Identify the Nematic Superconductivity of Topological Superconductor Pd$$_x$$Bi$$_2$$Te$$_3$$ 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 $$_x$$ Bi2Te3 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.