Specific Heat of HfV_2: Effect of Magnetic Fields
Abstract
Specific-heat (C) measurements on a single crystal of HfV2 were made from 1 to 300 K in magnetic fields (H) along the [110] axis to 14 T. HfV2 has a martensitic transition at TM = 118 K and becomes superconducting (SC) at Tc ∼8 K. Tc is shifted and C varies following repeated cooling cycles from room temperature. This variation is probably related to an incomplete structural transition from cubic to orthorhombic at T_M. For zero field ΔC(T_c)/γTc = 2.07, is nearly independent of variations in Tc and C, which indicates strong coupling. The SC state C can be fitted with the alpha model for strong coupling using an energy gap Δ(0)/k_BTc = 2.1. In the normal state, the Sommerfeld constant (γ) depends on thermal history: for Tc = 8.0 K, γn = 42.1 mJ K-2 mol-1. When H > 0 the SC anomaly shifts to lower T. The mixed state γ is linear in H with a slope that is a function of thermal history. Extrapolating γ to γn yields an upper critical field H_c2 ∼30 T. From fits above Tc the Debye theta, characterizing the lattice C, is 177 K.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MAR.C1146F