Melting of vortex lattice in magnetic iron-pnictide superconductor RbEuFe<sub>4</sub>As<sub>4</sub>
ORAL
Abstract
The iron-based superconductors are characterized by sizable thermal fluctuations due to high transition temperatures and small coherence lengths. We report calorimetric and transport observations for the vortex-lattice melting in the magnetic iron-pnictide superconductor RbEuFe4As4 with Tc ≈ 37K and dHc2/dT ≈ 4T/K. The melting transition is seen as a sharp drop of the resistivity and a step of the specific heat at the magnetic-field-dependent temperature. The typical step height is ∼ 4-5% of the zero-field jump, similar to YBa2Cu3O7 and in agreement with theoretical estimates. The specific-heat peak due to the latent heat expected for very clean materials, however, was not observed. The melting line lies in the temperature/magnetic-field plane noticeably below the upper-critical-field line, and the vortex-liquid state occupies a significant portion of the phase diagram. The location of the melting transition is in quantitative agreement with theoretical predictions without fitting parameters.
*This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. K.W. and R.W. acknowledge support from the Swiss National Science Foundation through an Early Postdoc Mobility fellowship.
–
Presenters
-
Alexei E Koshelev
- Materials Science Division, Argonne National Laboratory
- Argonne National Laboratory