Halder Anita, Das Shreya, Sanyal Prabuddha, Saha-Dasgupta Tanusri
Department of Condensed Matter Physics and Material Sciences, S.N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake City, Kolkata, 700 106, India.
School of Physics, Trinity College, Dublin, Ireland.
Sci Rep. 2021 Nov 5;11(1):21764. doi: 10.1038/s41598-021-00959-3.
Understanding magnetism in multiple magnetic sublattice system, driven by the interplay of varied nature of magnetic exchanges, is on one hand challenging and on other hand intriguing. Motivated by the recent synthesis of AA[Formula: see text]BB[Formula: see text]O[Formula: see text] double double perovskites with multiple magnetic ions both at A- and B-sites, we investigate the mechanism of magnetic behavior in these interesting class of compounds. We find that the magnetism in such multiple sublattice compounds is governed by the interplay and delicate balance between two distinct mechanisms, (a) kinetic energy-driven multiple sublattice double exchange mechanism and (b) the conventional super-exchange mechanism. The derived spin Hamiltonian based on first-principles calculations is solved by classical Monte Carlo technique which reproduces the observed magnetic properties. Finally, the influence of off-stoichiometry, as in experimental samples, is discussed. Some of these double double perovskite compounds are found to possess large total magnetic moment and also are found to be half-metallic with reasonably high transition temperature, which raises the hope of future applications of these large magnetic moment half-metallic oxides in spintronics and memory devices.
理解由多种磁性交换性质相互作用驱动的多磁性亚晶格系统中的磁性，一方面具有挑战性，另一方面又引人入胜。受近期合成的在A位和B位均含有多种磁性离子的AA[化学式：见原文]BB[化学式：见原文]O[化学式：见原文]双钙钛矿的启发，我们研究了这类有趣化合物中磁行为的机制。我们发现，此类多亚晶格化合物中的磁性由两种不同机制之间的相互作用和微妙平衡所支配：（a）动能驱动的多亚晶格双交换机制和（b）传统的超交换机制。基于第一性原理计算得出的自旋哈密顿量通过经典蒙特卡罗技术求解，该技术再现了观测到的磁性。最后，讨论了如实验样品中化学计量比偏离的影响。发现其中一些双钙钛矿化合物具有较大的总磁矩，并且还被发现是具有相当高转变温度的半金属，这为这些大磁矩半金属氧化物在自旋电子学和存储器件中的未来应用带来了希望。
