Structural and magnetic properties of chemically disordered perovskite SrTi0.5Mn0.5O3

Accepted Manuscript Structural and magnetic properties of chemically disordered perovskite SrTi0.5Mn0.5O3 Shivani Sharma, K. Singh, R. Rawat, N.P. Lalla PII:

S0925-8388(16)32933-4

DOI:

10.1016/j.jallcom.2016.09.179

Reference:

JALCOM 39013

To appear in:

Journal of Alloys and Compounds

Received Date: 14 June 2016 Revised Date:

10 September 2016

Accepted Date: 18 September 2016

Please cite this article as: S. Sharma, K. Singh, R. Rawat, N.P. Lalla, Structural and magnetic properties of chemically disordered perovskite SrTi0.5Mn0.5O3, Journal of Alloys and Compounds (2016), doi: 10.1016/j.jallcom.2016.09.179. 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 Structural and magnetic properties of chemically disordered perovskite SrTi0.5Mn0.5O3 Shivani Sharma*, K. Singh, R. Rawat and N. P. Lalla UGC-DAE Consortium for Scientific research, Indore-452001

Abstract

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Single phase polycrystalline sample of perovskite SrTi0.5Mn0.5O3 (STMO) has been successfully synthesized via solid state reaction route. Its detailed structural and physical properties have been studied using powder x-ray diffraction (XRD), transmission electron microscopy, magnetization, specific heat, and dielectric measurements. Rietveld analysis of

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the powder XRD data and transmission electron microscopy studies confirm that STMO is a disordered perovskite with Pm-3m space group in which titanium and manganese ions are randomly distributed at the 1b site. The dc magnetization (χdc-vs-T) measurements in the

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temperature range 2-300 K reveal a single anomaly at ~13 K with predominant long range canted antiferromagnetic (AFM) ordering. The frequency invariant maximum at 13 K in the ac susceptibility (χac-vs-T) data discards the spin-glass behavior. Despite the presence of sharp feature in magnetization data, the specific heat data (Cp-vs-T) shows only a broad hump around 13 K, which has been attributed to the magneto-structural ordering giving rise to canted AFM state in chemically disorder STMO. Matching with the magnetic and specific

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heat anomaly, the dielectric permittivity also shows a broad anomaly around 14 K, indicating

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the possible magneto-dielectric coupling in STMO system.

PACS No. 75.10.Jm , 75.10.Nr, 74.62.En, 75.40.-s, 75.85.+t , 68.37.Lp

Contact Person: Shivani Sharma UGC-DAE Consortium for Scientific research, University campus, Khandwa Road, Indore-452001, M.P. India, [email protected] 1

ACCEPTED MANUSCRIPT Introduction Perovskite oxides have always been the epitome for various studies resulting in the discoveries

of

superconducting

high-Tc

cuperates,

colossal

magnetoresistive

and

magnetocaloric manganites along with the magnetoelectric (ME) and magneto-dielectric (MD) materials in recent past1,2,3,4. Modification of the basic cubic perovskite (ABO3)

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structure with space-group Pm-3m may occur either through Glazer-tilt of the BO6 octahedra, resulting in a variety of space-group modifications of the Pm-3m structure5 or independently through the chemical ordering at A or B sites, typically known as ordered double perovskites (ODPs). ODPs are generally expressed as A2BB’O6 and according to Anderson et al.6, B and

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B’ cations occupy different sublattices, namely as rock-salt and layered ones. Studies on ODP oxides with rock-salt type sublattice has further enriched the field by revealing coupled

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magnetic, transport and dielectric properties7,8, which provide an additional degree of freedom to its applicability in multifunctional devices9. In recent past, many such ODPs have been studied in which ‘A’ is either some rare earth or alkaline rare earth while B and B’ are 3d transition metal cations6,10,11,. In ODPs with rock salt type sublattice, the B and B’ cations both independently follow a tetrahedral topology and get stacked in alternate layers along <111> of the 222 ordered cubic lattice. B cation is mostly diamagnetic while the B’ cation

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generally carry net magnetic moment with nearest neighbour antiferromagnetic (NN-AFM) interaction. Since in a tetrahedral topology, B’ cation is at equal distance from the other three B’ cations, the NN-AFM interaction between them gets geometrically frustrated12,13,14, similar to that of the triangular lattice in NiGa2S415. It is worth mentioning here that the ODPs may

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exist with different lattice definitions and symmetries6. Sometimes, the superimposition of Glazer tilt of oxygen octahedra over the chemical ordering of B and B’ cations, may alter the

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lattice to say √2√22 while keeping the tetrahedral topology of B and B’ cations almost intact.

