tailieunhanh - Metal-insulator phase diagram for the fully diagonal disordered hubbard-model at half filling

The electronic properties of strongly correlated systems with binary type of disorder are investigated using the coherent potential approximation. For half-filled system, two transitions from a band insulator via a metallic state to a Mott insulator are found with increasing the correlation strength of only one of the constituents. Our phase diagram is consistent with those obtained by the dynamical mean field theory. | Communications in Physics, Vol. 26, No. 2 (2016), pp. 159-164 DOI: METAL-INSULATOR PHASE DIAGRAM FOR THE FULLY DIAGONAL DISORDERED HUBBARD MODEL AT HALF-FILLING HOANG ANH TUAN† AND NGUYEN THI HAI YEN Institute of Physics, VAST, Vietnam † E-mail: hatuan@ Received 12 July 2016 Accepted for publication 28 August 2016 Abstract. The electronic properties of strongly correlated systems with binary type of disorder are investigated using the coherent potential approximation. For half-filled system, two transitions from a band insulator via a metallic state to a Mott insulator are found with increasing the correlation strength of only one of the constituents. Our phase diagram is consistent with those obtained by the dynamical mean field theory. Keywords: metal-insulator transition; phase diagram; disordered Hubbard model. Classification numbers: . I. INTRODUCTION In many materials, both the disorder and the correlation effects are present at the same time. The strong correlation effect between electrons has provided us a lot of interesting phenomena, such as high transition temperature superconductivity, metal-insulator transition (MIT), spincharge-orbital orderings and so on. On the other hand, real materials are always subject to different kinds of disorder, such as vacancies, impurities and non-stoichiometric composition. Therefore, the disorder and the electron correlation effects should be considered together to understand the electronic properties of the system. A generic model to study the common influence of disorder and correlations is the Hubbard model including diagonal disorder. For this model, the MIT at noninteger filling have been found by Byczuk et al. [1, 2]. They have shown that at a particular density, equal to the disorder concentration x (or 1 + x), the interplay between disorder-induced band splitting and correlation-induced Mott transition gives rise to a new type of MIT. Recently, a very .