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.

Comprehensive study of the metal-insulator transition in pulsed laser deposited epitaxial VO2 thin films

Abstract: In this paper, we present a comprehensive, correlative study of the structural, transport, optical and thermoelectric properties of high-quality VO2 thin films across its metal-insulator phase transition. Detailed x-ray diffraction study shows that it's textured polycrystalline along [010]M1, with in-plane lattice orienting along three equivalent crystallographic directions. Across the metal-insulator transition, the conductivity increases by more than 3 orders of magnitude with a value of 3.8 × 103 S/cm in the metallic phase. This increase is almost entirely accounted for by a change in electron density, while the electron mobility changes only slightly between the two phases, yet shows strong domain boundary scattering when the two phases coexist. Electron effective mass was determined to be ∼65m0 in the insulating phase. From the optical and infrared reflection spectra in the metallic phase, we obtained the plasma edge of VO2, from which the electron effective mass was determined to be ∼23m0. The bandg...

Pressure-induced heavy fermion superconductivity in the nonmagnetic quadrupolar system PrTi(2)Al(20).

Abstract: We report the discovery of a pressure-induced heavy fermion superconductivity in a nonmagnetic orbital ordering state in the cubic compound ${\mathrm{PrTi}}_{2}{\mathrm{Al}}_{20}$. In particular, we found that the transition temperature and the effective mass associated with the superconductivity are dramatically enhanced as the system approaches the putative quantum critical point of the orbital order. Our experiment indicates that the strong orbital fluctuations may provide a nonmagnetic glue for Cooper pairing.

Size-dependent electronic level structure of InAs nanocrystal quantum dots: Test of multiband effective mass theory

Abstract: The size dependence of the electronic spectrum of InAs nanocrystals ranging in radius from 10–35 A has been studied by size-selective spectroscopy An eight-band effective mass theory of the quantum size levels has been developed which describes the observed absorption level structure and transition intensities very well down to smallest crystal size using bulk band parameters This model generalizes the six-band model which works well in CdSe nanocrystals and should adequately describe most direct semiconductor nanocrystals with band edge at the Γ-point of the Brillouin zone

Large Dispersive Effects near the Band Edges of Photonic Crystals

Abstract: We have used phase-sensitive ultrashort-pulse interferometry to study the modification of optical pulse propagation near the photonic band edges in colloidal crystals consisting of polystyrene spheres in water. A strong suppression of the group velocity is found at frequencies near the $L$ gap of the fcc lattice. The group velocity dispersion diverges at the band edges and shows branches of both normal dispersion and anomalous dispersion, which can be interpreted as large changes in the effective mass, both positive and negative. We obtain excellent agreement with the dynamical diffraction theory.

Electrons in feldspar II: A consideration of the influence of conduction band-tail states on luminescence processes

Abstract: Most natural feldspars contain many charged impurities, and display a range of bond angles, distributed about the ideal. These effects can lead to complications in the structure of the conduction band, giving rise to a tail of energy states (below the high-mobility conduction band) through which electrons can travel, but with reduced mobility: transport through these states is expected to be thermally activated. The purpose of this article is twofold. Firstly, we consider what kind of lattice perturbations could give rise to both localized and extended conduction band-tail states. Secondly, we consider what influence the band tails have on the luminescence properties of feldspar, where electrons travel through the sample prior to recombination. The work highlights the dominant role that 0.04–0.05-eV phonons play in both the luminescence excitation and emission processes of these materials. It also has relevance in the dating of feldspar sediments at elevated temperatures.