Scaling magnetoresistance induced by superconducting contacts in n-type GaAs

A low-temperature (T<4.2 K) transport study of n-type doped (1019 cm-3) bulk GaAs reveals an enhancement of the electrical resistance, R/R10-3, below a critical temperature, Tc=3.4 K, at low magnetic fields, B<30 mT, when superconducting In point contacts are used as the current and voltage probes. The resistance correction is shown to be a homogeneous function of the magnetic field, B, and the reduced temperature, =(Tc-T)/Tc, as [R(T,B)/R]s=Af(B) with =1.00 0.25, and =1.00 0.33, in the vicinity of the critical point. The effect is attributed to proximity superconductivity in GaAs resulting from the use of superconducting point contacts. © 1992 The American Physical Society.