

6000 θCW = 92K

3000

↓

0 0

50

100

M AN U

1/χ (Oe-g/emu)

RI PT

H=1 kOe

12000

150

200

250

300

350

250

300

350

T(K)

15000

TE D

H=8 kOe

6000

EP

9000

TG = 147K

AC C

↓

θCW = 100K

3000

↓

1/χ (Oe-g/emu)

12000

0

0

50

100

150

T(K)

Fig. 6

20

200

ACCEPTED MANUSCRIPT 16 14

H = 1 kOe H= 8 kOe Fit

12

RI PT

M (emu/g)

10 8 6

SC

4

0 100

110

120

130

M AN U

2

140

T (K)

AC C

EP

TE D

Fig. 7

21

150

160

170

ACCEPTED MANUSCRIPT

0.7

1 kOe 2 kOe 4 kOe 6 kOe 8 kOe 10 kOe

0.4

0.6 0.4 0.2 0.0 -15 -10 -5

0.3

0

5

10 15 20 25

SC

θ

0.2

0.1

0.0 50

100

M AN U

-∆SM(J.Kg-1.K-1)

0.5

1 kOe 2 kOe 4 kOe 6 kOe 8 kOe 10 kOe

0.8

RI PT

0.6

∆SM / ∆SMMax

1.0

150

TE D

T (K)

AC C

EP

Fig. 8

22

200

250

300

ACCEPTED MANUSCRIPT

Highlights 1. Magnetic and magnetocaloric properties of electron doped manganite

AC C

EP

TE D

M AN U

SC

RI PT

Ca0.85Sm0.15MnO3(CSMO) has been studied 2. The presence of the Griffith phase (GP) was identified 3. Small magnetic relaxation has been observed from time dependent magnetization measurement