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Effective mass (solid-state physics)

About: Effective mass (solid-state physics) is a research topic. Over the lifetime, 12539 publications have been published within this topic receiving 295485 citations.


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Journal ArticleDOI
16 Sep 2021-Nature
TL;DR: In this paper, the interaction strength of the MoTe2/WSe2 superlattices was tuned to drive a continuous metal-to-insulator transition at a fixed electron density, which is consistent with the universal critical theory of a continuous Mott transition in two dimensions.
Abstract: The evolution of a Landau Fermi liquid into a non-magnetic Mott insulator with increasing electronic interactions is one of the most puzzling quantum phase transitions in physics1–6. The vicinity of the transition is believed to host exotic states of matter such as quantum spin liquids4–7, exciton condensates8 and unconventional superconductivity1. Semiconductor moire materials realize a highly controllable Hubbard model simulator on a triangular lattice9–22, providing a unique opportunity to drive a metal–insulator transition (MIT) via continuous tuning of the electronic interactions. Here, by electrically tuning the effective interaction strength in MoTe2/WSe2 moire superlattices, we observe a continuous MIT at a fixed filling of one electron per unit cell. The existence of quantum criticality is supported by the scaling collapse of the resistance, a continuously vanishing charge gap as the critical point is approached from the insulating side, and a diverging quasiparticle effective mass from the metallic side. We also observe a smooth evolution of the magnetic susceptibility across the MIT and no evidence of long-range magnetic order down to ~5% of the Curie–Weiss temperature. This signals an abundance of low-energy spinful excitations on the insulating side that is further corroborated by the Pomeranchuk effect observed on the metallic side. Our results are consistent with the universal critical theory of a continuous Mott transition in two dimensions4,23. The interaction strength in moire superlattices is tuned to drive a continuous metal-to-insulator transition at a fixed electron density.

110 citations

Journal ArticleDOI
TL;DR: The possibility of superconductivity with the aid of the plasmon in two-and three-dimensional single-carrier systems is investigated by numerical solutions of the gap equation in the weak-coupling theory of super-conductivity as discussed by the authors.
Abstract: The possibility of the superconductive state with the aid of the plasmon in two- and three-dimensional single-carrier systems is investigated by numerical solutions of the gap equation in the weak-coupling theory of superconductivity, in which the effective interactions are calculated in the plasmon-pole approximation. The superconductivity does appear in rather low carrier concentrations and the highest attainable transition temperature is of the order of m * /κ 2 degrees Kelvin, where the effective mass, m * , is in the unit of the mass of a free electron and κ is the dielectric constant. Compared with a three-dimensional system, a two-dimensional one is more favorable for the plasmon mechanism of superconductivity, which stems from the difference in the dispersion relation of the plasmon.

110 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the electronic and thermodynamic properties of β-Ga2O3 in the framework of density functional theory and obtained the equilibrium structural parameters and Debye temperature through fitting of the energy surface to the equation of state.
Abstract: Electronic and thermodynamic properties of β-Ga2O3 are investigated in the framework of density functional theory. The equilibrium structural parameters and Debye temperature are obtained through fitting of the energy surface to the equation of state. Analysis of the band structure shows the valence band maximum to be degenerate at Γ and M, whereas the conduction band minimum is predicted to be at Γ. The valence band is almost flat, indicating a rather large effective mass for holes, whereas the calculated electron effective mass comes out to be about 0.12, expressed in units of the free electron mass.

110 citations

Journal ArticleDOI
TL;DR: In this article, resistivity, Hall coefficient, and magnetoresistance were studied for n and p-type GaSb, and the infrared absorption edge was investigated using relatively pure p−type, degenerate n−type and compensated samples.
Abstract: Resistivity, Hall coefficient, and magnetoresistance were studied for n‐ and p‐type GaSb. The infrared absorption edge was investigated using relatively pure p‐type, degenerate n‐type, and compensated samples. Infrared absorption of carriers and the effect of carriers on the reflectivity were studied. The magnetoresistance as a function of Hall coefficient for n‐type samples at 4.2°K gave clear evidence for a second energy minimum lying above the edge of the conduction band; the energy separation is equal to the Fermi energy for a Hall coefficient of 5 cm3/coulomb. The shift of absorption edge in n‐type samples showed that the conduction band has a single valley at the edge, with a density‐of‐state mass md1=0.052 m. By combining the results on the edge shift, magnetoresistance, and Hall coefficient, it was possible to deduce: the density‐of‐states mass ratio md2/md1=17.3, the mobility ratio μ2/μ1=0.06, and the energy separation Δ=0.08 ev between the two sets of valleys at 4.2°K. Anisotropy of magnetoresistance, observed at 300°K, showed that the higher valleys are situated along (111) directions. The infrared reflectivity of n‐type samples can be used to deduce the anisotropy of the higher valleys; tentative estimates were obtained. Infrared reflectivity gave an estimate of 0.23 m for the effective mass of holes. The variation of Hall coefficient and transverse magnetoresistance with magnetic field and the infrared absorption spectrum of holes showed the presence of two types of holes. Appreciable anisotropy of magnetoresistance was observed in a p‐type sample, indicating that the heavy hole band is not isotropic; this was confirmed by the infrared absorption spectrum of holes. The results on the absorption edge in various samples seemed to indicate that the maximum of the valence band is not at k=0. However, it appears likely that transitions from impurity states near the valence band produced absorption beyond the threshold of direct transitions.

109 citations

Journal ArticleDOI
TL;DR: In the future, the use of photonic rhombic lattices, together with the successful implementation of a synthetic gauge field, will enable the observation of Aharonov-Bohm photonic caging.
Abstract: We experimentally demonstrate the photonic realization of a dispersionless flat band in a quasi-one-dimensional photonic lattice fabricated by ultrafast laser inscription. In the nearest neighbor tight binding approximation, the lattice supports two dispersive and one nondispersive (flat) band. We experimentally excite superpositions of flat-band eigenmodes at the input of the photonic lattice and show the diffractionless propagation of the input states due to their infinite effective mass. In the future, the use of photonic rhombic lattices, together with the successful implementation of a synthetic gauge field, will enable the observation of Aharonov-Bohm photonic caging.

109 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202215
2021410
2020421
2019395
2018362
2017412