Spin-polarization-induced tenfold magnetoresistivity of highly metallic two-dimensional holes in a narrowGaAsquantum 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 (100.3em0exnm) 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 0.10.3em0exh∕e². The dramatic effect of B_ we observe on the highly conductive 2D holes (with $B=0$ conductivity as high as 750.3em0exe²∕h) sets strong constraint on models for the spin dependent transport in dilute metallic 2D systems.