The influence of the concentration of Sb ions onto the local crystal and electronic structures of CuCr2−xSbxS4 (x=0.3, 0.4, 0.5) studied by XANES and EXAFS measurements and LAPW numerical calculations

Spin glass state and its correlations with the magnetic and electrical properties as well as with the defectiveness in the spinels CuCr2X4 (X=S, Se) doped with Sb

“…The dilution of magnetic chromium ions in the octahedral subarray by introducing nonmagnetic ions can very strongly influence the magnetic and electrical properties of these compounds. Such effects have been earlier observed by the authors in the stoichiometric compounds of the spinel family CuCr 2−x Sb x S 4 [3][4][5][6] and the nonstoichiometric spinel compounds 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) [7]. The investigations of both the dc and ac magnetic susceptibility as well as of the temperature and magnetic field dependence of the magnetization showed the appearance of spin glass states in all the compounds mentioned above.…”

“…Assuming that both matrices have no defects, then the couplings between the magnetic moments localized on the chromium ions can be realized via three following types of magnetic interactions: (i) the superexchange (the interaction paths: Cr 3+ -X 2− -Cr 3+ , Cr 3+ -X 2− -X 2− -Cr 3+ , Cr 3+ -X 2− -A 2+ -X 2− -Cr 3+ ); (ii) the Zener double exchange interaction in the Cr 3+ -Cr 4+ ion pairs; and (iii) RKKY interaction caused by the appearance in the matrices of the itinerant electrons coming from the existence in them of a few percent of the Cu 2+ ions [1,2,[10][11][12][13][14]. As the crystal field of the ligands splits Table 5 The magnetic coupling constants J 1 /k B (for the first coordination sphere) and J 2 /k B (for the second coordination sphere) of both the stoichiometric and nonstoichiometric spinel compounds under study (calculated from the experimental data in [3][4][5][6][7] Spinel compounds every 3d energy level of the cations into the triplet t 2g and the doublet e g the different overlaps are possible of the wave functions 3d with the p orbitals of anions. Therefore, the exchange chains are created via the so-called -, -and -bands, the latter making different overlaps mentioned above.…”

Nonlinear magnetic susceptibility and the spin glass state in the new nonstoichiometric spinel compounds Cu1+xCr1.5+ySb0.5+zSe4+t (where −0.02≤x≤0.01, 0.03≤y≤0.35, −0.2≤z≤−0.02, 0.01≤t≤0.08)

“…One has to admit that the antimony ions seem here to be mostly trivalent like in the isomorphous solid solutions with sulphur for which three of us contributed to the determination by the XANES measurements a.o. of the valence of these ions which turned out to be equal to +3.32(1) [7].…”

Synchrotron Methods of the Conduction Band Electronic Structure Analysis

“…XANES studies can deliver information on the spin distribution in selected materials even without application of the magnetic dichroism analysis. An interesting example of the spin up and spin down distribution analysis can be reached for CuCr 2−x Sb x S 4 (x = 0.3, 0.4 and 0.5) [28]. These compounds for x = 0.3 and 0.4 are ferromagnetic p-type metals and for x = 0.5 are antiferromagnetic semiconductors.…”

“…These compounds for x = 0.3 and 0.4 are ferromagnetic p-type metals and for x = 0.5 are antiferromagnetic semiconductors. This evolution of the magnetic properties has been studied by XANES for the S K absorption edges [28]. Figure 16 shows the XANES of the S K absorption edges for CuCr 2−x Sb x S 4 (x = 0.3, 0.4 and 0.5).…”