July 29, 2013
A group of researchers including Dr. H. Yuan, Professors R. Arita and Y. Iwasa, from Quantum Phase Electronic Center and Department of Applied Physics, University of Tokyo, in collaboration with Dr. M.S. Bahramy and Professor Nagaosa, the vice-president of CEMS, RIKEN, have succeeded in developing a state-of-the-art field-effect transistor, in which a strong electric field can be applied to WSe2, one of the post-graphene materials.
Their research highlights the possibility to control electrically the spin degrees of freedom, which have been conventionally known to be possible only by the application of an external magnetic field. Layered materials with honeycomb lattice structure usually host peculiar electronic structures.
A typical example is graphene, in which the conducting carriers are massless. Another example is WSe2 which unlike graphene contains heavy elements, and thus inherits strong relativistic spin-orbit effects. Such effects enable us to electrically control not only the orbital degrees of freedom but also the spin degrees of freedom. In particular, interestingly, spins allign in the direction parallel to the electric field, which will provide a new possibility to control the spin degrees of freedom in semiconductors having honeycomb lattice structure.
