Formula omitted]-antisite disorder driven exchange bias effect and Griffiths-like phase in 25% Sr-doped [formula omitted

Abstract

The unusual magnetic behaviour and multiple magnetic phases in double perovskite systems mainly originate from B-antisite disorder and various exchange couplings. Here we report the detailed exchange bias study in the hole doped Sm1.5Sr0.5CoMnO6 double perovskite system. The existence of structural antisite-disorder (Co-O-Co-O-Mn or Mn-O-Mn-O-Co) in the system is revealed. The ordering of Co2+ and Mn4+ gives rise to two ferromagnetic transitions, Tc1∼133 K and Tc2∼114 K. A Griffiths-like phase at ∼153 K is identified by the dc magnetization data above the ferromagnetic ordering temperature. The isothermal magnetization measurements further probe the exhibition of the conventional exchange bias effect and training effect phenomena in our sample. Maximum field shift ∼3.43 kOe in exchange bias effect is observed owing to the exchange couplings at the interfaces of FM/AFM at low temperature induced by B-antisite-disorder. In the 64–300 K temperature range, this disordered double perovskite exhibits insulating characteristics with a variable range hopping type of conduction mechanism. We also notice a negative magnetoresistance of −2.74% at 64 K and 60 kOe magnetic field.