The geometric frustration, combined with other parameters like size of the A-site

cation, the effective tolerance factor and the net quantum spin state (1/2, 1 or 3/2)12,13 is expected to give rise the exotic magnetic ground states such as the spin-glass, spin-liquid and spin-ice16,17. Experimentally a variety of short range12,18 and long range magnetic ground states11,19,20 have been realized in ODPs. Depending on the total spin of the B’ cations, anomalous observations on magnetic properties have been reported. For example, La2NaRuO6 and La2NaOsO6 show similar AFM behavior in magnetic measurements but their 2

ACCEPTED MANUSCRIPT neutron diffraction data shows totally different ordered states19. These observations have been attributed to the magnetic frustration or reduced magnetic moment and more or less have been found equally abundant, irrespective of the crystal structures of ODPs being P21/m12 or Fm-3m21. Besides so many studies on geometrically frustrated magnetic states in ODPs12-15, it is yet not clear that whether such frustrated magnetic states are unique to chemically ordered

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perovskite phases or can be realized even in B-site disordered perovskites too. Further, due to the Dzyaloshinskii-Moriya interaction, such perovskite phases are expected to give rise the finite ME coupling22,23. However, studies of ME properties of chemically disordered and magnetically frustrated perovskites are rather sparse.

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In the present paper, we report our studies on the structural, magnetic, dielectric and specific heat properties of antisite disordered SrTi0.5Mn0.5O3 (STMO) system. Here, some

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striking similarity between the magnetic properties of ODPs and that of the chemically disordered STMO has been found. In literature, STMO has generally been considered as ODP and shown to undergo more than one magnetic transition. The first report on the magnetic properties of STMO shows that it undergoes a single magnetic transition from paramagnetic (PM) to ferrimagnetic state at ~45 K24. Later on, Meher et al.25 and Lamsal et al.26 have shown that STMO undergoes two magnetic transitions at ~14 K (TN) and ~45 K

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(Tc), respectively. Our studies preclude the presence of any other transition except at ~14 K, as recently shown by Qasim et al.27. In the recent literature, the 14 K anomaly has been suspected to be spin-glass25,27 and there is no report on the specific heat (Cp-vs-T) and low temperature structural properties of STMO in the present literature. Here, the specific heat

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(Cp-vs-T) behavior of STMO has been studied to estimate the magnetic entropy change near TN. Keeping in view, the link between magnetic frustration and ME coupling; temperature

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dependent dielectric measurements at different frequencies have also been performed to investigate the possible MD effect in this disordered perovskite. Experimental

Polycrystalline sample of STMO has been prepared via solid state reaction route. The

starting reagents SrCO3, TiO2 and MnO2 were dried at 200 oC for 24 hrs. Stoichiometric amounts of the ingredients were thoroughly mixed by manual grinding, effectively for ~8 hrs using agate mortar pestle. Calcination and sintering were done at 1250 oC and 1400 oC effectively for 24 and 36 hrs, respectively with intermediate grinding. During sintering, the heating and cooling rates were kept 200 oC/hr and 100 oC/hr, respectively. Structural phase purity characterization has been done using powder x-ray diffraction (XRD), using the 3

ACCEPTED MANUSCRIPT Rigaku diffractometer, which is mounted on a rotating anode x-ray generator, operating at 10 kW and producing Cu-Kα radiation. Keeping in view, the possibility of antisite ordering in the prepared STMO, slow scan XRD with scan speed of 0.2°/min was also performed, in search of weak superlattice peaks arising due to antisite ordering. Rietveld refinement of the XRD pattern was carried out. To further confirm the antisite order/disorder of titanium (Ti)

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and manganese (Mn) ions, electron diffraction (ED) studies were also performed at room temperature (RT) and 100 K, using Tecnai G2-20 transmission electron microscope (TEM). The dc magnetization measurements were performed using superconducting quantum interference device (SQUID) magnetometer (Quantum Design) in zero field cooled (ZFC),

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field cooled cooling (FCC) and field cooled warming (FCW) conditions. Measurement of ac magnetic susceptibility as function of temperature (χac-vs-T) was also carried out. Dielectric behavior was studied at different frequencies (1–100 kHz) during warming (0.5 K/min) using

