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The discovery [1] of the metallic state and metal-to-insulator transition in two-dimensional electron systems challenged the veracity of one of the most influential conjectures in the modern condensed matter physics, which states that [2] "in two dimensions, there is no true metallic behavior". Recently, a two-parameter scaling theory comprehensively describing the metal-to-insulator transition in two dimensions was developed by Punnoose and Finkelstein [3]. I will report experimental verification of the basis of this theory. In particular, we have demonstrated, for the first time, that strong electron-electron interactions stabilize the ´forbiddenĦ metallic state in two dimensions. We have also found that as a result of the interplay between the interactions and disorder, both the resistance and the effective interactions become temperature dependent. We have constructed a resistance-interaction flow diagram of the metal-insulator transition that clearly reveals a quantum critical point, as predicted in Ref.[3]. The metallic side of this diagram is accurately described by the theory without any fitting parameters. On the opposite side of the transition, the disorder prevails and the interactions ´dieĦ in the low-temperature limit giving rise to the insulating state.
[1] S.V. Kravchenko et al., Phys. Rev. B 50, 8039 (1994). [2] E. Abrahams, P.W. Anderson, D.C. Licciardello and T.V. Ramakrishnan, Phys. Rev. Lett. 42, 673 (1979). [3] A. Punnoose and A.M. Finkelstein, Science 310, 289 (2005). |
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