Temperature- and field-dependence of dynamics in electron glasses

We describe several experimental methods to quantify dynamics in electron glasses and illustrate their use in the glassy phase of crystalline indium-oxide films. These methods are applied to study the dependence of dynamics on temperature and on non-Ohmic electric fields at liquid-helium temperatures. It is shown that over a certain range of temperature the dynamics becomes slower with increasing temperature or upon increasing an applied non-Ohmic field, a behavior suggestive of a quantum glass. It is demonstrated that non-Ohmic fields produce qualitatively similar results as raising the system temperature. Quantitatively, however, their effect may differ markedly. The experimental advantages of using fields to mimic higher temperature are pointed out and illustrated.