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E4980A LCR meter (Agilent Technologies) in the temperature range of 5-300K. Heat capacity measurements were carried out using homemade semi-adiabatic heat pulse calorimeter28,29. Results and Discussion

Figure 1 shows Rietveld refinement of the RT XRD pattern of STMO, refined by

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using two different structural models: (a) First, as a ODP with Fm-3m and (b) second as a disordered perovskite with Pm-3m space-group. Both the fittings appear equally good. But the (111) superlattice peak at ~20°,which should have definitely been present in the case of ODP phase with Fm3m space-group, is found absent in the XRD data. The absence of (111)

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superlattice reflection, even in the slow scanned XRD data, as shown in the inset of Fig. 1(a) clearly indicates that the as prepared STMO is an antisite disordered perovskite structure with

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Pm-3m space-group. Moreover, keeping in view, the typically low atomic scattering powers for x-rays and also the close by core electron numbers in titanium (22) and manganese (25), to further confirm the antisite order/disorder in the STMO, selected area electron diffraction (SAED) was also carried out at RT. Since the atomic scattering power for electrons is ~104 times larger than that of the x-rays, the presence of even the weakest peak (superlattice spot) can be noticed in SAED pattern. To minimize the lattice vibration (Debye-Waller) effects, so as to enhance the visibility of any possible weakest superlattice reflection, if at all present, SAED was performed at 100 K also. Figures 2(a) and (b) shows the <001> and <-101> zone axis SAED patterns of STMO taken from the same grain. The superlattice spot arising due to antisite ordering could be seen along [111] direction with modulation vector [1/2,1/2,1/2] in a 4

ACCEPTED MANUSCRIPT <-101> zone SAED pattern. The expected position of the superlattice spot has been encircled in Fig. 2(b). Absence of the superlattice reflection at [1/2,1/2,1/2] in the SAED confirms that STMO is a antisite disordered sample. The convergent beam electron diffraction (CBED) pattern of STMO is also presented in Fig. 2(c) which shows a single ring. If there has been any type of chemical ordering, a corresponding HOLZ (high order Laue zone) ring should

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have been present, together with the FOLZ (first order Laue zone) ring. Figure 2(d) shows the electron micrograph of the studied grain. Thus the TEM studies confirm that unlike the previous report26, the STMO crystallizes in a disordered perovskite as considered by Qasim et al.27.

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Figure 3 shows the temperature dependent dc magnetization (χdc-vs-T) behavior of STMO in ZFC, FCC and FCW conditions carried out at 0.01, 1.0 and 5.0 tesla magnetic

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fields. The ZFC and FC χdc-vs-T curves corresponding to 0.01 tesla field, show the bifurcation and a sharp anomaly at ~13 K. The occurrence of ZFC-FC bifurcation in χdc-vs-T usually indicates the presence of weak ferromagnetic correlations in the sample. In the present case, the bifurcation does not get suppressed, even at field of 5 tesla field and the temperature of the anomaly shifts to lower temperature side with increasing field i.e., from 13 K to 9 K to 4 K for the field values of 0.01, 1.0 and 5.0 tesla, respectively. This clearly

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indicates that the 13 K anomaly basically corresponds to the strong canted AFM ordering. Unlike other reports24,25,26, we could not observe any transition at ~45 K. Here, it should be noted that the ordering temperature of Mn3O4 is ~45 K30. A small amount (1-2%) of Mn3O4, precipitated during synthesis, will not be detected in the XRD, while sensitive measurements

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like magnetization using SQUID may still detect it. Hence our result shows the presence of single transition at 13 K, as reported by Qasim et al.27. Thus, the absence of 45 K transition in

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our magnetization data assures the pure quality of our sample and the 13 K transition has been attributed to a strong canted AFM ordering, rather than spin-glass. This will be discussed in detail in the next paragraph. Another interesting feature is the small but clear hysteresis in FCC and FCW below 13 K (see the inset of Fig. 3), which was not reported earlier. This feature is highly reproducible and has been confirmed through repeated measurements. The occurrence of hysteresis in a magnetic transition indicates the magnetostructural coupling. Therefore, the anomaly at ~13 K corresponds to a magneto-structural transition, resulting in a canted AFM phase. To confirm the presence of magneto-structural coupling, low-temperature XRD measurements have been performed across TN, from 300 to 2 K. Figure 4(a) shows the full 5

ACCEPTED MANUSCRIPT scan XRD patterns, recorded at various temperatures down to 2 K. We did not observe any qualitative change in the patterns, indicating that as far as structure of the low-temperature phase is concerned it remains the same. The patterns, taken at different temperatures were successfully Rietveld refined using the same space-group Pm-3m. The refined lattice parameter very clearly shows a sudden change in the monotonously decreasing trend of the

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lattice parameter; see the Fig. 4(b). The lattice parameter starts increasing below ~15 K which indicates an isostructural phase transition. The coincidence of structural and magnetic transitions directly confirms the presence of magneto-structural coupling in STMO.

