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Magnetic phase diagram of the quasi-2D mixed metal phenylphosphonates
Physica B 284}288 (2000) 1499}1500
Magnetic phase diagram of the quasi-2D mixed metal phenylphosphonates G.E. Fanucci , J.T. Culp , B.C. Watson, R. Backov , H. Ohnuki , D.R. Talham , M.W. Meisel * Department of Chemistry and the Center for Ultralow Temperature Research, University of Florida, P. O. Box 117200, Gainesville, FL 32611-7200, USA Department of Physics and the Center for Ultralow Temperature Research, University of Florida, P. O. Box 118440, Gainesville, FL 32611-8440, USA
Abstract The magnetic properties of pure and mixed (0)x)1) metal phenylphosphonates, Mn M (O PC H ) ) H O, V \V where M is Co or Zn, have been investigated. The pure Mn system consists of quasi-two-dimensional Heisenberg spins that experience long-range canted antiferromagnetic order at ¹ +12 K. The Mn M systems form solid solutions , V \V for all values of x, and the corresponding magnetic phase diagrams (¹ versus x) are presented. 2000 Elsevier Science , B.V. All rights reserved. Keywords: 2D antiferromagnetism; Magnetic phase diagram; Metal phenylphosphonates; Mn Co (O PC H ) ) H O V \V
Two-dimensional (2D) magnetic systems have been studied for many years [1}7]. There has been renewed interest in divalent metal phosphonate systems [6}8], which may be incorporated into Langmuir}Blodgett "lms [9,10]. Here, we report a preliminary study of pure and mixed (0)x)1) metal phenylphosphonates, Mn M V \V (O PC H ) ) H O, where M is Co or Zn. The pure Mn system consists of quasi-2D Heisenberg spins, "J""2.6 K, that experience long-range canted antiferromagnetic order at ¹ +12 K [6}8]. For the case of doping the Mn , system with non-magnetic Zn>, we obtain a reduction of ¹ , and this e!ect is expected [1]. When magnetic , Co> is mixed with the Mn system, an interesting mag-
* Correspondence address: Department of Physics and the Center for Ultralow Temperature Research, University of Florida, P.O. Box 118440, Gainesville, FL 32611-8440, USA. E-mail address: [email protected]#.edu (M.W. Meisel) Permanent address: Lab. of Applied Physics, Tokyo University of Mercantile Marine, Tokyo 135-8533, Japan.
netic phase diagram is generated. If we assume the pure Co> material is a quasi-2D Ising system with S" at low temperature, then ¹ "3.9 K and ¹(s )+7 ,
K suggest "J""7}8 K [2]. In this case, the MnCo system may be considered as a random mixture of 2D classical S" Heisenberg and quantum S" Ising spins. The synthesis of the samples was accomplished by standard procedures [8]. The compounds were analyzed by atomic absorption spectroscopy, FT-IR, and powder X-ray di!raction, Fig. 1. The samples are solid solutions for all values of x. Magnetic studies were performed with a commercial SQUID magnetometer or with a TDO circuit [11], Fig. 2. The magnetic phase diagram, Fig. 3, shows a decrease of ¹ with non-magnetic Zn> doping. Although , a mean-"eld result is not surprising when S", our data contrasts with the stronger decrease of ¹ observed , in K MnF doped with Mg> and other doped 2D
Here, we use H"!J s ) s [12]. G H
0921-4526/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 2 7 0 0 - 3
1500
G.E. Fanucci et al. / Physica B 284}288 (2000) 1499}1500
Fig. 1. The (1 1 0), (0 3 0), and (0 1 1) re#ections for: (a) Co(O PC H ) ) H O; (b) Mn Co (O PC H ) ) H O; (c) Mn(O PC H ) ) H O. The presence of one set of hkl re#ections con"rms the homogeneity of the doped sample.
