Resonant peak in the density of states in the normal metal / diffusive ferromagnet / superconductor junctions

TL;DR

This paper investigates the formation of zero-energy peaks in the density of states within N/I/DF/I/S junctions by solving Usadel equations, revealing how various parameters influence the DOS features.

Contribution

It provides a detailed analysis of the conditions leading to zero-energy peaks in the DOS of diffusive ferromagnet/superconductor junctions under different regimes.

Findings

Zero-energy DOS peaks depend on resistance, Thouless energy, and exchange field.

Conditions for DOS peaks are characterized for weak and strong proximity effects.

The study offers guidelines for tuning junction parameters to achieve desired DOS features.

Abstract

The conditions for the formation of zero-energy peak in the density of states (DOS) in the normal metal / insulator / diffusive ferromagnet / insulator / s-wave superconductor (N/I/DF/I/S) junctions are studied by solving the Usadel equations. The DOS of the DF is calculated in various regimes for different magnitudes of the resistance, Thouless energy and the exchange field of the DF, as well as for various resistances of the insulating barriers. The conditions for the DOS peak are formulated for the cases of weak proximity effect (large resistance of the DF/S interface) and strong proximity effect (small resistance of the DF/S interface).