Unravelling Giant Exchange bias in the single layered Ruddlesden-Popper compound SrLaCo_0.5Mn_0.5O₄: A combined studies of Experimental and Density Functional Theory

Discovering exotic magnetism due to competing magnetic interactions in layered perovskites with 3d hetero-species B-site ions has remained an intriguing topic with many unexplained features. Here we study Exchange bias (EB) phenomena in a single layered Ruddlesden-Popper SrLaCo_0.5Mn_0.5O₄ using state of art measurement such as susceptibility, neutron diffraction and training effect along with density functional calculations. EB as large as ~5.5 kOe is observed in SrLaCo_0.5Mn_0.5O₄ which is the highest ever found in any layered transition metal oxides including Ruddlesden-Popper series. Neutron diffraction measurements and together with dc magnetic measurements suggest formation of short range magnetic domains. By carrying out density functional calculations on several model configurations we propose that EB is originated at the boundary between Mn rich antiferromagnetic and Co rich ferromagnetic domains at the sub-nanoscale. Our analysis infers that presence of competing magnetic interactions is sufficient to induce exchange bias and thereby a wide range of materials exhibiting EB can be engineered.