An approach to achieve layered spintronics material using brownmillerite compound Ca_2.5Sr_0.5GaMn₂O₈

Abstract

Magnetic and magnetotransport properties of the naturally occurring layered compounds Ca_2.5−xLa_xSr_0.5GaMn₂O₈ (x = 0, 0.05, 0.075, and 0.1) have been reported. We have succeeded to introduce ferromagnetic ordering in the pure antiferromagnetic system Ca_2.5Sr_0.5GaMn₂O₈ by varying the ratio between Mn³⁺ and Mn⁴⁺ ions. The experimental results of magnetization, magnetoresistance, and neutron diffraction were interpreted on the basis of an electronic phase separation model, where a formation of ferromagnetic clusters (due to DE interactions) inside the layered antiferromagnetic matrix (due to superexchange interactions) in the La-substituted compounds is proposed. Significantly, the present study shows that the magnetic and electronic properties of the layered system Ca_2.5Sr_0.5GaMn₂O₈ can be tuned/optimized by appropriate chemical substitution to achieve a new spintronic material based on naturally occurring layered system for practical applications.