Stability of a Nonunitary Triplet Pairing on the Border of Magnetism in UTe$_2$
Stability of a Nonunitary Triplet Pairing on the Border of Magnetism in UTe$_2$
复制标题
UTe$_2$ 磁边界上非酉三重态配对的稳定性
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
A. Nevidomskyy
中科院分区：
文献类型：
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作者：
A. Nevidomskyy
受最近在UTE_2中发现超导电性的启发，我们分析了各种三重态超导序参数的稳定性和节点结构。结合对称群理论、唯象朗道自由能和弱耦合BCS理论，我们证明了即使在没有长程磁序的情况下，手征非酉超导序也可以稳定在UTE$2的铁磁性边界上。我们进一步对所谓的“小”费米面进行了第一性原理密度泛函理论(DFT)计算，发现它与最近的角分辨光电子能谱研究和DFT+DMFT计算很好地符合。这使得我们能够阐明超导带隙的节点结构，我们发现它通常沿着结晶学方向具有点节点，这与实验一致。分析了这些点节点及其相关的Majorana表面态的拓扑稳定性。预测的超导态的非么正结构支持最近的扫描隧道显微镜(STM)数据中观察到的手征边缘模式，并被预测导致非零磁光克尔效应。
Motivated by the recent discovery of superconductivity in UTe$_2$, we analyze the stability and nodal structure of various triplet superconducting order parameters. Using a combination of symmetry group-theoretical analysis, phenomenological Landau free energy and weak-coupling BCS theory, we show that chiral nonunitary superconducting order can be stabilized on the border of ferromagnetism in UTe$_2$, even in the absence of long-range magnetic order. We further perform first principles density functional theory (DFT) calculations of the so-called "small" Fermi surface, excluding the contribution of U $f$-electrons, and find it to be in excellent agreement with the recent angular resolved photoemission study and DFT+DMFT calculations. This permits us to elucidate the nodal structure of the superconducting gap, which we find generically to possess point nodes along the crystallographic $a$ direction, in agreement with experiments. The topological stability of these point nodes and their associated Majorana surface states is analyzed. The nonunitary structure of the predicted superconducting state supports chiral edge modes observed in recent scanning tunneling microscopy (STM) data and is predicted to result in a non-vanishing magneto-optical Kerr effect.