Persistent spin helix in Rashba-Dresselhaus ferroelectric CsBiNb2O7
Persistent spin helix in Rashba-Dresselhaus ferroelectric CsBiNb2O7
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DOI：
10.1103/physrevmaterials.3.084416
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发表时间：
2019-08-19
影响因子：
3.4
通讯作者：
Picozzi, Silvia
中科院分区：
文献类型：
--
作者：
Autieri, Carmine;Barone, Paolo;Picozzi, Silvia
铁电Rashba半导体（FERSC）是一类新型的多功能材料，具有巨大的Rashba自旋分裂，可以通过改变电极化来逆转。虽然它们是自旋场效应晶体管中作为沟道的优秀候选者，但实验研究到目前为止仅限于半导体GeTe，其中铁电开关通常被重掺杂和/或大漏电流阻止。在这里，我们报告，CsBiNb 2 O 7，一个层状钙钛矿的Dion-Jacobson型，是一个强大的铁电体，具有足够强的自旋轨道耦合和自旋织构可逆的电场。此外，我们还发现，由于铁电相的低对称性，其最高价带的自旋织构与动量准无关。动量空间中的特殊自旋极化模式可能会产生所谓的“持续自旋螺旋”，这是一种特殊的自旋波模式，可以保护自旋在扩散输运机制中不受退相干影响，从而可能确保这种材料具有非常长的自旋寿命。
Ferroelectric Rashba semiconductors (FERSC) are a novel class of multifunctional materials showing a giant Rashba spin splitting which can be reversed by switching the electric polarization. Although they are excellent candidates as channels in spin field effect transistors, the experimental research has been limited so far to semiconducting GeTe, in which ferroelectric switching is often prevented by heavy doping and/or large leakage currents. Here, we report that CsBiNb2O7, a layered perovskite of Dion-Jacobson type, is a robust ferroelectric with sufficiently strong spin-orbit coupling and spin texture reversible by electric field. Moreover, we reveal that its topmost valence band's spin texture is quasi-independent from the momentum, as a result of the low symmetry of its ferroelectric phase. The peculiar spin-polarization pattern in the momentum space may yield the so-called "persistent spin helix," a specific spin-wave mode which protects the spin from decoherence in the diffusive transport regime, potentially ensuring a very long spin lifetime in this material.