Half-Metallicity and Magnetic Anisotropy in Double-Perovskite GdBaCo2O6 Films Prepared via Topotactic Oxidation
Half-Metallicity and Magnetic Anisotropy in Double-Perovskite GdBaCo2O6 Films Prepared via Topotactic Oxidation
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拓扑氧化制备双钙钛矿 GdBaCo2O6 薄膜的半金属性和磁各向异性
DOI：
10.1021/acs.chemmater.2c03335
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发表时间：
2023
影响因子：
8.6
通讯作者：
Hasegawa Tetsuya
中科院分区：
文献类型：
--
作者：
Katayama Tsukasa;Mo Shishin;Chikamatsu Akira;Kurauchi Yuji;Kumigashira Hiroshi;Hasegawa Tetsuya
双钙钛矿GdBaCo2Ox因其令人着迷的电子和磁特性而成为一种很有前途的材料，例如自旋交叉、电荷和自旋态排序、磁场或光诱导的反铁磁到铁磁相变以及大磁阻（MR）。这些特性可以通过改变氧含量（x）来控制，并且增加氧含量对于稳定铁磁序是有效的。然而，尚未获得化学计量相（x = 6），因为扭曲的配位几何结构更喜欢氧空位。在这项研究中，我们报告了通过 x= 5.5 薄膜的局部定向氧化成功合成了 GdBaCo2O6 外延薄膜。 x= 5.5 相和 6 相之间的转变通过低温氧化还原反应是可逆的。 Thex= 6 薄膜在低于 110 K 的居里温度 (TC) 时表现出铁磁和金属行为，在高于 TC 时表现出半导体行为。由于 Co3.5+ 和 Gd3+ 之间的铁磁相互作用，x= 6 薄膜的自发磁化强度为 4.8 μB/f.u.，是双钙钛矿钴矿体系中最大的。它还表现出沿轴的强磁各向异性 (1.7 × 107erg/cm3) 以及与沿轴的 Gd/Ba 排序相关的各向异性 MR 行为。此外，理论计算预测x=6薄膜的半金属性源于中自旋Co3+和低自旋Co4+之间的双交换相互作用。
Double-perovskite GdBaCo2Oxis a promising material owing to its fascinating electronic and magnetic features, such as spin crossover, charge and spin-state ordering, magnetic-field or photo-induced antiferromagnetic-to-ferromagnetic phase transition, and large magnetoresistance (MR). These properties can be controlled by changing the oxygen content (x), and an increase ofxis effective for stabilizing ferromagnetic order. However, a stoichiometric phase (x= 6) has not yet been obtained because the distorted coordination geometry prefers oxygen vacancies. In this study, we report the successful synthesis of GdBaCo2O6epitaxial films via the topotactic oxidation of a film withx= 5.5. The transformation betweenx= 5.5 and 6 phases was reversible via low-temperature redox reactions. Thex= 6 film exhibited ferromagnetic and metallic behavior below the Curie temperature (TC) of 110 K and semiconducting behavior aboveTC. The spontaneous magnetization of thex= 6 film was 4.8 μB/f.u., which is the largest in the double-perovskite cobaltite system owing to the ferromagnetic interaction between Co3.5+and Gd3+. It also exhibited strong magnetic anisotropy along theaaxis (1.7 × 107erg/cm3) and anisotropic MR behavior associated with the Gd/Ba ordering along thecaxis. Furthermore, theoretical calculations predicted that the half-metallicity of thex= 6 film originates from the double exchange interaction between intermediate-spin Co3+and low-spin Co4+.