Parabolic negative magnetoresistance in two-dimensional electron gas in InGaAs/InP

We have measured the magnetoresistance of two-dimensional electron gas in modulation-doped In
_0.53
Ga
_0.47
As/InP heterostructures in the temperature range from 40 mK to 4.2 K. In magnetic fields less than about 1 T and before the onset of Shubnikov-de Haas oscillations a large negative magnetoresistance was observed, which followed a quadratic dependence on the magnetic field. The observed negative magnetoresistance can be explained in terms of electron-electron interaction in two-dimension.