Applying the Curie-Weiss (C-W) fit to the 0.01 tesla 1/χdc-vs-T data (inset-(i) of Fig.

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5), Weiss constant (θc) was determined to be -581 K. Using the Curie constant, the effective paramagnetic moment (µeff) is determined to be 5.01 µB. The experimentally observed value

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of µeff (5.01) is slightly higher than the spin only value for Mn4+ ions. This indicates that possibly the true paramagnetic region for this system lies beyond 300 K, as observed for ODP La2LiRuO613. The frustration index (f = ǀθc/TNǀ) for STMO is estimated to be ~41.5. The large values of θc and f indicate the presence of large magnetic frustration in the system. Magnetization versus field (M-vs-H) measurements has also been performed at 300 and 2 K. At 300 K, the sample shows paramagnetic behavior (data not shown) and at 2 K, the sample

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shows a narrow hysteresis (inset-(ii) Fig. 5). The hysteresis area is very small and also the magnetization does not saturate even at 7 tesla. A rough estimate of the magnetic moment at 2 K was obtained through the M-H data. It is found to be ~ 0.03 µB/formula unit (f.u.). As inferred from the M-T data, these features of M-H also indicate the presence of strong canted

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AFM interaction below TN (13 K), which results in small moment value. To explore the possibility of spin-glass behavior, temperature dependent ac magnetic

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susceptibility (χac-vs-T) measurements were carried out across the TN. Figure 5 shows the χacvs-T behaviour at different frequencies ranging from 0.3 to 966.5 Hz. A clear absence of frequency dispersion in the data discards the presence of any clusture/spin-glass behavior in STMO, as earlier predicted25,27. The specific heat (Cp-vs-T) data was used to estimate the magnetic entropy change (Smag.) during 13 K transition. Figure 6(a) shows the Cp /T-vs-T data of STMO from 5-50 K. One can clearly notice a broad hump like feature extending from 5 to 20 K. This has been attributed to the magnetic contribution (Cmag.) to Cp arising from the canted AFM ordering. The presence of magnetic anomaly is rather clear in Fig. 6(b), which presents Cmag.-vs-T. The

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ACCEPTED MANUSCRIPT method followed to separate the Cmag., consists of the subtraction of lattice contribution (Clatt.), by fitting the Cp /T-vs-T data from 20 to 40 K with the polynomial equation (1), see the Fig. 6(a): . =  +   +   (1) The magnetic heat capacity Cmag. is separated, following the equation:

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. =  − . (2) The maximum of the broad Cmag.-vs-T anomaly is centred on ~12 K. It matches very well with the transition temperatures of canted AFM ordering in dc and ac magnetic

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measurements, which show rather sharper features.

The magnetic entropy change (Smag.) has been obtained using the equation: .  (3)

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. = 

For many ODPs, the magnetic entropy change has been estimated by using the above polynomial fitting and the results are very well in agreement with the theoretical predictions31,32. The value of Smag. estimated using equation (3) over Cmag./T data of Fig. 6(b), is found to be 0.5 J/mole-K. Theoretically, Smag. = R.ln(2S+1), where R is the gas constant

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and S is the total spin. For STMO, with magnetic cation Mn4+ and total spin S = 3/2, the Smag. is theoretically calculated to be 11.5 J/mole-K. Thus the experimentally estimated Smag. change across the canted AFM ordering at ~13 K, is found much smaller than the

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theoretically expected value. There may be two possibilities behind this discrepancy. Firstly, that only a very small fraction of the moments are involved in the AFM ordering as observed in the case of La2NaOsO619 and rest of the moments are still random. Secondly, apart from

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the long-ranged ordered AFM spin state below 13 K, rest of the moments are short range ordered, whose correlations sets in at much higher temperature than TN13. In fact, the inset-(i) of Fig. 5 does indicate this. It can be seen that the magnetic susceptibility deviates from its CW behaviour below 160 K itself. In such situation, the magnetic contribution in Cp will be present well above TN =13 K. Even from the value of µeff., it appears that the true paramagnetic region for this system exist beyond 300 K in the presence of short range correlations at higher temperatures. The same kind of behavior has also been observed for La2LiRuO613.

