scispace - formally typeset
Search or ask a question
Topic

Free electron model

About: Free electron model is a research topic. Over the lifetime, 4678 publications have been published within this topic receiving 103535 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the effect of free electrons on the optical phonon of silicon at the center of the Brillouin zone is studied using the Raman scattering technique, and the profile factor which is related to disymetry is shown to have the signes of the matrix elements of the electron-phonon interaction.

37 citations

Posted Content
TL;DR: Transport and ARPES reveal extremely good metallicity arising from almost free-electron behavior in single-crystal PtCoO2, establishing Pt coO2 as a model nearly-free–electron system in a 5d delafossite transition-metal oxide.
Abstract: Understanding the role of electron correlations in strong spin-orbit transition-metal oxides is key to the realisation of numerous exotic phases including spin-orbit assisted Mott insulators, correlated topological solids, and prospective new high-temperature superconductors. To date, most attention has been focussed on the $5d$ iridium-based oxides. Here, we instead consider the Pt-based delafossite oxide PtCoO$_2$. Our transport measurements, performed on single-crystal samples etched to well-defined geometries using focussed ion-beam techniques, yield a room-temperature resistivity of only 2.1~$\mu\Omega$cm, establishing PtCoO$_2$ as the most conductive oxide known. From angle-resolved photoemission and density-functional theory, we show that the underlying Fermi surface is a single cylinder of nearly hexagonal cross-section, with very weak dispersion along k$_z$. Despite being predominantly composed of $d$-orbital character, the conduction band is remarkably steep, with an average effective mass of only 1.14$m_e$. Moreover, the sharp spectral features observed in photoemission remain well-defined with little additional broadening for over 500~meV below E$_F$, pointing to suppressed electron-electron scattering. Together, our findings establish PtCoO$_2$ as a model nearly-free electron system in a $5d$ delafossite transition-metal oxide.

37 citations

Journal ArticleDOI
TL;DR: In this paper, a time-resolved RSXD experiment from the prototypical correlated electron material magnetite using soft x-ray pulses from the free-electron laser FLASH in Hamburg is presented.
Abstract: Resonant soft x-ray diffraction (RSXD) with femtosecond (fs) time resolution is a powerful tool for disentangling the interplay between different degrees of freedom in strongly correlated electron materials. It allows addressing the coupling of particular degrees of freedom upon an external selective perturbation, e.g., by an optical or infrared laser pulse. Here, we report a time-resolved RSXD experiment from the prototypical correlated electron material magnetite using soft x-ray pulses from the free-electron laser FLASH in Hamburg. We observe ultrafast melting of the charge-orbital order leading to the formation of a transient phase, which has not been observed in equilibrium.

37 citations

Journal ArticleDOI
TL;DR: In this article, the anisotropic properties of YBa2Cu4O8 have been investigated using the Montgomery formalism for anisotropies using single crystal platelets by optical and electron transport measurements.
Abstract: The anisotropy within the a-b plane of YBa2Cu4O8 has been studied on single crystal platelets by optical and electron transport measurements. The optical investigations include polarized reflectivity measurements at room temperature for photon energies between 0.5 and 4 eV and a direct measurement of the ratio of the reflectivity coefficients r b r a . The anisotropy of the electrical resistivity has been determined from AC van der Pauw measurements using the Montgomery formalism for anisotropic materials. The optical reflectivity spectra are dominated by Drude-like free electron contributions with plasmon energies of 2.8 eV and 1.67 eV for the electrical field vector along the b- and a-axis, respectively. The electrical resistivity displays an anisotropy of a factor of about 3. The superconducting transition temperature (midpoint of the resistivity drop) is 76 K. Contrary to YBa2Cu3O7, clear deviations from linear temperature dependences of the resistivity are observed in the normal state of YBa2Cu4O8. An extrapolation of the linear (normal) part gives zero resistance at 36 ± 2 K and not 0 K. The observed anisotropies are compared with results of a tight binding calculation.

37 citations

Journal ArticleDOI
TL;DR: The optical properties of gallium quench condensed onto substrates at 10K, 30K and 80K have been studied in this article, where it was found that films condensed at 10k had a spectrum which could be described extremely well by the Drude equations.
Abstract: The optical properties of gallium quench condensed onto substrates at 10K, 30K and 80K have been studied. It is found that films condensed at 10K had a spectrum which could be described extremely well by the Drude equations. At higher temperatures two different spectra were observed, which the authors believe belong to the orthorhombic alpha dn and the monoclinic beta phases of gallium.

37 citations


Network Information
Related Topics (5)
Electron
111.1K papers, 2.1M citations
95% related
Excited state
102.2K papers, 2.2M citations
91% related
Band gap
86.8K papers, 2.2M citations
90% related
Scattering
152.3K papers, 3M citations
89% related
Magnetic field
167.5K papers, 2.3M citations
89% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202340
202290
2021132
2020122
2019114
2018112