Mott transition

About: Mott transition is a research topic. Over the lifetime, 2444 publications have been published within this topic receiving 78401 citations.

The Anderson-Mott transition

Abstract: The interacting disordered electron problem is reviewed with emphasis on the quantum phase transitions that occur in a model system and on the field-theoretic methods used to describe them. An elementary discussion of conservation laws and diffusive dynamics is followed by a detailed derivation of the extended nonlinear sigma model, which serves as an effective field theory for the problem. A general scaling theory of metal-insulator and related transitions is developed, and explicit renormalization-group calculations for the various universality classes are reviewed and compared with experimental results. A discussion of pertinent physical ideas and phenomenological approaches to the metal-insulator transition not contained in the sigma-model approach is given, and phase-transition aspects of related problems, like disordered superconductors and the quantum Hall effect, are discussed. The review concludes with a list of open problems.

Strong Correlations from Hund’s Coupling

Abstract: Strong electronic correlations are often associated with the proximity of a Mott-insulating state. In recent years however, it has become increasingly clear that the Hund’s rule coupling (intra-atomic exchange) is responsible for strong correlations in multiorbital metallic materials that are not close to a Mott insulator. Hund’s coupling has two effects: It influences the energetics of the Mott gap and strongly suppresses the coherence scale for the formation of a Fermi liquid. A global picture has emerged recently, which emphasizes the importance of the average occupancy of the shell as a control parameter. The most dramatic effects occur away from half-filling or single occupancy. We review the theoretical understanding and physical properties of these Hund’s metals, together with the relevance of this concept to transition-metal oxides (TMOs) of the 3d, and especially 4d, series (such as ruthenates), as well as to the iron-based superconductors (iron pnictides and chalcogenides).

Strain engineering and one-dimensional organization of metal–insulator domains in single-crystal vanadium dioxide beams

Abstract: Correlated electron materials can undergo a variety of phase transitions, including superconductivity, the metal-insulator transition and colossal magnetoresistance. Moreover, multiple physical phases or domains with dimensions of nanometres to micrometres can coexist in these materials at temperatures where a pure phase is expected. Making use of the properties of correlated electron materials in device applications will require the ability to control domain structures and phase transitions in these materials. Lattice strain has been shown to cause the coexistence of metallic and insulating phases in the Mott insulator VO(2). Here, we show that we can nucleate and manipulate ordered arrays of metallic and insulating domains along single-crystal beams of VO(2) by continuously tuning the strain over a wide range of values. The Mott transition between a low-temperature insulating phase and a high-temperature metallic phase usually occurs at 341 K in VO(2), but the active control of strain allows us to reduce this transition temperature to room temperature. In addition to device applications, the ability to control the phase structure of VO(2) with strain could lead to a deeper understanding of the correlated electron materials in general.

Electrical switching and Mott transition in VO2

Abstract: In this paper the problem of the Mott metal-insulator transition in vanadium dioxide driven by an external electric field is considered. Delay time (td) measurements have shown that the experimental value of td is almost three orders of magnitude lower than the theoretical value, calculated in a simple electrothermal model. This suggests that under non-equilibrium conditions (in high electric fields) electron correlation effects contribute to the development of the insulator to metal transition. The extra-carrier injection from Si into VO2 was carried out in the structures Si-SiO2-VO2 on p-type silicon with ρ = 0.1 Ω cm and a SiO2 thickness 70 nm. It has been shown that the metal-insulator transition in VO2 can be initiated by injection, i.e. by the increase of the electron density. The value of the critical density was found to be of the order of the electron density in VO2 in the semiconducting phase, approximately 1018-1019 cm-3. This confirms that the metal-insulator transition in VO2 is the purely electronic Mott-Hubbard transition.

Lecture notes on electron correlation and magnetism

Abstract: Atoms, ions, and molecules crystal field theory Mott transition and Hubbard model Mott insulators Heisenberg magnets itinerant electron magnetism ferromagnetism in Hubbard models the Gutzwiller variational method the correlated metallic state mixed valence and heavy fermions quantum hall effect hydrogen atom single-spin-flip ansatz Gutzwiller approximation Schrieffer-Wolff transformation.