Fig. 3. Magnetic phase diagram of ¹ versus x. The prediction , of mean-"eld theory is given by the dotted line.
ledges support from the Japanese Ministry of Education, Science, Sports, and Culture.
References
Fig. 2. Typical zero-"eld cooled (ZFC) and "eld cooled (FC) data in the vicinity of ¹ . ,
magnets [1,3]. The decrease of ¹ with Co> doping is , slower than expected by mean-"eld theory. This result arises from the Co> spins acting as subtle magnetic perturbations on the Mn spins. The study of the Co-rich region is in progress [12].
Acknowledgements Aspects of this work were supported, in part, by the National Science Foundation. One of us (H.O.) acknow-
[1] L.J. de Jongh, in: L.J. de Jongh (Ed.), Magnetic Properties of Layered Transition Metal Compounds, Kluwer Academic Publishers, Netherlands, 1990, pp. 1}51, and references therein. [2] R. Navarro, in: L.J. de Jongh (Ed.), Magnetic Properties of Layered Transition Metal Compounds, Kluwer Academic Publishers, Netherlands, 1990, pp. 150}190. [3] S.-W. Cheong et al., Phys. Rev. B 44 (1991) 9739. [4] B. Mombelli et al., J. Phys.: Condens. Matter 10 (1998) 5187. [5] R.R.P. Singh et al., J. Appl. Phys. 83 (1998) 7387. [6] S.G. Carling, P. Day, D. Visser, Inorg. Chem. 34 (1995) 3917. J. Phys.: Condens. Matter 7 (1995) L109. [7] J. Le Bideau et al., J. Magn. Magn. Mater. 140}144 (1995) 1719. [8] G.E. Fanucci et al., J. Am. Chem. Soc. 120 (1998) 5469. [9] C.T. Seip et al., J. Am. Chem. Soc. 119 (1997) 7084. [10] G.E. Fanucci et al., J. Solid State Chem. 145 (1999) 443. [11] P.J.C. Signore et al., Phys. Rev. B 52 (1995) 4446. [12] G.E. Fanucci, in preparation.
Magnetic phase diagram of the quasi-2D mixed metal phenylphosphonates G.E. Fanucci , J.T. Culp , B.C. Watson, R. Backov , H. Ohnuki , D.R. Talham , M.W. Meisel * Department of Chemistry and the Center for Ultralow Temperature Research, University of Florida, P. O. Box 117200, Gainesville, FL 32611-7200, USA Department of Physics and the Center for Ultralow Temperature Research, University of Florida, P. O. Box 118440, Gainesville, FL 32611-8440, USA
Abstract The magnetic properties of pure and mixed (0)x)1) metal phenylphosphonates, Mn M (O PC H ) ) H O, V \V where M is Co or Zn, have been investigated. The pure Mn system consists of quasi-two-dimensional Heisenberg spins that experience long-range canted antiferromagnetic order at ¹ +12 K. The Mn M systems form solid solutions , V \V for all values of x, and the corresponding magnetic phase diagrams (¹ versus x) are presented. 2000 Elsevier Science , B.V. All rights reserved. Keywords: 2D antiferromagnetism; Magnetic phase diagram; Metal phenylphosphonates; Mn Co (O PC H ) ) H O V \V
Two-dimensional (2D) magnetic systems have been studied for many years [1}7]. There has been renewed interest in divalent metal phosphonate systems [6}8], which may be incorporated into Langmuir}Blodgett "lms [9,10]. Here, we report a preliminary study of pure and mixed (0)x)1) metal phenylphosphonates, Mn M V \V (O PC H ) ) H O, where M is Co or Zn. The pure Mn system consists of quasi-2D Heisenberg spins, "J""2.6 K, that experience long-range canted antiferromagnetic order at ¹ +12 K [6}8]. For the case of doping the Mn , system with non-magnetic Zn>, we obtain a reduction of ¹ , and this e!ect is expected [1]. When magnetic , Co> is mixed with the Mn system, an interesting mag-
* Correspondence address: Department of Physics and the Center for Ultralow Temperature Research, University of Florida, P.O. Box 118440, Gainesville, FL 32611-8440, USA. E-mail address: [email protected]#.edu (M.W. Meisel) Permanent address: Lab. of Applied Physics, Tokyo University of Mercantile Marine, Tokyo 135-8533, Japan.
