Date/Time
Date(s) - 03/02/2005
3:30 pm - 4:30 pm

Title: Zero resistance states from surface acoustic waves

Speaker: Dr. Malcolm Kennett

Institute: Cambridge University

Location: BSB 108

Description:

Recent experiments on high mobility two dimensional electron gases (2DEGs) have shown that when they are illuminated with intense microwave radiation, they display magnetoresistance oscillations and apparently zero resistance states at low magnetic fields. I discuss the situation in which the exciting field has spatial as well as temporal periodicity, as is the case for surface acoustic waves (SAWs). We have studied the magnetoresistance in a 2DEG due to SAWs theoretically and predict a new class of SAW-induced zero resistance states that reflect geometric commensurability between the SAW wavelength and the cyclotron radius of electrons. These states arise from a quantum contribution to the resistance in addition to zero-resistance states that are analogous to those found with microwaves. This work is part of an ongoing effort to investigate and characterize collective excitations in two dimensional electron systems.