Structural evolution and skyrmionic phase diagram of the lacunar spinel GaMo4Se8
Structural evolution and skyrmionic phase diagram of the lacunar spinel GaMo4Se8
复制标题
DOI：
10.1103/physrevmaterials.4.064402
复制
发表时间：
2020-05
期刊：
影响因子：
--
通讯作者：
Emily C. Schueller;D. Kitchaev;J. Zuo;J. D. Bocarsly;Joya A. Cooley;A. Van der Ven;Stephen D. Wilson;R. Seshadri
中科院分区：
文献类型：
--
作者：
Emily C. Schueller;D. Kitchaev;J. Zuo;J. D. Bocarsly;Joya A. Cooley;A. Van der Ven;Stephen D. Wilson;R. Seshadri
在 $AB_4Q_8$ 空心尖晶石中，电子结构是根据四面体 $B_4$ 簇的簇间和簇内相互作用来描述的，调整这些可以导致无数令人着迷的电子和磁性基态。在这项工作中，我们采用磁测量、同步加速器 X 射线和中子散射以及第一原理电子结构计算来研究 GaMo$_4$Se$_8$ 中结构相演化和磁相演化之间的耦合，包括磁相图中斯格明子状态的出现。我们表明，室温立方 $F\overline{4}3m$ 结构的两种不同的 Jahn-Teller 畸变之间的竞争导致基态 $R3m$ 相和亚稳态 $Imm2$ 相共存。计算表明，这两个相的磁性非常不同，$Imm2$ 相表现出单轴铁磁性，$R3m$ 相呈现复杂的磁相图，包括平衡尼尔型斯格明子，从近 $T$ = 28 K 稳定到 $T$ = 2 K（最低测量温度）。微小的结构变形引起的磁性行为的巨大变化表明，GaMo$_4$Se$_8$ 是一种令人兴奋的候选材料，可通过机械手段调节非常规磁性。
In the $AB_4Q_8$ lacunar spinels, the electronic structure is described on the basis of inter- and intra-cluster interactions of tetrahedral $B_4$ clusters, and tuning these can lead to myriad fascinating electronic and magnetic ground states. In this work, we employ magnetic measurements, synchrotron X-ray and neutron scattering, and first-principles electronic structure calculations to examine the coupling between structural and magnetic phase evolution in GaMo$_4$Se$_8$, including the emergence of a skyrmionic regime in the magnetic phase diagram. We show that the competition between two distinct Jahn-Teller distortions of the room temperature cubic $F\overline{4}3m$ structure leads to the coexistence of the ground state $R3m$ phase and a metastable $Imm2$ phase. The magnetic properties of these two phases are computationally shown to be very different, with the $Imm2$ phase exhibiting uniaxial ferromagnetism and the $R3m$ phase hosting a complex magnetic phase diagram including equilibrium Neel--type skyrmions stable from nearly $T$ = 28 K down to $T$ = 2 K, the lowest measured temperature. The large change in magnetic behavior induced by a small structural distortion reveals that GaMo$_4$Se$_8$ is an exciting candidate material for tuning unconventional magnetic properties $via$ mechanical means.