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arXiv · 1608.08164

Evidence of nodes in the order parameter of the superconducting doped topological insulator Nb$_x$Bi$_2$Se$_3$ via penetration depth measurements

M. P. Smylie·H. Claus·U. Welp·W. -K. Kwok·Y. Qiu·Y. S. Hor·A. Snezhko
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Abstract

The low-temperature variation of the London penetration depth $\lambda (T)$ in the candidate topological superconductor Nb$_x$Bi$_2$Se$_3$ (x = 0.25) is reported for several crystals. The measurements were carried out by means of a tunnel-diode oscillator (TDO) technique in both field orientations ($H_{rf} \parallel$ $c$ and $H_{rf} \parallel$ $ab$ planes). All samples exhibited power law behavior at low temperatures ($\Delta\lambda\sim T^2$) clearly indicating the presence of point nodes in the superconducting order parameter. The results presented here are consistent with a nematic odd-parity spin-triplet $E_u$ pairing state in Nb$_x$Bi$_2$Se$_3$.

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M. P. Smylie, H. Claus, U. Welp, W. -K. Kwok, Y. Qiu, Y. S. Hor, A. Snezhko. 2016-08-29. Evidence of nodes in the order parameter of the superconducting doped topological insulator Nb$_x$Bi$_2$Se$_3$ via penetration depth measurements. https://doi.org/10.1103/physrevb.94.180510

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