Phase-sensitive imaging of ferromagnetic resonance using ultrafast heat pulses

TL;DR

This paper introduces a phase-sensitive imaging method using ultrafast heat pulses and TRANE microscopy to map local magnetization dynamics and RF current phases in patterned magnetic structures, enhancing spatial resolution.

Contribution

The study presents a novel phase-sensitive imaging technique combining picosecond laser heating and TRANE microscopy for detailed FMR and RF current phase mapping.

Findings

Spatial variation of RF current and FMR precession observed in nonuniform samples.

Both amplitude and phase of FMR precession closely relate to RF current phase.

Method enables detailed local magnetization dynamics imaging.

Abstract

Measuring local magnetization dynamics and its spatial variation is essential for advancements in spintronics and relevant applications. Here we demonstrate a phase-sensitive imaging technique for studying patterned magnetic structures based on picosecond laser heating. With the time-resolved anomalous Nernst effect (TRANE) and extensions, we simultaneously image the dynamic magnetization and RF driving current density. The stroboscopic detection implemented in TRANE microscopy provides access to both amplitude and phase information of ferromagnetic resonance (FMR) and RF current. Using this approach, we measure the spatial variation of the Oersted driving field angle across a uniform channel. In a spatially nonuniform sample with a cross shape, a strong spatial variation for the RF current as well as FMR precession is observed. We find that both the amplitude and the phase of local FMR precession are closely related to those of the RF current.