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ACCEPTED MANUSCRIPT The first possibility (of suppressed moments) has been explored for La2NaOsO619. In this case, the competing NN-AFM interaction between the magnetic cations, following the tetrahedral topology causes the geometric magnetic frustration, resulting in the suppression of magnetic moment and hence only the weak response reflects in the specific heat at low temperatures. In such ODPs, while the magnetic behavior shows striking similarity, the

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specific heat and neutron diffraction data may differ drastically12,19. For example, La2NaOsO6 and La2NaRuO6 both shows long range AFM ground state but La2NaOsO6 doesn’t show magnetic ordering peak in neutron data due to the suppressed moment of magnetic cation, whereas La2NaRuO6 shows clear magnetic ordering peak in specific heat as well as in

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neutron data both. Thus, the occurrence of above discrepancy in the present case although appears to indicate similar magnetic ground state (long range magnetic order of suppressed moments) even in STMO but being a clear case of chemically disordered perovskite, STMO

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does not fit into this category. Competing NN-AFM interaction between the magnetic cations, following the tetrahedral topology is not possible in B-site disordered STMO. To explore the other possibility i.e., the possibility of the existence of short-range spin correlations much above TN as found in La2LiRuO6 and Ba2YRuO613, we tried the best fit to the heat capacity data in the temperature range of 5-50 K with Debye model, which

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gives Debye temperature (θD) to be 415 K. Although, the fit in 5-50 K range appears to be good (similar to the one shown in Fig. 6(a) for the polynomial fit to lattice contribution), but above 50 K, it overshoots the experimental value which is unphysical. The best physical fit to the measured CP data gives Debye temperature of 545 K. The lattice contribution thus

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generated is shown in the inset of Fig. 6(a). Following this, the magnetic entropy is determined to be 10.86 J/mole-K, which is ~80% of the net expected value. This analysis

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suggests that transition is very broad in this system which is quite expected for a highly disordered magnetic system. The absence of clear signature of the transition in heat capacity has been a common occurrence in ceramic oxides33,34. For example in Gd2Pb2O7, magnetic contribution can be seen up to 10 K which is one order of magnitude higher than its magnetic ordering temperature (~1 K)34. In the light of this analysis, it appears that magnetic ordering in STMO sets up at much higher temperature in the form of short range correlations and at ~13 K, it transforms to a long range ordered state. The presence of short range correlation is probably due to the chemically disorder nature of STMO. Not many such observations have been made in disordered perovskites. Therefore, keeping in view, the absence of spin-glass behavior and the occurrence of first order AFM 8

ACCEPTED MANUSCRIPT transition, in chemically disordered perovskite STMO, in which nearest neighbour tetrahedral topology of single magnetic ion is not possible, the appearance of magnetic frustration is unconventional. Due to complete chemical disorder nature of STMO, the nearest neighbour magnetic interaction in STMO should be all inequivalent. Thus, our observations very clearly indicate that unlike ordered double perovskites, B-site disorder perovskites can also lead to a

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frustrated long range ordered magnetic ground state, following a short range spin correlations at higher temperatures. Recently, Chowki et al.35 have also indicated that disorder coupled magnetic frustration is one of the key element which play important role in suppressing the long-range magnetic order. However, it can never be completely neglected, that even in a

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chemically disordered system, some randomly localized tetrahedral topology of nearest neighbour anti-ferromagnetically interacting magnetic cations do exist.

Figure 7 presents the temperature variation of dielectric permittivity at different

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frequencies ranging from 10 kHz to 100 kHz. Meher et al.36 has shown that STMO shows colossal dielectric constant at higher temperature due to Maxwell-Wagner effect. Our main emphasis was to explore the low temperature dielectric properties of the pure STMO down to 2 K to see the effect of magnetic interaction on the dielectric properties as STMO. STMO is an insulating antiferromagnet at low temperatures and one can expect an anomaly at the

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magnetic transition temperature in the dielectric constant. Temperature dependent dielectric permittivity shows a clear broad peak around 13 K extending over a broad temperature range. The broadness in the transition may be due to magnetic frustration in the system arising due to the chemical disorder nature of the sample. There is continuous increase in permittivity

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above 30 K. Therefore, the presence of 13 K anomaly both in the magnetic and dielectric data indicates the occurrence of magnetodielectric (MD) coupling in the STMO system.

