Mott transition

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

Collective excitations photoemission spectra and optical gaps in strongly correlated Fermi systems

Abstract: We analyze the single-particle and collective excitations near the metal to charge-transfer insulator transition, using the slave-boson technique. We show that the Mott transition can be interpreted as a softening of an auxiliary Bose excitation. In the insulating phase the energy of the boson at zero momentum is related to the jump in the chemical potential at zero doping. The dispersion of the collective modes gives rise to the structure of the incoherent Hubbard bands. A similar picture holds for the single-band Hubbard model

Machine learning for molecular dynamics with strongly correlated electrons

Abstract: We use machine learning to enable large-scale molecular dynamics (MD) of a correlated electron model under the Gutzwiller approximation scheme. This model exhibits a Mott transition as a function of on-site Coulomb repulsion $U$. The repeated solution of the Gutzwiller self-consistency equations would be prohibitively expensive for large-scale MD simulations. We show that machine learning models of the Gutzwiller potential energy can be remarkably accurate. The models, which are trained with $N=33$ atoms, enable highly accurate MD simulations at much larger scales ($N\ensuremath{\gtrsim}{10}^{3}$). We investigate the physics of the smooth Mott crossover in the fluid phase.

Mott transition in three-orbital Hubbard model with orbital splitting

Abstract: We study the Mott transition in the three-orbital Hubbard model. To investigate how the orbital level splitting and the Ising-type Hund's coupling affect the Mott transition in the case of two electrons per site, we use the dynamical mean-field theory combined with continuous-time quantum Monte Carlo simulations. The calculation of the double occupancy reveals that the critical interaction strength separating a metallic phase and two kinds of insulating phases shows a nonmonotonic behavior as a function of the level splitting. We find that this behavior is characteristic for $1/3$ filling, in comparison with the preceding results for different fillings and for two-orbital models. Strong competition between the two insulators results in an intriguing first-order transition to an insulating phase having intermediate characters between Mott and band insulators. It is also found that the two insulators show different behaviors in the phase boundary with the metallic phase in the interaction-temperature plane, which is reflected in a difference in the quasiparticle behavior around the transition. We also discuss the orbital selective Mott transition for larger Hund's coupling, which is compared with previous study at zero temperature.

Isostructural Mott transition in 2D honeycomb antiferromagnet V 0.9 PS 3

Abstract: The MPX3 family of magnetic van-der-Waals materials (M denotes a first row transition metal and X either S or Se) are currently the subject of broad and intense attention for low-dimensional magnetism and transport and also for novel device and technological applications, but the vanadium compounds have until this point not been studied beyond their basic properties. We present the observation of an isostructural Mott insulator–metal transition in van-der-Waals honeycomb antiferromagnet V0.9PS3 through high-pressure x-ray diffraction and transport measurements. We observe insulating variable-range-hopping type resistivity in V0.9PS3, with a gradual increase in effective dimensionality with increasing pressure, followed by a transition to a metallic resistivity temperature dependence between 112 and 124 kbar. The metallic state additionally shows a low-temperature upturn we tentatively attribute to the Kondo effect. A gradual structural distortion is seen between 26 and 80 kbar, but no structural change at higher pressures corresponding to the insulator–metal transition. We conclude that the insulator–metal transition occurs in the absence of any distortions to the lattice—an isostructural Mott transition in a new class of two-dimensional material, and in strong contrast to the behavior of the other MPX3 compounds.

Mott metal-insulator transition induced by utilizing a glasslike structural ordering in low-dimensional molecular conductors

Abstract: We utilize a glasslike structural transition in order to induce a Mott metal-insulator transition in the quasi-two-dimensional organic charge-transfer salt $\ensuremath{\kappa}\ensuremath{-}{\text{(BEDT-TTF)}}_{2}\mathrm{Cu}[\mathrm{N}{\text{(CN)}}_{2}\mathrm{Br}]$. In this material, the terminal ethylene groups of the BEDT-TTF molecules can adopt two different structural orientations within the crystal structure, namely eclipsed (E) and staggered (S) with the relative orientation of the outer C--C bonds being parallel and canted, respectively. These two conformations are thermally disordered at room temperature and undergo a glasslike ordering transition at ${T}_{g}\ensuremath{\sim}75$ K. When cooling through ${T}_{g}$, a small fraction that depends on the cooling rate remains frozen in the S configuration, which is of slightly higher energy, corresponding to a controllable degree of structural disorder. We demonstrate that, when thermally coupled to a low-temperature heat bath, a pulsed heating current through the sample causes a very fast relaxation with cooling rates at ${T}_{g}$ of the order of several $1000 \mathrm{K}/\mathrm{min}$. The freezing of the structural degrees of freedom causes a decrease of the electronic bandwidth $W$ with increasing cooling rate, and hence a Mott metal-insulator transition as the system crosses the critical ratio ${(W/U)}_{c}$ of bandwidth to on-site Coulomb repulsion $U$. Due to the glassy character of the transition, the effect is persistent below ${T}_{g}$ and can be reversibly repeated by melting the frozen configuration upon warming above ${T}_{g}$. Both by exploiting the characteristics of slowly changing relaxation times close to this temperature and by controlling the heating power, the materials can be fine-tuned across the Mott transition. A simple model allows for an estimate of the energy difference between the E and S state as well as the accompanying degree of frozen disorder in the population of the two orientations.