Temperature dependence of the tunneling spectrum near a vortex core

We propose a simple model to account for the anomaly observed in the tunneling conductance at a vortex core in NbSe2 by Hess et al. The sharp peak occurring at low bias is attributed to self-energy corrections of the normal electrons in the core caused by their coupling to superconducting excitations outside the core. The temperature dependence of the tunneling spectrum is calculated, and the low-bias peak is found to increase significantly at reduced temperature. However, the width hardly changes, but the dips on each side of the low-bias peak become more pronounced. Finally, we show that an appropriate (spatially dependent) admixture of the tunneling spectrum at the vortex center with the spectrum two coherence lengths away explains the position dependence of the tunneling conductance.