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

Cited by in corpus (3)

• Superconducting density of states and vortex cores of 2H-NbS2
• Positions of Point-Nodes in Borocarbide Superconductor YNi2B2C
• Scanning tunnelling spectroscopy of the vortex state in NbSe2 using a superconducting tip