Kohtaro (Koh) Yamakawa is currently a 5th year Ph.D. student in the Department of Physics advised by Professor James Analytis. Koh received a B.A. in Physics and Mathematics from Columbia University where he researched quantum phase transitions in Mott Insulators using Muon Spin Rotation Spectroscopy with Professor Yasutomo Uemura.
Koh's doctoral research focuses on crystal growth and electrical transport on magnetic materials, particularly on magnetic topological insulator candidates. The mathematical field of topology appears in condensed matter in the form of unique, exotic effects like the robust electrical resistance plateaus in the quantum hall effect, the braiding of anyons in 2D electron gases, and the emergence of dissipationless surface modes in topological insulators. How these effects manifest in materials with magnetism is largely not understood and may lead to ways of applying these phenomena toward next generation technologies.
As a Kavli ENSI fellow, Koh will work on understanding the low dimensional electronic properties of candidate magnetic topological insulators. Preliminary results show that some of these crystals can be exfoliated down to the two dimensional limit, which opens up the possibility of tuning the carrier density and thereby affecting the magnetism and topology. Alongside the Allen group of UC San Diego, he plans on applying the methods he developed in his Ph.D. to synthesize, fabricate, and characterize next-generation topological magneto-electronics devices and elucidate the role topology has in magnetic materials.