Tilting instability and other anomalies in the flux-lattice in some magnetic superconductors

TL;DR

This paper investigates flux-lattice anomalies in ErNi2B2C, revealing a tilting instability near ferromagnetic transition, explaining flux lattice fluctuations and proposing further experimental studies.

Contribution

It uncovers a spontaneous tilting instability of flux lines in a magnetic superconductor and explains observed flux lattice anomalies.

Findings

Existence of flux-line tilting instability near ferromagnetic order

Enhanced flux lattice fluctuations observed

Square flux lattice phenomena explained

Abstract

The flux-line lattice in the compound $ErNi_2B_2C$, which has a tendency to ferromagnetic order in the a-b plane is studied with external magnetic field direction close to the c-axis. We show the existence of an instability where the direction of flux-lines spontaneously tilts away from that of the applied field near the onset of ferromagnetic order. The enhanced fluctuations in the flux lattice and the square flux lattice recently observed are explained and further experiments suggested.