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Conclusion

In summary, the structural, magnetic, specific heat and dielectric properties of pure

STMO have been studied. STMO crystallizes in cubic Pm-3m structure, having random distribution of Ti and Mn at 1b site. STMO shows a first order long range canted AFM transition at ~13 K and ac magnetic measurements discard the possibility of spin-glass interactions below 13 K. A small hysteresis in FCC and FCW curve of χdc-vs-T data, below 13 K is associated with magneto-structural transition, as confirmed through low temperature XRD measurements. The analysis of specific heat data of STMO, exhibiting a broad cusp around 13 K, appears to suggest the possibility of moment suppression of manganese ions, like in geometrically frustrated ODPs but the deviation of susceptibility data from C-W law 9

ACCEPTED MANUSCRIPT below 140 K and the Debye fit of the specific heat data suggest that some short range magnetic ordering is taking place in broad temperature range. Here, we have shown that even a chemically disordered perovskite phase can show a frustrated magnetic behavior. The presence of 13 K anomaly in dielectric, magnetization and specific heat data may be related to the presence of possible MD coupling in disordered perovskite. However, detailed

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magnetodielectric measurements are yet to be performed. Acknowledgement

The authors would like to acknowledge Prof. E. V. Sampathkumaran and Dr. Tathamay Basu, TIFR Mumbai for dielectric measurements and Dr. A. Banerjee for

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discussion on magnetic data and Mr. Kranti Kumar for magnetization measurements.

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ACCEPTED MANUSCRIPT Figure captions: Fig. 1 Rietveld refined RT XRD pattern of STMO using (a) Fm-3m and (b) Pm-3m space groups. The inset in Fig. 1(a) shows the slow scan XRD profile around 20°, confirming the absence of (111) peak. The lattice parameters are indicated in the respective figures.

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Fig. 2 (a) <001> and (b) <-101> zone SAED patterns of STMO recorded at 300 K. (c) The CBED pattern and (d) electron micrograph of the studied grain.

Fig. 3 ZFC, FCC and FCW M-T curves of STMO at 0.01, 1.0 and 5.0 Tesla fields. The inset

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exhibits the occurrence of a small hysteresis in FCC and FCW curves at 0.01 Tesla. Fig. 4 Temperature dependent (a) XRD patterns and (b) lattice parameter obtained using Rietveld refinement of XRD data shown in (a). The inset shows the zoomed views of

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changeover point of temperature dependence of lattice parameter. The changeover point (below 15 K) corresponds to the AFM transition in STMO. Fig. 5 Temperature dependent ac-susceptibility at different frequencies from 0.3 to 966 Hz. The insets show (i) Curie-Weiss plot and (ii) M-H hysteresis at 2K. Fig. 6 (a) Cp/T versus T plot and the fitted data using the polynomial (1). The inset shows the

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Debye fit of the same data (Cp-vs-T) for θD = 545K and (b) Variation of the extracted Cmag../T and Smag with respect to temperature. Fig. 7 Temperature dependence of dielectric permittivity (ε') at four different frequencies (10,

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30, 50 and 100kHz). The data was taken during warming cycle. The inset shows the

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possible magnetodielectric coupling in this sample.

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(111)

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Intensity(a.u)

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(111)

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S G - Fm-3m a = 7.7211(1)Å

S G - Pm-3m a = 3.8566(0)Å

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References:

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ACCEPTED MANUSCRIPT 1. T. Kimura, T. Goto, H. Shintani, K. Ishizaka, T. Arima, and Y. Tokura, Nature 426, 55 (2003). 2. M. P. Singh, K. D. Truong, and P. Fournier, Appl. Phys. Lett. 91, 042504 (2007). 3. X. X. Zhang, J. Tejada, Y. Xin, G. F. Sun, K. W. Wong, and X. Bohigas, Appl. Phys. Lett. 69, 3596 (1996).

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SrTi0.5Mn0.5O3 is a chemical disordered perovskite. A first order long range canted AFM transition occurs at ~13 K. The magnetic transition is accompanied with isostructural changes below13 K. Frustrated magnetic ground state exists in chemically disordered system.

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