netic phase diagram is generated. If we assume the pure Co> material is a quasi-2D Ising system with S" at low temperature, then ¹ "3.9 K and ¹(s )+7 ,
K suggest "J""7}8 K [2]. In this case, the MnCo system may be considered as a random mixture of 2D classical S" Heisenberg and quantum S" Ising spins. The synthesis of the samples was accomplished by standard procedures [8]. The compounds were analyzed by atomic absorption spectroscopy, FT-IR, and powder X-ray di!raction, Fig. 1. The samples are solid solutions for all values of x. Magnetic studies were performed with a commercial SQUID magnetometer or with a TDO circuit [11], Fig. 2. The magnetic phase diagram, Fig. 3, shows a decrease of ¹ with non-magnetic Zn> doping. Although , a mean-"eld result is not surprising when S", our data contrasts with the stronger decrease of ¹ observed , in K MnF doped with Mg> and other doped 2D
Here, we use H"!J s ) s [12]. G H
0921-4526/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 2 7 0 0 - 3
1500
G.E. Fanucci et al. / Physica B 284}288 (2000) 1499}1500
Fig. 1. The (1 1 0), (0 3 0), and (0 1 1) re#ections for: (a) Co(O PC H ) ) H O; (b) Mn Co (O PC H ) ) H O; (c) Mn(O PC H ) ) H O. The presence of one set of hkl re#ections con"rms the homogeneity of the doped sample.
Fig. 3. Magnetic phase diagram of ¹ versus x. The prediction , of mean-"eld theory is given by the dotted line.
ledges support from the Japanese Ministry of Education, Science, Sports, and Culture.
References
Fig. 2. Typical zero-"eld cooled (ZFC) and "eld cooled (FC) data in the vicinity of ¹ . ,
magnets [1,3]. The decrease of ¹ with Co> doping is , slower than expected by mean-"eld theory. This result arises from the Co> spins acting as subtle magnetic perturbations on the Mn spins. The study of the Co-rich region is in progress [12].
Acknowledgements Aspects of this work were supported, in part, by the National Science Foundation. One of us (H.O.) acknow-
[1] L.J. de Jongh, in: L.J. de Jongh (Ed.), Magnetic Properties of Layered Transition Metal Compounds, Kluwer Academic Publishers, Netherlands, 1990, pp. 1}51, and references therein. [2] R. Navarro, in: L.J. de Jongh (Ed.), Magnetic Properties of Layered Transition Metal Compounds, Kluwer Academic Publishers, Netherlands, 1990, pp. 150}190. [3] S.-W. Cheong et al., Phys. Rev. B 44 (1991) 9739. [4] B. Mombelli et al., J. Phys.: Condens. Matter 10 (1998) 5187. [5] R.R.P. Singh et al., J. Appl. Phys. 83 (1998) 7387. [6] S.G. Carling, P. Day, D. Visser, Inorg. Chem. 34 (1995) 3917. J. Phys.: Condens. Matter 7 (1995) L109. [7] J. Le Bideau et al., J. Magn. Magn. Mater. 140}144 (1995) 1719. [8] G.E. Fanucci et al., J. Am. Chem. Soc. 120 (1998) 5469. [9] C.T. Seip et al., J. Am. Chem. Soc. 119 (1997) 7084. [10] G.E. Fanucci et al., J. Solid State Chem. 145 (1999) 443. [11] P.J.C. Signore et al., Phys. Rev. B 52 (1995) 4446. [12] G.E. Fanucci, in preparation.