Magnetoresistance and electronic structure of the half-metallic ferrimagnet $\mathrm{Bi}{\mathrm{Cu}}_{3}{\mathrm{Mn}}_{4}{\mathrm{O}}_{12}$

Magnetoresistance and electronic structure of the half-metallic ferrimagnet $Bi {Cu}_{3} {Mn}_{4} O_{12}$

Kazuhide Takata, Ikuya Yamada, Masaki Azuma, Mikio Takano, and Yuichi Shimakawa

Phys. Rev. B 76, 024429 – Published 23 July 2007

Abstract

A cubic ordered perovskite $Bi {Cu}_{3} {Mn}_{4} O_{12}$ has been synthesized under $6 GPa$ and $1000 ° C$ . $Bi {Cu}_{3} {Mn}_{4} O_{12}$ is a ferrimagnet with $T_{C} = 350 K$ and its saturated magnetic moment is $10.5 μ_{B} ∕ f.u.$ The material showed low-resistive metallic behavior and magnetoresistance (MR) below $T_{C}$ . Its MR was observed over a wide temperature range, and the low-field MR reached $- 28 %$ at $5 K$ . An electronic structure calculation revealed that it had a half-metallic nature and that the large MR observed under a low magnetic field was attributed to a spin-polarized tunneling or spin-dependent scattering effect at grain boundaries.