Observation of hysteretic magnetoresistance in Mn-doped GaN nanowires with the mesoscopic Co and Ti∕Au contacts

We have studied the spin dependent tunneling properties of Mn-doped GaN nanowires with ferromagnetic Co contacts. The magnetoresistances were measured between two ferromagnetic Co electrodes, or Co and Ti∕Au electrodes through Mn-doped GaN nanowires. The magnetoresistances of nanowire with the Co electrode indicate hysteretic behaviors, which are commonly observed in tunnel magnetoresistance devices. The magnetoresistance ratio increases from −0.6% at 20K to −9.4% at 1.74K. It is believed that the hysteretic magnetoresistances originate from the tunnel magnetoresistance effect between the ferromagnetic phases of nanowire and Co electrode.