Linear and nonlinear susceptibilities of samarium manganites

The temperature and field behaviors of the linear and nonlinear responses t o a weak ac magnetic field in the Sm1 - xSrxMnO3 manganites with x = 0.25, 0.3, and 0.4 have been investigated. It is found that the hysteresis of the second harmonic of magnetization in the dc magnetic field arises in the fa r-paramagnetic range at T less than or equal to 180 K, whereas the hysteres es of the linear susceptibility and the dc resistivity are observed at lowe r temperatures. This phenomenon is associated with the formation of macrosc opic ferromagnetic (ferrimagnetic) domains in the paramagnetic matrix. The shape of the temperature dependence of the linear susceptibility at T > T-c is determined by the degree of doping, and the susceptibility itself nonmo notonically depends on x. (C) 2000 MAIK "Nauka/Interperiodica".