Enhanced e–e interaction in suspended 2DEG evidenced by transverse magnetic focusing

The features of electron–electron (e–e) interaction in a two-dimensional electron gas (2DEG) in GaAs/AlGaAs heterostructures, including the case of structures detached from the substrate in which this interaction is enhanced, are experimentally studied using transverse magnetic focusing over a wide temperature range. The measurements reveal pronounced resonant ballistic magnetoresistance peaks that are suppressed with increasing temperature and satisfy the condition of magnetic focusing. This suppression is caused by e–e scattering, which gets stronger with increasing temperature. Analysis of the temperature suppression of ballistic peaks allowed us to determine the temperature dependence of the e–e scattering length as well as the effective dielectric constants, which are 12 and 8 in the non-suspended and suspended cases, respectively. The significant decrease in effective dielectric constant in the suspended sample clearly indicates the enhancement of e–e interaction as a result of suspension.