Impact of the Fe Doping on Magnetism in Perovskite Cobaltites

Abstract

We systematically studied the magnetic and transport properties for the polycrystalline samples of Fe-doped perovskite cobaltites: Pr${}_{1-y}$Ca${}_y$Co${}_{1-x}$Fe${}_x$O${}_3$ ($y$=0.3, $x$=0-0.15; $y$=0.45, $x$=0-0.3) and Gd${}_{0.55}$Sr${}_{0.45}$Co${}_{1-x}$Fe${}_x$O${}_3$ ($x$=0-0.3). Fe doping leads to an enhancement of the ferromagnetism in the systems of Pr${}_{1-y}$Ca${}_y$Co${}_{1-x}$Fe${}_x$O${}_3$, while the ferromagnetism is suppressed with further increasing Fe content and spin-glass behavior is observed at high doping level of Fe. In contrast, the ferromagnetism is suppressed in the system Gd${}_{0.55}$Sr${}_{0.45}$Co${}_{1-x}$Fe${}_x$O${}_3$ as long as Fe is doped, and no spin-glass behavior is observed in the sample with Fe doping up to 0.3. The competition between ferromagnetic interactions through Fe${}^{3+}$-O-(LS)Co${}^{4+}$ and antiferromagnetic interactions through Fe${}^{3+}$-O-Fe${}^{3+}$ and Fe${}^{3+}$-O-(IS)Co${}^{3+}$ is considered to be responsible for the behavior observed above. The average radius of the ions on A sites plays the key role in determining what type of interactions Fe doping mainly introduces.

13 pages, 10 figures. To be published in Phys. Rev. B