Evolution from a ferromagnetic to a spin-glass regime in the spinel-type Cu(Cr{sub 1-x}Ti{sub x}){sub 2}S{sub 4}

Journal Article · Sun Mar 15 04:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.12.008· OSTI ID:21212237

Kariya, Fumihiro; Ebisu, Shuji ^[1]; Nagata, Shoichi ^[1]

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1. Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido 050-8585 (Japan)

Successive changes from ferromagnetic, re-entrant mixed, to spin-glass regime have been manifestly found with increasing Ti-composition x in the quaternary spinel-type Cu(Cr{sub 1-x}Ti{sub x}){sub 2}S{sub 4} system. The Curie temperature T{sub c} decreases steeply with increasing x and this transition becomes ill-defined around x=0.47. Two distinct transitions appear below T{sub c} over the range x=0.40-0.47. Coexistence of the ferromagnetism and spin-glass order would be observed below the Gabay and Toulouse transition (T{sub GT}), owing to freezing of the transverse-spin components without changing of the ferromagnetic order parameter. Finally, at a yet lower temperature de Almeida-Thouless transition (T{sub AT}), the longitudinal-spin component freezes randomly at which an irreversibility arises between zero-field-cooled (ZFC) and field-cooled (FC) magnetizations. Over the range of 0.47{<=}x{<=}0.85, a cusp of the ZFC magnetization is seen at T{sub g} like conventional spin-glass. Specimens with x{>=}0.90 remain paramagnetic down to 2.0 K. A magnetic phase diagram between T versus x has been obtained experimentally. The values of the multicritical point in 100 Oe is detected to be x=0.47 and T=7.40K. The low-field magnetization and the phase diagram are satisfactorily explained by the theory of Gabay and Toulouse on the basis of Heisenberg isotropic vector spin model rather than the Ising spin model. - An enlargement of the magnetic phase diagram for Cu(Cr{sub 1-x}Ti{sub x}){sub 2}S{sub 4} at a constant field of 100 Oe over the range of 0.40{<=}x{<=}0.70. The curves give a guide to the eye: para, paramagnetic; ferro, ferromagnetic; SGI, spin-glass I (GT-phase), and SGII: spin-glass II (AT-phase). Three characteristic temperatures of T{sub c},T{sub GT}, and T{sub AT} merge into 7.40 K at x=0.47 in H=100 Oe. This is a multicritical point.

• OSTI ID: 21212237
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 3 Vol. 182; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHROMIUM COMPOUNDS
COPPER COMPOUNDS
CURIE POINT
FERROMAGNETISM
FREEZING
MAGNETIZATION
ORDER PARAMETERS
PARAMAGNETISM
PHASE DIAGRAMS
SPIN GLASS STATE
SPINELS
SULFIDES
TITANIUM COMPOUNDS