Magnetoresistance at the 2D MIT: Evidence of Micro-emulsion Phases*

Measurements of the in-plane magnetic field B_sat required to achieve full polarization of the electron spins in the strongly interacting two-dimensional electron system in a silicon MOSFET (Metal-Oxide-Semiconductor-Field-Effect Transistor) reveal the occurrence of a phase transition at a well-defined critical electron density for the metal-insulator transition determined from resistivity measurements. The behavior of B_sat as a function of electron density is consistent with the presence of a mixed, electronic micro-emulsion phase proposed by Spivak and Kivelson [1].

[1] B. Spivak, Phys. Rev. B 67, 125205 (2003); B. Spivak and S. A. Kivelson, PRB 70 155114 (2004); Annals of Phys. 321, 2071-2115 (2006).