Discrete energy levels of Caroli-de Gennes-Matricon states in quantum limit in FeTe0.55Se0.45

Mingyang Chen; Xiaoyu Chen; Huan Yang; Zengyi Du; Xiyu Zhu; Enyu Wang; Hai-Hu Wen

doi:10.1038/s41467-018-03404-8

Discrete energy levels of Caroli-de Gennes-Matricon states in quantum limit in FeTe_0.55Se_0.45

Nat Commun. 2018 Mar 6;9(1):970. doi: 10.1038/s41467-018-03404-8.

Authors

Mingyang Chen¹, Xiaoyu Chen¹, Huan Yang², Zengyi Du¹, Xiyu Zhu¹, Enyu Wang¹, Hai-Hu Wen³

Affiliations

¹ Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
² Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, 210093, Nanjing, China. huanyang@nju.edu.cn.
³ Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, 210093, Nanjing, China. hhwen@nju.edu.cn.

Abstract

Caroli-de Gennes-Matricon (CdGM) states were predicted in 1964 as low-energy excitations within vortex cores of type-II superconductors. In the quantum limit, the energy levels of these states were predicted to be discrete with the basic levels at ±μΔ²/E_F (μ = 1/2, 3/2, 5/2, …) with Δ the superconducting energy gap and E_F the Fermi energy. However, due to the small ratio of Δ/E_F in most type-II superconductors, it is very difficult to observe the discrete CdGM states, but rather a symmetric peak which appears at zero bias at the vortex center. Here we report the clear observation of these discrete energy levels of CdGM states in FeTe_0.55Se_0.45. The rather stable energies of these bound state peaks vs. space clearly validate our conclusion. Analysis based on the energies of these CdGM states indicates that the Fermi energy in the present system is very small.

Publication types

Research Support, Non-U.S. Gov't