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arXiv · 2605.23567

Phase diagram of the vortex state in an amorphous Re6Zr thin film exhibiting inverse melting

Pritam Das·Subhamita Sengupta·Anjan Jana·Rishabh Duhan·Sulagna Dutta·Arghya Dutta·John Jesudasan·Vivas Bagwe·Pratap Raychaudhuri
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Abstract

In Type II superconductors, the vortex lattice can exhibit "inverse melting," transitioning from a liquid to a crystalline solid as temperature increases. While recently observed via scanning tunneling microscopy in a 20 nm thick amorphous Re6Zr thin film, this work investigates the corresponding d.c. transport and low-frequency magnetic screening responses. By identifying distinct signatures of these transitions and integrating scanning tunneling spectroscopy imaging, we construct a comprehensive vortex-state phase diagram in the magnetic field-temperature parameter space. Furthermore, we demonstrate that inverse melting is thickness-dependent: a 5 nm film retains an inhomogeneous liquid state, while a 50 nm film maintains a crystalline solid structure except near the upper critical field.

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Pritam Das, Subhamita Sengupta, Anjan Jana, Rishabh Duhan, Sulagna Dutta, Arghya Dutta, John Jesudasan, Vivas Bagwe, Pratap Raychaudhuri. 2026-05-22. Phase diagram of the vortex state in an amorphous Re6Zr thin film exhibiting inverse melting. https://doi.org/10.1103/v4g9-nn57

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