Study of Time-Reversal Symmetry Breaking Effects

Quantum materials provide an expansive field of research, which highlights emerging phenomena that challenge our basic understanding of complex solid-state electronic systems, while at the same time lay the foundation for next-generation technologies. A key component of this study is identifying and controlling the symmetry properties of the materials as these may lead to unconventional superconducting phases, subtle magnetic states or unusual spatial arrangements of electronic charge order. The proposed project will primarily focus on “time-reversal symmetry,” that is, the symmetry of some unique properties of a material system under the reversal of the time direction. As a chosen material-system we will fabricate and characterize a stack of exfoliated layers of superconducting WS2 (tungsten disulfide) and ferromagnetic CrI3. Here the ferromagnet is expected to induce an unconventional pairing state into the superconductor, which we will detect using our home-built Sagnac interferometer. This instrument can sensitively detect changes in the polarization of light reflected from time-reversal symmetry braking states of matter and was previously used to discover such subtle effects in superconductors and magnets. Possibly the most significant outcome of this project will be the unveiling of unique electronic excitations, called Majorana Fermions, which are key to future fault-tolerant quantum computing.