부산대학교 도서관

Magnetic and magnetotransport properties of the naturally occurring layered compounds Ca2.5−xLaxSr0.5GaMn2O8 (x = 0, 0.05, 0.075, and 0.1) have been reported. We have succeeded to introduce ferromagnetic ordering in the pure antiferromagnetic system Ca2.5Sr0.5GaMn2O8 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 Ca2.5Sr0.5GaMn2O8 can be tuned/optimized by appropriate chemical substitution to achieve a new spintronic material based on naturally occurring layered system for practical applications.