  We report a highly unusual temperature dependence in the magnetoresistance of
a weakly interacting high mobility 2D electron gas (2DEG) under a parallel
magnetic field and when the current is perpendicular to the field. While the
linear temperature dependence below 10 K and the exponential temperature
dependence above 40 K agree with existing theory of electron-phonon scattering,
a field induced resistivity saturation behaviour characterized by an almost
complete suppression of the temperature dependence is observed from
approximately 20 to 40 K, which is in sharp contrast to the phenomenology
observed when the current is parallel to the field. Possible origins of this
intriguing intermediate temperature phenomenon are discussed.
