Pseudogap and metal-insulator transitions in doped semiconductors
- Russian Research Centre Kurchatov Institute (Russian Federation)
The electronic spectrum of a doped semiconductor described by the Anderson-Holstein impurity model and its conductivity derived from the Kubo linear response theory are calculated. Two characteristic temperatures depending on the doping level x are found in the phase diagram, T{sub PG} and T{sub {lambda}}(x). The pseudogap that opens in the single-particle spectrum at low doping levels and temperatures closes at the lower one, T{sub PG}. The pseudogap state of an insulator is attributed to spin fluctuations in a doped compound. At the higher characteristic temperature T{sub {lambda}}(x),, spin fluctuations vanish and the doped compound becomes a paramagnetic poor metal. Two distinct metal-insulator crossovers between semiconductor-like and metallic temperature dependence of resistivity are found. An insulator-to-poor-metal transition occurs at T{sup *}(x) {approx} T{sub {lambda}}(x). A poor-metal-to-insulator transition at a lower temperature is attributed to the temperature dependence of density of states in the pseudogap. It is shown that both transitions are observed in La{sub 2-x}Sr{sub x}CUO{sub 4}.
- OSTI ID:
- 21067750
- Journal Information:
- Journal of Experimental and Theoretical Physics, Vol. 102, Issue 1; Other Information: DOI: 10.1134/S1063776106010195; Copyright (c) 2006 Nauka/Interperiodica; Article Copyright (c) 2006 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7761
- Country of Publication:
- United States
- Language:
- English
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