Multiorbital ferroelectric superconductivity in doped SrTiO3
Multiorbital ferroelectric superconductivity in doped SrTiO3
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DOI：
10.1103/physrevb.100.094504
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发表时间：
2019-09-03
影响因子：
3.7
通讯作者：
Yanase, Youichi
中科院分区：
文献类型：
--
作者：
Kanasugi, Shota;Yanase, Youichi
SrTiO 3是一个独特的例子系统，同时表现出量子顺电性和超导性。因此，可以预期超导态与本征铁电不稳定性密切相关。事实上，最近的实验表明，在钙取代SrTiO 3的超导性和铁电性共存相的存在。在本文中，我们提出SrTiO_3可以作为铁电超导电性的平台，其特征在于在超导状态下的铁电转变。通过对t（2g）电子的多轨道模型的分析，我们发现铁电超导电性是通过两种不同的机制稳定的，这两种机制依赖于自旋-轨道耦合的存在.首先，铁电超导状态是稳定的稀载流子密度制度，由于铁电诱导的Lifshitz转变。第二，它在磁场下稳定，与载流子密度无关。阐明了铁电超导的多轨道或多能带性质的重要性。然后，我们预测了一个拓扑Weyl超导态的铁电超导相的SrTiO 3。
SrTiO3 is a unique example of a system which exhibits both quantum paraelectricity and superconductivity. Thus, it is expected that the superconducting state is closely related to the intrinsic ferroelectric instability. Indeed, recent experiments suggest existence of a coexistent phase of superconductivity and ferroelectricity in Ca-substituted SrTiO3. In this paper, we propose that SrTiO3 can be a platform of the ferroelectric superconductivity, which is characterized by a ferroelectric transition in the superconducting state. By analyzing a multiorbital model for t(2g) electrons, we show that the ferroelectric superconductivity is stabilized through two different mechanisms which rely on the presence of the spin-orbit coupling. First, the ferroelectric superconducting state is stabilized in the dilute carrier density regime due to a ferroelectricity-induced Lifshitz transition. Second, it is stabilized under a magnetic field independent of the carrier density. The importance of the multiorbital or multiband nature for the ferroelectric superconductivity is clarified. Then, we predict a topological Weyl superconducting state in the ferroelectric superconducting phase of SrTiO3.