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.
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