Temperature dependent anisotropy of the penetration depth and coherence length in MgB$_2

Abstract

We report measurements of the temperature dependent anisotropies (${\gamma }_{\lambda }$ and ${\gamma }_{\xi }$) of both the London penetration depth $\lambda$ and the upper critical field of MgB${}_2$. Data for ${\gamma }_{\lambda }={\lambda }_c/{\lambda }_a$ was obtained from measurements of ${\lambda }_a$ and ${\lambda }_c$ on a single crystal sample using a tunnel diode oscillator technique. ${\gamma }_{\xi }=H_{c2}^{\parallel c}/H_{c2}^{\perp c}$ was deduced from field dependent specific heat measurements on the same sample. ${\gamma }_{\lambda }$ and ${\gamma }_{\xi }$ have opposite temperature dependencies, but close to $T_c$ tend to a common value (${\gamma }_{\lambda }\simeq {\gamma }_{\xi }=1.75\pm 0.05$). These results are in good agreement with theories accounting for the two gap nature of MgB${}_2$

4 pages with figures (New version)

References in corpus (20)

• Superconductivity of metallic boron in MgB_2
• Phenomenological two-gap model for the specific heat of MgB_2
• Multiband model for tunneling in MgB2 junctions
• Temperature and field dependence of the anisotropy of MgB2
• Electronic Structure, Electron-Phonon Coupling, and Multiband Effects in MgB2
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• Anisotropies of the lower and upper critical fields in MgB${}_2$ single crystals
• Anisotropy of the upper critical field in superconductors with anisotropic gaps. Anisotropy parameters of MgB2
• MgB2 single crystals: high pressure growth and anisotropic properties
• Muon-spin-relaxation study of the magnetic penetration depth in MgB2
• Absence of non-linear Meissner effect in YBa2Cu3O6.95
• Two-band Effects in the Angular Dependence of Hc2 of MgB2 Single Crystals
• Quasiparticle Excitations outside the Vortex Cores in MgB${}_2$ Probed by Muon Spin Rotation
• Damping of the de Haas-van Alphen oscillations in the superconducting state of MgB_2

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