The Absence of Vortex Lattice Melting in a Conventional Superconductor

Abstract

The state of the vortex lattice extremely close to the superconducting to normal transition in an applied magnetic field is investigated in high purity niobium. We observe that thermal fluctuations of the order parameter broaden the superconducting to normal transition into a crossover but no sign of a first order vortex lattice melting transition is detected in measurements of the heat capacity or the small angle neutron scattering (SANS) intensity. Direct observation of the vortices via SANS always finds a well ordered vortex lattice. The fluctuation broadening is considered in terms of the Lowest Landau Level theory of critical fluctuations and scaling is found to occur over a large H_{c2}(T) range.

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Cited by in corpus (6)

• Extreme sensitivity of the vortex state in a-MoGe films to radio-frequency electromagnetic perturbation
• Disorder-induced two-step melting of vortex matter in Co-intercalated NbSe${}_2$ single crystals
• Structure and dynamics of a pinned vortex liquid in superconducting a-Re_xZr (x ~ 6) thin film
• High magnetic field studies of the Vortex Lattice structure in YBa2Cu3O7
• Estimates for the thermodynamic signatures of vortex-lattice melting in conventional superconductors
• On the nature of the phase transitions in two-dimensional type II superconductors