Spectroscopic Evidence for Anisotropic S-Wave Pairing Symmetry in MgB2

Abstract

Scanning tunneling spectroscopy of superconducting MgB${}_2$ ($T_c=39$ K) were studied on high-density pellets and c-axis oriented films. The sample surfaces were chemically etched to remove surface carbonates and hydroxides, and the data were compared with calculated spectra for all symmetry-allowed pairing channels. The pairing potential (${\Delta }_k$) is best described by an anisotropic s-wave pairing model, with ${\Delta }_k={\Delta }_{xy}{\sin }^2{\theta }_k+{\Delta }_z{\cos }^2{\theta }_k$, where ${\theta }_k$ is the angle relative to the crystalline c-axis, ${\Delta }_z\sim 8.0$ meV, and ${\Delta }_{xy}\sim 5.0$ meV.

4 pages and 3 figures. Submitted to Physical Review Letters. Corresponding author: Nai-Chang Yeh (e-mail: [email protected])

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• Reflection of two-gap nature in penetration depth measurements of MgB${}_2$ film
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• Break-Junction Tunneling on MgB_2
• Strong Coupling and Double Gap Density of States in Superconducting MgB2
• Far-infrared transmission studies of c-axis oriented superconducting MgB2 thin film
• Reversible magnetization of MgB2 single crystals with a two-gap nature
• Effects of unreacted Mg impurities on the transport properties of MgB2
• Superconducting energy gap distribution in c-axis oriented MgB${}_2$ thin film from point contact study
• Anisotropic s-wave superconductivity: comparison with experiments on MgB2 single crystals
• Strongly Anisotropic s-Wave Gaps in Exotic Superconductors
• Magneto-optical reflectivity of superconducting MgB2 single crystals
• Reversible magnetization measurement of the anisotropy of the London penetration depth in MgB2 single crystals
• Fluctuation Study of the Specific Heat of MgB2
• Complicated nature of the gap in MgB2: magnetic field-dependent optical studies
• Temperature and junction-type dependency of Andreev reflection in MgB2
• Heat capacity of mesoscopically disordered superconductors:implications to MgB${}_2$
• Pressure Effects and Large Polarons in Layered MgB_2 Superconductor
• Is Delta_{pi}-gap-only superconductivity possible in Mg_{1-x}Al_{x}B_{2} and Mg(B_{1-y}C_{y})_{2} alloys?