BOUND MAGNETIC POLARONS IN P-TYPE CU2MN0.9ZN0.1SNS4

Bound magnetic polarons (BMP's) in p-type Cu2Mn0.9Zn0.1SnS4 were inves tigated using magnetization measurements. The magnetization M was stud ied from 2 to 60 K in magnetic fields up to 55 kOe. The data show the characteristic features of BMP's in the collective regime. In addition , the onset of antiferromagnetic order in the ''matrix'' surrounding t he BMP's leads to anomalies in the BMP susceptibility at the Neel temp erature of the matrix T-N = 8 K. Below 15 K the low-field magnetizatio n of the BMP's is quite anisotropic. A detailed analysis of the isothe rmal magnetization curves, based on Wolff's work but with some additio nal assumptions, separates the BMP contributions to M from the contrib ution of the matrix. The analysis gives the spontaneous moment m(s) of a single BMP as a function of temperature T, and the concentration N of BMP's. The value m(s) = 143 Bohr magnetons/BMP at the lowest temper atures is consistent with the expected radius of the hole orbit, of or der 10 Angstrom. The observed T dependence of m(s) is compared with th eoretical calculations based on a model that assumes that the wave fun ction in the absence of the p-d interaction is hydrogenic. The calcula ted decrease of m(s) with increasing T is somewhat slower than that de duced from the experimental data. The BMP concentration N, from an ana lysis of the magnetization data, is about 2x10(19) BMP/cm(3) in all th e samples. This N is consistent with the observed hopping conductivity at low temperatures. High-field magnetization data, up to 300 kOe, sh ow the canted-to-paramagnetic phase transition of the matrix. At 1.4 K the transition is near 225 kOe.