Anisotropy of the Sommerfeld Coefficient in Magnesium Diboride Single Crystals
Z. Pribulova, T. Klein, J. Marcus, C. Marcenat, F. Levy, M. S. Park, H. G. Lee, B. W. Kang, S. I. Lee, S. Tajima, S. Lee
DOI 10.1103/PhysRevLett.98.137001 · Physical Review Letters
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Abstract
The anisotropic field dependence of the Sommerfeld coefficient γ has been measured down to B→0 by combining specific heat and Hall probe magnetization measurements in MgB2 single crystals. We find that γ(B,θ) is the sum of two contributions arising from the σ and π band, respectively. We show that γσ(B,θ)=B/Bc2(θ) where Bc2(θ)=Bc2ab/sin2θ+Γ2cos2θ with Γ∼5.4 (θ being the angle between the applied field and the c axis) and γπ(B,θ)=γπ(B)=B/Bπ(B). The “critical field” of the π band Bπ is fully isotropic but field dependent increasing from ∼0.25 T for B≤0.1 T up to 3 T ∼Bc2c for B→3 T. Because of the coupling of the two bands, superconductivity survives in the π band up to 3 T but is totally destroyed above for any orientation of the field.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
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