Z3-vestigial nematic order due to superconducting fluctuations in the doped topological insulators NbxBi2Se3 and CuxBi2Se3

摘要

Field-angle-resolved magnetoresistance data taken at 350 mK (Sample 1) for various alignments of the magnetic field in the Bi Se basal plane. The additional circles mark the characteristic fields in which the magnetoresistance reaches 75% of the normal state value. The data were shifted vertically by −0.4 mΩ cm for better clarity, except for the  = 98° data. Polar plot of characteristic fields where the magnetoresistance reaches 75% of the normal state value, depending on the field direction in the Bi Se basal plane. Only the full squares are real data, while the open squares are the same data shifted by 180° to better illustrate the full angular dependence. In the center, the corresponding crystal structure is added. The lines are theoretical expectations of a superconductor with trigonal symmetry without (green) and with (orange) vestigial nematic order.