Ubiquitous V-shape density of states in mixed state of clean limit type II superconductors; STM experiment and theory

Abstract

It is demonstrated theoretically and experimentally that the low energy density of states $N(E)$ is described by a singular V-shape form $N(E)=N_0(H)+\alpha |E|+O(E^2)$ for all clean superconductors in a vortex state, irrespective of the underlying gap structure. The linear term $\alpha |E|$ which has been not recognized so far is obtained by exactly evaluating the vortex contribution. Based on microscopic Eilenberger theory $N(E)$ is evaluated for isotropic gap, line and point node gaps to yield a V-shape $N(E)$. STS-STM experiments on NbSe${}_2$ and YNi${}_2$B${}_2$C give direct evidence for this. We provide arguments on significance of this finding and on relevance to other experiments.

5 pages, 4 figures

References in corpus (2)

• Vortices and Superfluidity in a Strongly Interacting Fermi Gas
• Specific heat and low-lying excitations in the mixed state for a type II superconductor

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• Scanning tunnelling spectroscopy of the vortex state in NbSe2 using a superconducting tip
• Theoretical studies for identifying horizontal line nodes via angle-resolved density of states measurements ---Application to Sr${}_2$RuO${}_4$---
• Exotic heavy fermion superconductivity in atomically thin CeCoIn${}_5$ films
• Hard superconducting gap and vortex-state spectroscopy in NbSe${}_2$ van der Waals tunnel junctions