Identify the Nematic Superconductivity of Topological Superconductor Pd_xBi₂Te₃ by Angle-dependent Upper Critical Field Measurement

Odd-parity superconductivity is recognized as a key ingredient to realize topological superconductivity. In Bi2Se3-based bulk topological superconductors, the odd- parity pairing, which spontaneously breaks the threefold rotational symmetry of the crystal, leading to a subsidiary nematic order, was discovered. The nematic superconducting state can be identified by thermodynamic measurement, nuclear magnetic resonance measurement, ac-chi measurement, magnetic torque measurement or magnetoresistance measurement. Here, the single crystal of topological superconductor Pd xBi2Te3 was grown. Its upper critical fields were obtained by magnetoresistance measurement in various magnetic field orientations parallel to the basal plane. The in-plane upper critical fields clearly demonstrate a twofold symmetry that break the threefold crystal symmetry. This provides experimental evidence that Pd-doped Bi2Te3 is a nematic topological superconductor similar to the Cu-, Sr-, and Nb-doped Bi2Se3.