Perfect optical absorption-enhanced magneto-optic Kerr effect microscopy

TL;DR

This paper demonstrates that perfect optical absorption significantly enhances magneto-optic Kerr effect microscopy, enabling high-sensitivity, real-time imaging of nanoscale magnetic domains with improved performance and new functionalities.

Contribution

The study introduces the use of perfect optical absorption to boost MOKE microscopy, achieving larger Kerr signals and enabling analyser-free and real-time magnetic domain imaging.

Findings

Kerr amplitude up to 20 degrees for 1-nm Co film

Magnetic domain imaging visibility of 0.47

Real-time detection of sub-wavelength magnetic domain reversals

Abstract

Magnetic and spintronic media have offered fundamental scientific subjects and technological applications. Magneto-optic Kerr effect (MOKE) microscopy provides the most accessible platform to study the dynamics of spins, magnetic quasi-particles, and domain walls. However, in the research of nanoscale spin textures and state-of-the-art spintronic devices, optical techniques are generally restricted by the extremely weak magneto-optical activity and diffraction limit. Highly sophisticated, expensive electron microscopy and scanning probe methods thus have come to the forefront. Here, we show that perfect optical absorption (POA) dramatically improves the performance and functionality of MOKE microscopy. For 1-nm-thin Co film, we demonstrate a Kerr amplitude as large as 20 degree and magnetic domain imaging visibility of 0.47. Especially, POA-enhanced MOKE microscopy enables real-time detection and statistical analysis of sub-wavelength magnetic domain reversals. Furthermore, we exploit enhanced magneto-optic birefringence and demonstrate analyser-free MOKE microscopy. The POA technique is promising for optical investigations and applications of nanomagnetic systems.