Imaging the Magnetization of Single Magnetite NanoparticleClusters via Photothermal Circular Dichroism

Magnetic imaging is a versatile tool in biological andcondensed-matter physics. Existing magnetic imaging techniqueseither require demanding experimental conditions which restrict therange of their applications or lack the spatial resolution required forsingle-particle measurements. Here, we combine photothermal (PT)microscopy with magnetic circular dichroism (MCD) to develop aversatile magnetic imaging technique using visible light. Unlike mostmagnetic imaging techniques, photothermal magnetic circulardichroism (PT MCD) microscopy works particularly well for singlenanoparticles immersed in liquids. As a proof of principle, wedemonstrate magnetic CD imaging of superparamagnetic magnetitenanoparticulate clusters immersed in microscope immersion oil. Thesensitivity of our method allowed us to probe the magnetizationcurve of single similar to 400-nm-diameter magnetite nanoparticulate clusters

Automated summary

Magnetic imaging is a versatile tool in the fields of biological and condensed-matter physics. However, existing techniques have limitations. This study combines photothermal microscopy with magnetic circular dichroism to develop a versatile magnetic imaging technique using visible light. The method works particularly well for single nanoparticles in liquids and allows for magnetic circular dichroism imaging.