Observation of magnetoresistance polarity reversal in 3D to 2D tunneling in an asymmetric GaMnAs resonant tunneling diode

We investigate the magnetoresistance (MR) characteristics of a GaMnAs-based asymmetric resonant tunneling structure with a 3D GaMnAs top layer and a 2D GaMnAs quantum well (QW). The incorporation of a 2D layer distinguishes our device from the many conventional devices reported in the literature in that the MR characteristics of our device result from 3D to 2D tunneling, whereas MR in a conventional device results from 3D to 3D tunneling. By observing a shift of negative differential resistance (NDR) features as an in-plane magnetic field is varied, we infer that the 3D to 2D tunneling magnetoresistance (TMR) in our device has the opposite sign from conventional TMR in GaMnAs. We relate this difference to the effect of quantum confinement on the 2D density of states in the GaMnAs QW.