Absence of zero-field-cooled exchange bias effect in single crystalline La2-xAxCoMnO6 (A = Ca, Sr) compounds

Abstract

Magnetic properties of A2BB'O6 (A = rare or alkaline earth ions; B,B' = transition metal ions) double perovskites are of great interest due to their potential spintronic applications. Particularly fascinating is the zero field cooled exchange bias (ZEB) effect observed for the hole doped La2-xAxCoMnO6 polycrystalline samples. In this work we synthesize La2CoMnO6, La1.5Ca0.5CoMnO6, and La1.5Sr0.5CoMnO6 single crystals by the floating zone method and study their magnetic behavior. The three materials are ferromagnetic. Surprisingly, we observe no zero or even conventional exchange bias effect for the Ca and Sr doped single crystals, in sharp contrast to polycrystalline samples. This absence indicates that the lack of grain boundaries and spin glass-like behavior, not observed in our samples, might be key ingredients for the spontaneous exchange bias phenomena seen in polycrystalline samples.

7 pages, 5 figures

References in corpus (4)

• Large zero-field cooled exchange-bias in bulk Mn2PtGa
• Local electronic structure and magnetic properties of LaMn0.5Co0.5O3 studied by x-ray absorption and magnetic circular dichroism spectroscopy
• A phenomenological model for the spontaneous exchange bias effect
• Tuning the spontaneous exchange bias effect with Ba to Sr partial substitution in La${}_{1.5}$(Sr${}_{0.5-x}$Ba${}_x$)CoMnO${}_6$