Negative imaginary component of AC magnetic susceptibility, metastable states, and magnetic relaxation in La0.6Sr0.35MnTi0.05O3

Off-stoichiometric (La0.6Sr0.35)(MnTi0.05) MnO3 manganite was studied with in-phase (real, chi') and out-of-phase (imaginary, chi '') components of ac susceptibility measurements. Short- and long-time relaxation effects, manifested by the revealed negative chi '', were observed. The effects are explained at the frame of Landau theory of phase transitions where a coexistence of stable and metastable states is considered. It is supposed that the appearance of negative chi '' is an intrinsic feature of magnetic materials with impurities, defects and vacancies blocking nucleation and growth of new phase.