2005/01/24 by K. Lai, W. Pan, D. C. Tsui +3
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.72.081313
published as Physical Review B 72, 081313 (R) 2005
arxiv created 2005/01/24 · arxiv updated 2009/12/01
The apparent metal-insulator transition is observed in a high quality two-dimensional electron system (2DES) in the strained Si quantum well of a Si/Si1-xGex heterostructure with mobility μ=1.9 x 105 cm2/Vs at density n=1.45 x 1011 cm-2. The critical density, at which the thermal coefficient of low T resistivity changes sign, is ~ 0.32 x 1011 cm-2, so far the lowest observed in the Si 2D systems. In-plane magnetoresistance study was carried out in the higher density range where the 2DES shows the metallic-like behavior. It is observed that the in-plane magnetoresistance first increases as ~ Bip2 and then saturates to a finite value ρ(Bc) for Bip > Bc. The full spin-polarization field Bc decreases monotonically with n but appears to saturate to a finite value as n approaches zero. Furthermore, ρ(Bc)/ρ(0) ~ 1.8 for all the densities ranging from 0.35 x 1011 to 1.45 x 1011 cm-2 and, when plotted versus Bip/Bc, collapses onto a single curve.