Quasiparticle Evidence for the Nematic State above T_{c} in Sr_{x}Bi_{2}Se_{3}.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Electronic nematicity, where electronic symmetry is lower than crystal symmetry, is observed in various unconventional superconductors.
• The relationship between nematicity and superconductivity remains a key unsolved problem in physics.
• Topological superconductors are a class of materials with unique electronic properties.

Purpose of the Study:

• To provide bulk quasiparticle evidence of nematicity in the topological superconductor Sr_{x}Bi_{2}Se_{3}.
• To investigate the relationship between electronic nematicity and superconductivity in this material.

Main Methods:

• Angle-resolved specific heat measurements were performed.
• The specific heat was analyzed for symmetry properties.

Main Results:

• A clear twofold symmetry in specific heat was observed, despite the material's threefold symmetric lattice.
• This twofold symmetry was present in the normal state, above the superconducting transition temperature.
• The findings are explained by an angle-dependent Zeeman effect arising from an anisotropic density of states.

Conclusions:

• Bulk evidence of electronic nematicity was found in the topological superconductor Sr_{x}Bi_{2}Se_{3}.
• The results highlight the significant interrelation between nematicity and unconventional superconductivity.
• The study provides new insights into the complex behavior of topological superconductors.