四面体超晶格中高温铁磁半导体的预测

Prediction of high-temperature ferromagnetic semiconductors in tetrahedral superlattices

铁磁(FM)半导体兼具半导体(如逻辑器件)和磁性材料(如记忆存储器)的优点,半个多世纪以来一直受到广泛关注.然而,铁磁半导体的发展受到候选材料稀缺以及居里温度低的阻碍.铁磁性通常在具有八面体配位的过渡金属化合物中被发现.而具有较小晶体场分裂和较弱反铁磁(AFM)直接交换的四面体配位化合物可能是高温铁磁体的潜在候选者,但很少被探索.在这项工作中,我们提出了高温铁磁半导体可以在四面体配位超晶格(SL)中实现.在第一性原理计算的基础上,我们系统地研究了一系列MX/TMX (MX表示12-16,13-15或14-14族四面体半导体,TM表示3d过渡金属,X表示配体)超晶格.其中,SiC/CrC SL是一种稳定的铁磁半导体材料,具有0.363 eV的间接带隙和~935 K的高居里温度.此外,我们还探讨了Cr原子层的分布和层间磁耦合,预测了单轴应变引起了反铁磁到铁磁的相变.这些发现为实现四面体配位超晶格的高温铁磁半导体在未来自旋电子应用中开辟了新的机会.

Ferromagnetic(FM)semiconductors combine the advantages of semiconductors(e.g.,logic devices)and magnetic materials(e.g.,memories)and have garnered increasing amounts of attention for more than half a century.However,the development of FM semiconductors faces challenges due to the scarcity of suitable candidates and their low Curie temperature.Traditionally,ferromagnetism is observed in transition metal compounds with octahedral coordination.In contrast,tetrahedral coordination compounds,with smaller crystal field splitting and weaker antiferromagnetic(AFM)direct exchange,hold promise as potential candidates for high-temperature ferromagnets but remain largelyunexplored.In this work,we propose that high-temperature FM semiconductors can be realized in tetrahedral coordination superlattices(SLs).On the basis of first-principles calculations,we systematically investigated a series of MX/TMX(MX denotes group 12-16,13-15 or 14-14 tetrahedral semiconductors,TM denotes a 3d transition metal,X denotes the ligand)SL.Among them,SiC/CrC SL emerges as a stable FM semiconductor with an indirect band gap of 0.363 eV and a high Curie temperature(Tc)of~935 K.Furthermore,the distributions of the Cr atomic layer and interlayer magnetic couplings are explored.A uniaxial-pressure-induced AFMto-FM phase transition is predicted.These discoveries present novel opportunities for realizing high-temperature FM semiconductors in tetrahedral coordination SLs,offering potential advancements in future spintronic applications.