Unexpected Spin–Glass Behavior of the Mixed Sulfide-Selenide Chalcogenides TlCr5S8−ySey (y=1–7) Mediated by the Nonmagnetic Sublattice
✍ Scribed by W. Bensch; B. Sander; R.K. Kremer; W. Kockelmann
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 575 KB
- Volume
- 158
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Spin+glass behavior in the series TlCr 5 S 8؊y Se y is mediated by the nonmagnetic anionic sublattice. The magnetic susceptibilities of compounds with 14y48 follow a Curie+Weiss law in the high temperature region above 300 K. As the Se content increases, the magnitude of the Weiss constant drastically decreases from about ؊ 499(3) K for TlCr 5 S 7 Se to ؊ 180(3) K for TlCr 5 Se 8 . Substitution of S by Se leads to structural alterations and stronger ferromagnetic exchange interactions according to the well-established Goodenough+Kanamori rules. In the lowtemperature region, zero 5eld cooled and 5eld cooled susceptibility curves split below a characteristic freezing temperature T f , which increases with rising Se content from 23 to 46 K for TlCr 5 SeS 7 to TlCr 5 Se 7 S, respectively. Using an Ising spin model, the magnetic frustration and the observed spin+glass behavior can be explained by considering di4erent ferromagnetic and antiferromagnetic exchange paths. Neutron di4raction patterns at 5 K show no long-range magnetic order. Analyses of broad humps of magnetic scattering in the di4raction patterns in terms of real space distribution functions show that the antiferromagnetic exchange becomes weaker at the expense of increasing ferromagnetic correlations between 120 and 5 K. Nonlinear changes of , T f , and the e4ective magnetic moment per Cr(III) across the TlCr 5 S 8؊y Se y series, but linear dependencies of T f and on composition within the two regions 14y44 and 44y47 in the low and high temperature regimes, respectively, indicate that a critical Cr+Cr interatomic distance is reached at y+4.