Antimony valence and the magnetization processes in the spinels (Cu)[CrSb]Se4

Influence of Substitution of the Chromium Ions by the Nonmagnetic Sb and Al Ions on the Magnetization Processes in CuCr2X4(X = S, Se) Spinels

“…The above mentioned measurements revealed the appearance of the spin-glass states in all the compounds under study for which magnetic chromium subarray is diluted by nonmagnetic antimony ions [1][2][3]. Moreover, both the stoichiometric compounds with sulfur anion and the nonstoichiometric ones with the selenium anion magnetize very hard.…”

“…2). Moreover, the magnetization isotherms exhibit the hysteresis phenomena and very large paraprocesses [2].…”

“…For both these compounds the Curie temperatures T C as well as the CurieWeiss temperatures θ CW are of the order of 500 K. On the base of these matrices four spinel families were obtained via substitution in the B-sites of the magnetic chromium ions by the nonmagnetic Sb or Al ions. Three of these families turned out to be stoichiometric: CuCr 2−x Sb x S 4 (x = 0.3, 0.4, 0.5) [1], CuCr 2−x Sb x Se 4 (x = 0.1, 0.2, 0.5, 0.8, 1.0) [2], CuCr 2−x Al x Se 4 (x = 0.1, 0.2, 0.3, 0.4, 0.5) whereas the fourth one, namely: Cu 1+x Cr 1.5+y Sb 0.5+z Se 4+t (where −0.02 ≤ x ≤ 0.01, 0.03 ≤ y ≤ 0.35, −0.2 ≤ z ≤ −0.02, 0.01 ≤ t ≤ 0.08) [3] occurred to be nonstoichiometric. All powder samples mentioned above were obtained by ceramic method.…”

Magnetic Coupling in CuCr2X4(X = S, Se) Spinel Compounds Obtained via Substitution of the Chromium Ions by Nonmagnetic Sb or Al Ions

“…Three of these families turned out to be stoichiometric: [3] occurred to be nonstoichiometric. From the extended magnetic measurements of both the magnetization and the magnetic susceptibility it follows that: i) the spin glass states appear in all the compounds in which magnetic chromium sublattice is diluted by nonmagnetic antimony ions [2][3][4], ii) both the stoichiometric compounds with sulfur anion and the nonstoichiometric ones with the selenium anion magnetize very hard.…”

“…Three of these families turned out to be stoichiometric: [3] occurred to be nonstoichiometric. From the extended magnetic measurements of both the magnetization and the magnetic susceptibility it follows that: i) the spin glass states appear in all the compounds in which magnetic chromium sublattice is diluted by nonmagnetic antimony ions [2][3][4], ii) both the stoichiometric compounds with sulfur anion and the nonstoichiometric ones with the selenium anion magnetize very hard. In spite of the external magnetic field applied up to 14 T the samples belonging to these two spinel families are still far from magnetic saturation, iii) the lack of the magnetic saturation as well as the change of the slope of the rectilinear segments in the magnetization isotherms testify to that in all these samples magnetic spin-flop phase transitions take place, iv) in the stoichiometric antimony compounds with the selenium anions, only the sample containing the antimony concentration x equal to 0.1 reaches the magnetic saturation, v) with the increase of the Sb concentration x in these compounds the magnetization decreases very fast and the magnetization processes become more and more hard.…”