부산대학교 도서관

The crystal structure, electronic structure, and magnetic behaviors of nonmagnetic Ga ions doped double perovskite La1.5Sr0.5CoMnO6 single phase crystals have been investigated. Different from the traditional magnetic dilution effect of nonmagnetic doping, Ga doping in La1.5Sr0.5CoMnO6 enhances the ferromagnetic (FM) exchange interaction of Co3+-O-Mn3+. Moreover, both conventional and spontaneous exchange bias (EB) effects can be tuned by modulating the Ga doping content, which is accompanied by the variation of the Co3+/4+ and Mn3+/4+ and the effective magnetic moment. The EB field and magnetization can be improved by nonmagnetic Ga3+ doping with content lower than 0.2. The evolution of conventional and spontaneous EB effects in La1.5Sr0.5Co1-xGaxMnO6 can be understood in terms of the unidirectional interface anisotropic coupling between FM/anti-FM, and/or FM/spin glass, which is affected by antisite disorder, spin glass, and the uncompensated coupling between Co and Mn.