Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany and Physikalisches Institut, Karlsruher Institut für Technologie, 76128 Karlsruhe, Germany.
Phys Rev Lett. 2013 Dec 20;111(25):257203. doi: 10.1103/PhysRevLett.111.257203. Epub 2013 Dec 18.
The magnetic exchange in hole-doped ferromagnetic cobaltates is investigated by studying the magnetic and electronic properties of La0.7Sr0.3CoO3 films as a function of epitaxial strain. We found a strong-coupling double exchange mechanism between Co3+ (4t(2g) 2e(g)) and Co4+ (3t(2g) 2e(g)) high-spin states mediated by t(2g) electrons--in contrast to the moderate coupling provided by the e(g) exchange in manganites. The strong sensitivity of the Curie temperature TC to the bulk compression can be explained by the small bandwidth of the t(2g)-derived states. A strain-induced Jahn-Teller effect is likewise observed. The experimental results clarify the magnetic exchange mechanism in the cobaltates.
通过研究 La0.7Sr0.3CoO3 薄膜的磁学和电子特性，我们研究了掺杂空穴的亚铁磁钴酸盐的磁交换作用，该薄膜作为外延应变的函数。我们发现了一种强耦合双交换机制，该机制由 t(2g) 电子介导，涉及 Co3+ (4t(2g) 2e(g)) 和 Co4+ (3t(2g) 2e(g)) 高自旋态——与锰氧化物中 e(g) 交换提供的中等耦合形成对比。居里温度 TC 对体压缩的强烈敏感性可以通过 t(2g) 衍生态的小带宽来解释。同样观察到应变诱导的 Jahn-Teller 效应。实验结果阐明了钴酸盐中的磁交换机制。
