Spin-polarization-induced tenfold magnetoresistivity of highly metallic two-dimensional holes in a narrow GaAs quantum well

We observe that an in-plane magnetic field (B-parallel to parallel to) can induce an order of magnitude enhancement in the low temperature (T) resistivity (rho) of metallic two-dimensional (2D) holes in a narrow (10 nm) GaAs quantum well. Moreover, we show the first observation of saturating behavior of rho(B-parallel to parallel to) at high B-parallel to parallel to in GaAs system, which suggests our large positive rho(B-parallel to parallel to) is due to the spin polarization effect alone. We find that this tenfold increase in rho(B-parallel to parallel to) even persists deeply into the 2D metallic state with the high B-parallel to parallel to saturating values of rho lower than 0.1 h/e(2). The dramatic effect of B-parallel to parallel to we observe on the highly conductive 2D holes (with B=0 conductivity as high as 75 e(2)/h) sets strong constraint on models for the spin dependent transport in dilute metallic 2D systems.