Damping of micromechanical structures by paramagnetic relaxation

TL;DR

This paper investigates how the relaxation dynamics of paramagnetic ions within micromechanical cantilevers influence their damping, revealing a new intrinsic dissipation mechanism and potential for probing magnetic relaxation.

Contribution

It demonstrates the sensitivity of micromechanical cantilever damping to paramagnetic relaxation dynamics and identifies a novel intrinsic dissipation source.

Findings

Damping is enhanced by the interplay of magnetic anisotropy and relaxation rates.

Damping varies with temperature, magnetic field, and vibrational mode.

The effect can be used to probe magnetic relaxation behavior.

Abstract

We find that the damping of micromechanical cantilevers is sensitive to the relaxation dynamics of paramagnetic ions contained within the levers. We measure cantilevers containing paramagnetic Mn ions as a function of temperature, magnetic field, and the vibrational mode of the lever and find that the levers damping is strongly enhanced by the interplay between the motion of the lever, the ions magnetic anisotropy, and the ratio of the ions longitudinal relaxation rate to the resonance frequency of the cantilever. This enhancement can improve the levers ability to probe the relaxation behavior of paramagnetic or superparamagetic systems; it may also represent a previously unrecognized source of intrinsic dissipation in micromechanical structures.