Superconducting energy gap in MgB2 film observed by infrared reflectance

Abstract

Far-infrared reflectance of a MgB2 film has been measured by Fourier-transform spectroscopy for frequencies 10 cm^{-1}<ν<4000 cm^{-1} above and below the superconducting transition. The data provide clear experimental evidence for the onset of a superconducting gap at 24 cm^{-1} at T=5 K. On increasing temperature the gap energy increases, contrary to what is expected in isotropic BCS superconductors. The small zero-temperature gap value and its unconventional increases on increasing temperature can only be explained by a highly anisotropic or multiple gap function.

5 pages, figures included

References in corpus (19)

• Superconductivity of metallic boron in MgB_2
• Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps
• Specific Heat of Mg ^{11}B_2
• Two Gap State Density in MgB${}_2$: A True Bulk Property or A Proximity Effect?
• Specific heat in the superconducting and normal state (2-300 K, 0-16 Teslas), and magnetic susceptibility of the 38-K superconductor MgB2: evidence for a multicomponent gap
• Direct evidence for a multiple superconducting gap in MgB2 from high-resolution photoemission spectroscopy
• Scanning Tunneling Spectroscopy in MgB2
• Tunneling spectroscopy in small grains of superconducting MgB2
• Exponential Temperature Dependence of Penetration Depth in Single Crystal MgB_2
• High-Resolution Photoemission Study of MgB2
• Far-infrared optical conductivity gap in superconducting MgB2 films
• Energy Gap from Tunneling and Metallic Sharvin Contacts onto MgB2: Evidence for a Weakened Surface Layer
• Tunneling spectroscopy measurement of the superconductor gap parameter of MgB_2
• Strong Electron-Phonon Coupling in Superconducting MgB${}_2$: A Specific Heat Study
• Optical conductivity and penetration depth in MgB2
• Anisotropic s-wave superconductivity in MgB_2
• Far-infrared transmission studies of c-axis oriented superconducting MgB2 thin film
• Surface effects in multiband superconductors. Application to MgB${}_2$
• Optical measurements of the superconducting gap in MgB2

Cited by in corpus (13)

• Electrodynamics of Correlated Electron Materials
• Terahertz Conductivity at the Verwey Transition in Magnetite
• The two colors of MgB2
• Multiband and impurity effects in infrared and optical spectra of MgB2
• Anisotropic s-wave superconductivity: comparison with experiments on MgB2 single crystals
• Clean and Dirty Superconductivity in Pure, Al doped, and Neutron Irradiated MgB2: a Far-Infrared Study
• Magneto-optical reflectivity of superconducting MgB2 single crystals
• Looking at the superconducting gap of iron pnictides
• On the peak in the far-infrared conductivity of strongly anisotropic cuprates
• Reentrant phases in electron-doped ${\text{EuFe}}_2{\text{As}}_2$: spin glass and superconductivity
• Heat capacity of mesoscopically disordered superconductors:implications to MgB${}_2$
• Far-infrared and submillimeter-wave conductivity in electron-doped cuprate La_{2-x}Ce_xCuO_4
• Effect of disorder on the far-infrared conductivity and on the microwave conductivity of two-band superconductors