Research Interest

My research interest is to understand and explore emergent phenomena such as magnetism, superconductivity and various kinds of Hall effects in low dimensional systems. To study these interesting condensed matter systems, various kinds of probes have been invented and developed. Among them, optical methods find its benefits with regards to non-invasive nature, spatial- and temporal- resolution.

Magneto-optical Kerr effect (MOKE) microscopy is an optical probe which is sensitive to time-reversal symmetry breaking (TRSB). We utilize modified Sagnac interferometer for the magneto-optical study of ferromagnetic and superconducting materials. The unique property of Sagnac interferometer, such as rejection of all the reciprocal effects such as linear birefringence and high sensitivity without any external magnetic field modulation, has enabled discovery of TRSB in many unconventional superconductors.

One aspect of my research is to develop new and sensitive sensing techniques that can reveal interesting many-body phenomena. We recently developed the Sagnac interferometer for time-resolved magneto-optical measurements and the schematic of the setup is shown below. By replacing a continuous wave light source to a pulsed one, we can measure time-dependent Kerr rotation up to a few GHz. We expect to observe interesting phenomena such as vortex dynamics, local AC Josephson effects, and dynamical TRSB order parameters using this technique.