Y. Qiu

Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi2Se3

The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi2Se3) is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb)-doped Bi2Se3. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi2Se3. DOI:https://doi.org/10.1103/PhysRevX.7.011009 Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Published by the American Physical Society

Evidence of nodes in the order parameter of the superconducting doped topological insulator Nb x Bi 2 Se 3 via penetration depth measurements

The low-temperature variation of the London penetration depth

Robust odd-parity superconductivity in the doped topological insulator NbxBi2Se3

\ensuremath{\lambda}(T)

Multiple Fermi Surfaces in Superconducting Nb-Doped Bi 2 Se 3

in the candidate topological superconductor

Time reversal symmetry breaking superconductivity in topological materials

{\mathrm{Nb}}_{x}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{3} (x=0.25)

Electronic fingerprints of Cr and V dopants in the topological insulator Sb2Te3

is reported for several crystals. The measurements were carried out by means of a tunnel-diode oscillator technique in both field orientations (

Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi[subscript 2]Se[subscript 3]

{H}_{\mathrm{rf}}\ensuremath{\parallel}c

An increase in Tc under hydrostatic pressure in the superconducting doped topological insulator Nb0.25Bi2Se3

and

Andreev Reflection Spectroscopy of Topological Superconductor Candidate Nb

{H}_{\mathrm{rf}}\ensuremath{\parallel}ab

_x

planes). All samples exhibited power-law behavior at low temperatures (