Multi-Gap Superconductivity in MgB2: Magneto-Raman Spectroscopy

Abstract

Electronic Raman scattering studies on MgB2 single crystals as a function of excitation and polarization have revealed three distinct superconducting features: a clean gap below 37 cm-1 and two coherence peaks at 109 cm-1 and 78 cm-1 which we identify as the superconducting gaps in π- and σ-bands and as the Leggett's collective mode arising from the fluctuation in the relative phase between two superconducting condensates residing on corresponding bands. The temperature and field dependencies of the superconducting features have been established. A phononic Raman scattering study of the E2g boron stretching mode anharmonicity and of superconductivity induced self-energy effects is presented. We show that anharmonic two phonon decay is mainly responsible for the unusually large linewidth of the E2g mode. We observe ~2.5% hardening of the E2g phonon frequency upon cooling into the superconducting state and estimate the electron-phonon coupling strength associated with this renormalization.

Invited review in a special issue "Superconductivity in MgB_2: Physics and Applications"

References in corpus (30)

• Superconductivity of metallic boron in MgB_2
• Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps
• Inelastic Light Scattering From Correlated Electrons
• Evidence for two superconducting energy gaps in MgB2 by point-contact spectroscopy
• Phonon dispersion and electron-phonon coupling in MgB_2 and AlB_2
• Giant anharmonicity and non-linear electron-phonon coupling in MgB${}_2$; A combined first-principles calculations and neutron scattering study
• First-Principles Calculation of the Superconducting Transition in MgB2 within the Anisotropic Eliashberg Formalism
• Two-Band Superconductivity in MgB2
• Specific heat of MgB${}_2$ in a one- and a two-band model from first-principles calculations
• Vortex Imaging in the pi-Band of Magnesium Diboride
• Electronic Structure, Electron-Phonon Coupling, and Multiband Effects in MgB2
• Evidence for Two Superconducting Gaps in $Mg{B}_2$
• Direct evidence for a multiple superconducting gap in MgB2 from high-resolution photoemission spectroscopy
• Phonon Density-of-States in MgB2
• Phonon dispersion and lifetimes in MgB2
• Raman spectrum and lattice parameters of MgB2 as a function of pressure
• The Superconducting Gap in MgB_2: Electronic Raman Scattering Measurements of Single Crystals
• Effective action approach to the Leggett's mode in two-band superconductors
• MgB2 single crystals: high pressure growth and anisotropic properties
• Kohn Anomaly in MgB2 by Inelastic X-Ray Scattering
• The Dependence of Tc on Hydrostatic Pressure in Superconducting MgB2
• Electronic Raman scattering in YBCO and other superconducting cuprates
• The two colors of MgB2
• Electron-phonon coupling and phonon self-energy in MgB${}_2$: do we really understand MgB${}_2$ Raman spectra ?
• c-axis Raman Scattering in MgB2: Observation of a Dirty-Limit Gap in the pi-bands
• Electron-phonon effects on the Raman spectrum in MgB${}_2$
• Small Fermi energy, zero point fluctuations and nonadiabaticity in MgB${}_2$
• Magneto-optical reflectivity of superconducting MgB2 single crystals
• Raman scattering from a superconductivity-induced bound state in $Mg{B}_2$
• The determination of the electron-phonon interaction from tunneling data in the two-band superconductor MgB2

Cited by in corpus (10)

• Observation of Leggett's collective mode in a multi-band MgB2 superconductor
• A perspective on pnictide superconductors
• Band-selective third-harmonic generation in superconducting MgB${}_2$: Possible evidence for Higgs amplitude mode in the dirty limit
• Electron-phonon coupling in cuprate and iron-based superconductors revealed by Raman scattering
• High Tc superconductivity in CaKFe${}_4$As${}_4$ in absence of nematic fluctuations
• Anharmonic theory of superconductivity and its applications to emerging quantum materials
• Effect of interband interactions of phonon and charge fluctuation on superconducting parameters of MgB2
• Superconductivity and phonon self-energy effects in Fe${}_{1+y}$Te${}_{0.6}$Se${}_{0.4}$
• High-pressure high-temperature solution growth, structural, and superconducting properties of Fe-substituted MgB2 single crystals
• Effect of disorder on the far-infrared conductivity and on the microwave conductivity of two-band superconductors