Magneto-mechanical investigation of spin dynamics in magnetic multilayers

Abstract

The Einstein-de Haas effect is used to study experimentally the interfacial spin transport in a bilayer metallic system. Specifically, mechanical torque on a permalloy film interfaced with a non-magnetic metallic film (platinum or copper), deposited on a microcantilever, is measured. The torque is generated by the transfer of the spin angular momentum from the permalloy film to the mechanical angular momentum of the cantilever. Measurement of the cantilever deflection shows that the presence of a thin non-magnetic metallic layer with strong spin-orbit interaction (platinum) changes the interfacial spin transport and causes a dramatic reduction of the mechanical torque. The observed behavior of the cantilever is attributed to the increased effective damping of the domain wall motion in the permalloy layer.

Angular momentum in spin-phonon processes

“…Emergence of micro-and nanoelectromechanical devices (MEMS and NEMS) rejuvinated interest to the problem of angular momentum in magnetomechanical systems 12 . Einstein -de Haas effect at the nanoscale has been experimentally studied in magnetic microcantilevers 13,14 and theoretically explained by the motion of domain walls 15 . Switching of magnetic moments by mechanical torques in nanocantilevers has been proposed [16][17][18] .…”

Mesoscale magnetism

“…A century ago the seminal work by Einstein and de Haas (showing that a change in magnetization results in mechanical rotation) [106] and Barnett (showing that mechanical rotation results in a magnetization change) [107] proved unambiguously that magnetic moments also possess corresponding mechanical angular momentum. This fact has gained renewed interest, since several experiments have recently shown that this angular momentum related to magnetism is large enough to significantly modify the dynamics in microelectromechanical systems (MEMS) [108,109,110]. One example is shown in Fig.…”

Spin mechanics

“…A broadband mechanical spectroscopy of the magnetic properties of one single nanostructure is clearly within reach, complementing the toolbox of mechanically detected magnetic resonance experiments [13]. This is an exciting development, all the more so as recent cantilever-based spin-mechanical experiments show that Einstein-de Haas experiments in magnetic thin films and multilayers are possible [14,15].…”