title: Atomic spin-sensitive dissipation on magnetic surfaces.
abstract: We identify the mechanism of energy dissipation relevant to spin-sensitive nanomechanics including the recently introduced magnetic exchange force microscopy, where oscillating magnetic tips approach surface atomic spins. The tip-surface exchange couples spin and atom coordinates, leading to a spin-phonon problem with Caldeira-Leggett-type dissipation. In the overdamped regime, that can lead to a hysteretic flip of the local spin with a large spin-dependent dissipation, even down to the very low experimental tip oscillation frequencies, describing recent observations for Fe tips on NiO. A phase transition to an underdamped regime with dramatic drop of magnetic tip dissipation should in principle be possible by tuning tip-surface distance.
authors.affiliation: International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Pellegrini
authors.forename: Giuseppe E
authors.initials: GE
authors.lastname: Santoro
authors.forename: Erio
authors.initials: E
authors.lastname: Tosatti