Theory of surface Andreev bound states and tunneling spectroscopy in three-dimensional chiral superconductors
Theory of surface Andreev bound states and tunneling spectroscopy in three-dimensional chiral superconductors
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DOI：
10.1103/physrevb.95.104511
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发表时间：
2016-10
影响因子：
3.7
通讯作者：
S. Tamura;S. Kobayashi;Lu Bo;Yukio Tanaka
中科院分区：
文献类型：
--
作者：
S. Tamura;S. Kobayashi;Lu Bo;Yukio Tanaka
通过改变手征超导体的表面（界面）取向差角，研究了三维手征超导体的表面Andreev束缚态和准粒子隧穿谱.当一个4 × 4的BdG哈密顿量可化为两个2 × 2的块时，得到了一般对势SABS的能量色散的解析公式.对势为$k_z（k_x + ik_y）^{\nu}$（{\nu} = 1，2）$的三维手征超导体的SABS由于点和线节点的共存而具有复杂的能量色散。我们重点研究了在外加磁场作用下，这种对的隧穿谱，磁场会引起准粒子谱的多普勒频移。与以往已知的非常规超导体中的多普勒效应不同，外加磁场可以使零偏压电导谷转变为零偏压电导峰。我们还研究了UPt$_3$可能的配对对称性的SABS和隧道光谱。为此，我们推广了非常规超导结隧穿电导的标准公式，以处理自旋三重态非幺正配对。磁隧穿光谱，即，在磁场存在下的隧道光谱可以作为确定这种材料的配对对称性的指导。
We study the surface Andreev bound states (SABSs) and quasiparticle tunneling spectroscopy of three-dimensional (3D) chiral superconductor by changing the surface (interface) misorientation angle of chiral superconductors. We obtain analytical formula of the energy dispersion of SABS for general pair potential when an original 4$\times$4 BdG Hamiltonian can be reduced to be two 2$\times$2 blocks. The resulting SABS for 3D chiral superconductors with pair potential given by $k_z(k_x + ik_y)^{\nu}$ $({\nu} = 1, 2)$ has a complicated energy dispersion due to the coexistence of both point and line nodes. We focus on the tunneling spectroscopy of this pairing in the presence of applied magnetic field which induces Doppler shift of quasiparticle spectra. By contrast to previous known Doppler effect in unconventional superconductors, zero bias conductance dip can change into zero bias conductance peak by external magnetic field. We also study SABSs and tunneling spectroscopy for possible pairing symmetries of UPt$_3$ . For this purpose, we extend a standard formula of tunneling conductance of unconventional superconductor junctions in order to treat spin-triplet non-unitary pairings. The magneto tunneling spectroscopy, i.e., tunneling spectroscopy in the presence of magnetic field, can serve as a guide to determine the pairing symmetry of this material.