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Two-dimensional metal-insulator transition and in-plane magnetoresistance in a high mobility strained Si quantum well

K. Lai·W. Pan·D. C. Tsui·S. A. Lyon·M. Muhlberger·F. Schaffler
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Abstract

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/Si_{1-x}Ge_x heterostructure with mobility μ=1.9 x 10^5 cm^2/Vs at density n=1.45 x 10^{11} cm^{-2}. The critical density, at which the thermal coefficient of low T resistivity changes sign, is ~ 0.32 x 10^{11} 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 ~ B_{ip}^2 and then saturates to a finite value ρ(B_c) for B_{ip} > B_c. The full spin-polarization field B_c decreases monotonically with n but appears to saturate to a finite value as n approaches zero. Furthermore, ρ(B_c)/ρ(0) ~ 1.8 for all the densities ranging from 0.35 x 10^{11} to 1.45 x 10^{11} cm^{-2} and, when plotted versus B_{ip}/B_c, collapses onto a single curve.

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K. Lai, W. Pan, D. C. Tsui, S. A. Lyon, M. Muhlberger, F. Schaffler. 2005-01-24. Two-dimensional metal-insulator transition and in-plane magnetoresistance in a high mobility strained Si quantum well. https://doi.org/10.1103/physrevb.72.081313

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