Photoswitchable Faraday effect in EuS–Au nanosystems

Abstract

Effective photoswitchable europium sulfide nanocrystals with gold nanoparticles using dithiol (DDT: 1,10‐decanedithiol) joint molecules, EuS–Au nanosystems, are demonstrated. The TEM image indicates the formation of EuS–Au nanosystems composed of cube‐shaped EuS nanocrystals and spherical Au nanoparticles. Under visible‐light irradiation, a drastic change of absorption band of EuS–Au nanosystems at around 600 nm was observed. The Faraday effects of EuS–Au nanosystems were estimated using magnetic circular dichroism (MCD) measurements. The effective change of the MCD spectra of EuS–Au nanosystems under visible‐light irradiation was successfully observed at around 670 nm for the first time. The effective reversible changes in MCD spectra with the alternative irradiation cycles of visible light (>440 nm) and dark are also presented. The decrease rate of rotation angle at 670 nm of EuS–Au nanosystems is larger than that of absorbance. These results indicate that the effective change of MCD spectra of EuS–Au nanosystems would be dominated not only by a drastic change of absorption band related to enhanced LSPR of Au nanoparticles but also by specific interaction between EuS and Au in nanosystem under irradiation.Illustration of photoswitch and TEM image of EuS–Au nanosystems.