Magnetic friction in Ising spin systems

TL;DR

This paper predicts magnetic friction in Ising spin systems caused by magnetic correlations, showing it depends on temperature, coupling type, and can even cool spins near the surface under certain conditions.

Contribution

It introduces the concept of magnetic friction in Ising systems and analyzes its dependence on temperature, coupling, and motion, revealing novel effects like spin cooling.

Findings

Magnetic friction peaks near the critical temperature.

Antiferromagnetic coupling results in stronger friction.

Relative motion can cool spins near the surface in the ordered phase.

Abstract

A new contribution to friction is predicted to occur in systems with magnetic correlations: Tangential relative motion of two Ising spin systems pumps energy into the magnetic degrees of freedom. This leads to a friction force proportional to the area of contact. The velocity and temperature dependence of this force are investigated. Magnetic friction is strongest near the critical temperature, below which the spin systems order spontaneously. Antiferromagnetic coupling leads to stronger friction than ferromagnetic coupling with the same exchange constant. The basic dissipation mechanism is explained. If the coupling of the spin system to the heat bath is weak, a surprising effect is observed in the ordered phase: The relative motion acts like a heat pump cooling the spins in the vicinity of the friction surface.