Multi-band conduction behaviour at the interface of LaAlO3/SrTiO3 heterostructures

We have measured the Hall resistance and magneto-resistance (MR) of LaAlO3/SrTiO3 heterojunctions at magnetic fields up to 30 T in a temperature range T = 4 K to 70 K. For temperature below 7 K and above 50 K the devices display linear Hall resistance, indicating that one type of charge carriers dominate the transport. For temperatures between 10 K and 40 K, the Hall resistance is strongly non-linear, and is accompanied by a large positive MR, which is governed by the component of magnetic field normal to the interface. This behaviour in the intermediate temperature regime can be related to thermally activated high-mobility carriers.