抄録
Realizing an electronic phase competition in a material is a promising approach to induce a large electronic change by a small external field. One of typical materials showing the phase competition is the half-doped perovskite manganite, in which the ground state drastically changes between the antiferromagnetic-insulating (AFM-I) and ferromagnetic-metallic (FM-M) states depending on the slight difference in the band width. Near the phase boundary, the two phases coexist and compete with each other, giving rise to a gigantic field response like the colossal magnetoresistance. We show in this paper the observation of a self-organized anisotropic phase separation with use of a microwave impedance microscope for a thin film of Nd0.5Sr0.5MnO3, which locates on the verge of the phase boundary. We also show an artificially tailored phase separation and its magnetic control realized in superlattices composed of Pr0.5Ca0.5MnO3 (AFM-I) and La0.5Sr0.5MnO3 (FM-M).