Unconventional exchange bias effect driven by phase separation in basically antiferromagnetic Sm0.1Ca0.6Sr0.3MnO3

Abstract

Magnetic investigations, focused on the uncommon behavior of the exchange bias (EB) effect, have been performed for basically antiferromagnetic (AFM) electron doped manganite Sm0.1Ca0.6Sr0.3MnO3. The studied system in the ground state exhibits a heterogeneous spin configuration consisting of the C-type antiferromagnetic phase with the Néel temperature TN−C≈150K, the G-type AFM phase with the Néel temperature TN−G≈70K, and a FM-like phase with very weak spontaneous magnetic moment. The phase separation, into two different AFM phases and a FM-like phase at the temperatures below TN–G, leads to unusual magnetic properties, such as: narrowing of magnetic hysteresis loops in field cooling process, unconventional EB effect associated with spontaneous magnetization at temperatures below TN–C, strong magnetic field dependence of the negative exchange bias at fields below 100Oe turning into practically field independent one for fields above 0.5kOe, significant shift of EB with temperature with a change of the sign from negative at 10K to positive above 40K. The atypical magnetic properties are discussed and related to two different interfaces appearing between coexisting magnetic phases.