Room-temperature ferromagnetism in Sr_(1-x)Y_xCoO_(3-delta) (0.2 < x < 0.25)

TL;DR

This study demonstrates that Sr$_{1-x}$Y$_x$CoO$_{3- ext{delta}}$ exhibits room-temperature ferromagnetism within a narrow composition range, with the highest transition temperature among perovskite cobalt oxides, linked to specific cation ordering.

Contribution

It reports the discovery of room-temperature ferromagnetism in Sr$_{1-x}$Y$_x$CoO$_{3- ext{delta}}$ with a high Curie temperature, highlighting the role of cation ordering in magnetic properties.

Findings

Ferromagnetism observed at 335 K in a narrow composition range.

Saturation magnetization of 0.25 μ_B/Co at 10 K for x=0.225.

Ferromagnetism attributed to Sr/Y cation ordering.

Abstract

We have measured magnetic susceptibility and resistivity of Sr$_{1-x}$Y$_x$CoO$_{3-\delta}$ ($x=$ 0.1, 0.15, 0.2, 0.215, 0.225, 0.25, 0.3, and 0.4), and have found that Sr$_{1-x}$Y$_x$CoO$_{3-\delta}$ is a room temperature ferromagnet with a Curie temperature of 335 K in a narrow compositional range of 0.2 $\leq x\leq$ 0.25. This is the highest transition temperature among perovskite Co oxides. The saturation magnetization for $x=$ 0.225 is 0.25 $\mu_B$/Co at 10 K, which implies that the observed ferromagnetism is a bulk effect. We attribute this ferromagnetism to a peculiar Sr/Y ordering.