NCTS (South)


DATE2012-08-02

TIME11:00

PLACER313, 3F, NCTS, NCKU

FIELDComputational Materials Research

SPEAKER Prof. Xuan Gao(高翾) - Department of Physics, Case Western Reserve University

TITLECancel:Gate Controlled Spin-Orbit Interaction and 1D Thermoelectric Properties in InAs Nanowires

ABSTRACTInAs nanowire provides an interesting one-dimensional (1D) nanomaterial platform for spintronic and thermoelectric applications, owing to its strong quantum confinement and spin orbit interaction (SOI) effects. Manipulating the SOI and thermoelectric transport in InAs nanowires is thus of great interest for both basic quantum transport and applied nanotechnology research. First, we demonstrate efficient control of Rashba SOI in InAs nanowires where a strong electric field is created at the surface of InAs nanowire by either a doubly gated structure or solid electrolyte surrounding gate. Six-fold tuning of Rashba coefficient and nearly three orders of magnitude tuning of spin relaxation time are achieved within only 1 V of gate bias. Second, we present a study of the thermopower and conductance of InAs nanowires in which a gate was used to sweep the Fermi level through quantized 1D subbands of electrons. At low temperatures (T < c.a. 100K), large oscillations in the thermopower and power factor concomitant with the stepwise conductance increases are observed due to the 1D sub-bands formation. This work experimentally demonstrates the possibility to tailor nanowire’s thermoelectric properties through 1D quantum confinement effect, a long-sought goal in nanostructured thermoelectrics research.