Magnetic phase diagram of (1–x)CuCr1.5Sb0.5S0.5Se3.5–x CuCr2S0.5Se3.5 solid solutions

Abstract

in studies of the CuCr2S4-CuCr1.5Sb0.5S4 solidsolu� tion series, where the endmembers of the system are the thiochromite CuCr2S4 (ferromagnet with ТС = 367 K) and florencovite, CuCr1.5Sb0.5S4 (antiferro� magnet with TN = 23.8 K). Antimony substitution for chromium in these compounds yields a continuous series of CuCr 2- x Sb x S 4 solid solutions, whose mag� netic properties range from ferromagnetic (x = 0) to antiferromagnetic (x = 0.5), with spin glass as an inter� mediate phase, and which exhibit metallic to semi� conducting behavior of electrical conductivity. By analogy with CuCr 1.5 Sb 0.5 S 4 (5), Aminov et al. (6, 7) synthesized new antiferromagnetic semiconduc� tors with the general formula CuCr1.5Sb0.5S 4- xSex with the aim of creating new spintronic materials based on these solid solutions and containing microregions with an increased degree of ferromagnetic order. Single� phase samples were obtained at х = 0, 0.5, 3.5, and 4, which corresponded to the compounds CuCr1.5Sb0.5S4, CuCr1.5Sb0.5S3.5Se0.5, CuCr1.5Sb0.5S0.5Se3.5, and CuCr 1.5 Sb 0.5 Se 4 . All of the mixed selenide and sul� foselenide chromites containing 0.5 antimony atoms per formula unit were inhomogeneous magnetic mate� rials and transformed on cooling first from their para� magnetic state to spin glass (with a spin freezing tem� perature T f = 37-47 K) and then to an antiferromag� netic state with Neel temperatures TN = 21-30 K. The paramagnetic Curie temperature θp ranged from ⎯104 K at х = 0 to +34.8 K at х = 4. Note that, inde� pendent of the sign and magnitude of θp, all of the CuCr 1.5 Sb 0.5 S 4 - x Se x materials were antiferromagnets at 5 K, as evidenced by the linear magnetic field dependence of their magnetization. Abstract—CuCr1.5 + xSb0.5 - xS0.5Se3.5 (x = 0-0.5) mixed chromium chalcogenide spinels have been synthe� sized for the first time. Their magnetic properties have been studied, their magnetic transformations have been identified, and the magnetic phase diagram of the solid solution system has been mapped out. The CuCr2S0.5Se3.5�based ferromagnetic materials have the largest phase field in the system (0.23 ≤ x < 0.5). With decreasing temperature, the materials undergo a reentrant transition to a spin glass state. In the composition range 0.12 ≤ x ≤ 0.23, the transition to a spin glass state occurs from the paramagnetic region. The antiferro� magnetic materials have the smallest phase field (0 ≤ x ≤ 0.12).