Mott transition

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

Quantum phase transition between orbital-selective Mott states in Hund's metals

Abstract: We report a quantum phase transition between orbital-selective Mott states, with different localized orbitals, in a Hund's metals model. Using the density matrix renormalization group, the phase diagram is constructed varying the electronic density and Hubbard $U$, at robust Hund's coupling. We demonstrate that this transition is preempted by charge fluctuations and the emergence of free spinless fermions, as opposed to the magnetically driven Mott transition. The Luttinger correlation exponent is shown to have a universal value in the strong-coupling phase, whereas it is interaction dependent at intermediate couplings. At weak coupling we find a second transition from a normal metal to the intermediate-coupling phase.

A Mott insulator continuously connected to iron pnictide superconductors

Abstract: Iron-based superconductivity develops near an antiferromagnetic order and out of a bad-metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, resonant inelastic X-ray scattering and neutron scattering to demonstrate that NaFe1-xCuxAs near x≈0.5 exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behaviour persisting above the Neel temperature, indicative of a Mott insulator. On decreasing x from 0.5, the antiferromagnetic-ordered moment continuously decreases, yielding to superconductivity ∼x=0.05. Our discovery of a Mott-insulating state in NaFe1-xCuxAs thus makes it the only known Fe-based material, in which superconductivity can be smoothly connected to the Mott-insulating state, highlighting the important role of electron correlations in the high-Tc superconductivity.

The Mott Transition Field Effect Transistor: A Nanodevice?

Abstract: A field effect transistor device (FET), consisting of a nonlinear Mott Insulator channel material, and a high dielectric-constant gate oxide, is explored as a nanoscale device. Experimental functionality of a large scale prototype (5 μm channel length) has been demonstrated. The underlying physics of the device is analyzed and modeled using a time-dependent Hartree approach. Timing estimates suggest a relatively short switching time.

Spectroscopic Studies on the Metal-Insulator Transition Mechanism in Correlated Materials.

Abstract: The metal-insulator transition (MIT) in correlated materials is a novel phenomenon that accompanies a large change in resistivity, often many orders of magnitude. It is important in its own right but its switching behavior in resistivity can be useful for device applications. From the material physics point of view, the starting point of the research on the MIT should be to understand the microscopic mechanism. Here, an overview of recent efforts to unravel the microscopic mechanisms for various types of MITs in correlated materials is provided. Research has focused on transition metal oxides (TMOs), but transition metal chalcogenides have also been studied. Along the way, a new class of MIT materials is discovered, the so-called relativistic Mott insulators in 5d TMOs. Distortions in the MO6 (M = transition metal) octahedron are found to have a large and peculiar effect on the band structure in an orbital dependent way, possibly paving a way to the orbital selective Mott transition. In the final section, the character of the materials suitable for applications is summarized, followed by a brief discussion of some of the efforts to control MITs in correlated materials, including a dynamical approach using light.

Origins of lasing emission in a resonance-controlled ZnO random laser

Abstract: We investigate the origins of lasing emission in a scatterer-resonance-controlled random laser made of ZnO nanopowder over a wide temperature range (20–300 K). At higher temperatures ( K), the lasing emission appears around exciton recombination energies and the lasing threshold carrier density is comparable to the Mott density, indicating that the resonance-controlled random laser is going toward showing excitonic lasing; at lower temperatures, random lasing is caused by usual electron–hole plasma recombination because of the threshold carrier density being much larger than the Mott density.