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) can induce an order of magnitude enhancement in the low temperature (T) resistivity (ρ) of metallic two-dimensional (2D) holes in a narrow (10 nm) GaAs quantum well. Moreover, we show the first observation of saturating behavior of ρ (B) at high B in GaAs system, which suggests our large positive ρ (B) is due to the spin polarization effect alone. We find that this tenfold increase in ρ (B) even persists deeply into the 2D metallic state with the high B saturating values of ρ lower than 0.1 h e2. The dramatic effect of B we observe on the highly conductive 2D holes (with B=0 conductivity as high as 75 e2 h) sets strong constraint on models for the spin dependent transport in dilute metallic 2D systems.