Magnetoelastic excitation of single nanomagnets for optical measurement of intrinsic Gilbert damping

Abstract

We report a novel all-optical technique to drive and probe the spin dynamics of single nanomagnets. Optically generated surface acoustic waves (SAWs) drive the magnetization precession in nanomagnets via magneto-elastic (MEL) coupling. We investigate the field-swept dynamics of isolated Ni nanomagnets at various SAW frequencies, and show that this method can be used to accurately determine the intrinsic Gilbert damping of nanostructured magnetic materials. This technique opens a new avenue for studying the spin dynamics of nanoscale devices using non-thermal ("cold") excitation, enabling direct observation of the MEL driven dynamics.

Preferential excitation of a single nanomagnet using magnetoelastic coupling

“…One method of exciting ferromagnetic resonance that has become increasingly popular uses radio-frequency acoustic pulses, known as surface acoustic waves (SAWs), to resonantly excite spin dynamics via the magneto-elastic effect (MEL), also known as the inverse magnetostrictive effect. [13][14][15][16][17] The acoustic pulses periodically deform the magnetic sample in time and space, which in turn generates an internal MEL field that oscillates at the SAW frequency. However, only few studies have investigated the transient response of single nanomagnets driven by SAWs [17,18], although such studies are crucial to the development of nanoscale magnetomechanical devices because they reveal the intrinsic magnetic properties that underpin the MEL interaction.…”

“…[13][14][15][16][17] The acoustic pulses periodically deform the magnetic sample in time and space, which in turn generates an internal MEL field that oscillates at the SAW frequency. However, only few studies have investigated the transient response of single nanomagnets driven by SAWs [17,18], although such studies are crucial to the development of nanoscale magnetomechanical devices because they reveal the intrinsic magnetic properties that underpin the MEL interaction. [8,17,19] Recently, we introduced a novel all-optical technique that utilizes nonlocally generated SAWs to athermally drive spin dynamics in a remote, single nanomagnet.…”

“…However, only few studies have investigated the transient response of single nanomagnets driven by SAWs [17,18], although such studies are crucial to the development of nanoscale magnetomechanical devices because they reveal the intrinsic magnetic properties that underpin the MEL interaction. [8,17,19] Recently, we introduced a novel all-optical technique that utilizes nonlocally generated SAWs to athermally drive spin dynamics in a remote, single nanomagnet. [17] Using this method, we reported the first time-resolved measurements of the SAW driven magnetization precession of a single magnetic nanostructure and showed that this technique can be used to directly determine the intrinsic Gilbert damping of the nanomagnet.…”

“…[8,17,19] Recently, we introduced a novel all-optical technique that utilizes nonlocally generated SAWs to athermally drive spin dynamics in a remote, single nanomagnet. [17] Using this method, we reported the first time-resolved measurements of the SAW driven magnetization precession of a single magnetic nanostructure and showed that this technique can be used to directly determine the intrinsic Gilbert damping of the nanomagnet. [17] In this work, we demonstrate that SAWs can be used to selectively excite spin dynamics in two identical, elliptical nanomagnets with orthogonal orientations.…”

“…[17] Using this method, we reported the first time-resolved measurements of the SAW driven magnetization precession of a single magnetic nanostructure and showed that this technique can be used to directly determine the intrinsic Gilbert damping of the nanomagnet. [17] In this work, we demonstrate that SAWs can be used to selectively excite spin dynamics in two identical, elliptical nanomagnets with orthogonal orientations. We observe the amplitude and damping rate of the MEL-driven precession depend on the direction of the SAW and sample geometry.…”