Melting of the vortex lattice through intermediate hexatic fluid in a-MoGe thin film

Indranil Roy; Surajit Dutta; Aditya N. Roy Choudhury; Somak Basistha; Ilaria Maccari; Soumyajit Mandal; John Jesudasan; Vivas Bagwe; Claudio Castellani; Lara Benfatto; Pratap Raychaudhuri

doi:10.1103/physrevlett.122.047001

arXiv · 1805.05193

Melting of the vortex lattice through intermediate hexatic fluid in a-MoGe thin film

Indranil Roy·Surajit Dutta·Aditya N. Roy Choudhury·Somak Basistha·Ilaria Maccari·Soumyajit Mandal·John Jesudasan·Vivas Bagwe·Claudio Castellani·Lara Benfatto·Pratap Raychaudhuri

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Abstract

The hexatic fluid refers to a phase in between a solid and a liquid which has short range positional order but quasi-long range orientational order. In the celebrated theory of Berezinskii, Kosterlitz and Thouless and subsequently refined by Halperin, Nelson and Young, it was predicted that a 2-dimensional hexagonal solid can melt in two steps: first, through a transformation from a solid to a hexatic fluid which retains quasi long range orientational order and then from a hexatic fluid to an isotropic liquid. In this paper, using a combination of real space imaging and transport measurements we show that the 2-dimensional vortex lattice in a-MoGe thin film follows this sequence of melting as the magnetic field is increased. Identifying the signatures of various transitions on the bulk transport properties of the superconductor, we construct a vortex phase diagram for a two dimensional superconductor.

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Indranil Roy, Surajit Dutta, Aditya N. Roy Choudhury, Somak Basistha, Ilaria Maccari, Soumyajit Mandal, John Jesudasan, Vivas Bagwe, Claudio Castellani, Lara Benfatto, Pratap Raychaudhuri. 2018-08-31. Melting of the vortex lattice through intermediate hexatic fluid in a-MoGe thin film. https://doi.org/10.1103/physrevlett.122.047001

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