Browsing by Author "Lortz, R."

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Thermal fluctuations and vortex melting in the Nb3Sn superconductor from high resolution specific heat measurements
(2006-09-01)
Lortz, R.
;
Lin, F.
;
Musolino, N.
;
Wang, Y.
;
Junod, A.
The range of critical thermal fluctuations in "classical" bulk superconductors is extremely small and especially in low fields hardly experimentally accessible. With a new type of calorimeter we have been able to resolve a small lambda anomaly within a narrow temperature range around the H-c2 line. We show that the evolution of the anomaly as a function of magnetic field follows scaling laws expected in the presence of critical fluctuations. The lower onset of the fluctuation regime shows many characteristics of a continuous solid-to-liquid transition in the vortex matter. It can be driven into a first-order vortex melting transition by a small ac field which helps the vortex matter to reach equilibrium.