Spin-valley locking in the normal state of a transition-metal dichalcogenide superconductor.
Spin-valley locking in the normal state of a transition-metal dichalcogenide superconductor.
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DOI：
10.1038/ncomms11711
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发表时间：
2016-05-23
影响因子：
16.6
通讯作者：
King PD
中科院分区：
文献类型：
--
作者：
Bawden L;Cooil SP;Mazzola F;Riley JM;Collins-McIntyre LJ;Sunko V;Hunvik KW;Leandersson M;Polley CM;Balasubramanian T;Kim TK;Hoesch M;Wells JW;Balakrishnan G;Bahramy MS;King PD
过渡金属二卤化物(TMDCs)是研究和控制固体中相互缠绕的电子有序的基准体系，超导电性是从电荷密度波态发展而来的。这些相之间的相互作用被认为在铜酸盐、铁基和重费米子系统的非传统超导电性中起着关键作用，但即使对于更中度关联的TMDDC，它们的性质和起源也被证明是有争议的。在这里，我们用自旋和角度分辨光电子能谱和第一原理理论研究了一个典型的例子2H-NbSe_2。我们发现，其标志性集体相出现的正常态的特征是准粒子的自旋被锁定在它们的谷假自旋上。这是强烈的自旋-轨道相互作用和局域反转对称性破坏的结果，而层间耦合进一步驱动了费米表面自旋织构的丰富的三维动量依赖性。这些发现需要重新研究NbSe_2和相关TMDDC中的电荷有序和超导配对的性质。过渡金属二卤化物中相互缠绕的电子有序的起源一直备受争议。在这里，鲍登等人。报告说，这些相出现的正常状态出人意料地是自旋极化的，自旋锁定在山谷和层的伪自旋上。
Metallic transition-metal dichalcogenides (TMDCs) are benchmark systems for studying and controlling intertwined electronic orders in solids, with superconductivity developing from a charge-density wave state. The interplay between such phases is thought to play a critical role in the unconventional superconductivity of cuprates, Fe-based and heavy-fermion systems, yet even for the more moderately-correlated TMDCs, their nature and origins have proved controversial. Here, we study a prototypical example, 2H-NbSe2, by spin- and angle-resolved photoemission and first-principles theory. We find that the normal state, from which its hallmark collective phases emerge, is characterized by quasiparticles whose spin is locked to their valley pseudospin. This results from a combination of strong spin–orbit interactions and local inversion symmetry breaking, while interlayer coupling further drives a rich three-dimensional momentum dependence of the underlying Fermi-surface spin texture. These findings necessitate a re-investigation of the nature of charge order and superconducting pairing in NbSe2 and related TMDCs. The origin of intertwined electronic orders in transition-metal dichalcogenides has long been debated. Here, Bawden et al. report that the normal state, from which these phases emerge, is unexpectedly spin-polarized, with spins locked to both valley and layer pseudospins.