An antiferro-to-ferromagnetic transition in EuTiO3-xHx induced by hydride substitution

Year: 2015 DOI: 10.1021/ic502486e

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Takafumi Yamamoto, Ryuta Yoshii, Guillaume Bouilly, Yoji Kobayashi, Koji Fujita, Yoshiro Kususe, Yoshitaka Matsushita, Katsuhisa Tanaka, Hiroshi Kageyama.   Inorganic Chemistry, 2015, 54, 1501-1507.


We have prepared the oxyhydride perovskite EuTiO3-xHx (x ≤ 0.3) by a low temperature CaH2 reduction of pyrochlore Eu2Ti2O7 and perovskite EuTiO3. The reduced EuTiO3-xHx crystallizes in the ideal cubic perovskite (Pm3̅m), where O/H anions are randomly distributed. As a result of electron doping by the aliovalent anion exchange, the resistivity of EuTiO3-xHx shows metallic temperature dependence. Moreover, an antiferromagnetic-to-ferromagnetic transition is observed even when a small amount of hydride (x ∼ 0.07) is introduced. The Curie temperature TC of 12 K is higher than those of any other EuTiO3-derived ferromagnets. The ferromagnetism can be explained by the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the Eu(2+) spins mediated by the itinerant Ti 3d electrons. The present study shows that controlling the oxide/hydride ratio is a versatile method to tune magnetic and transport properties.