Photoinduced Bidirectional Magnetism against Monodirectional Electronics in Square-Antiprismatic Octacyanometalates

TL;DR

This study demonstrates that blue light can induce and red light can reverse magnetization in a specific copper molybdenum cyanide compound, revealing a photoreversible magnetic behavior with electronic states that do not simply revert during the process.

Contribution

The paper provides a theoretical model explaining photoinduced reversible magnetism in a square-antiprismatic octacyanometalate, highlighting the electronic changes during magnetic switching.

Findings

Blue light induces magnetization in ${ m Cu}_2{ m Mo}({ m CN})_8ullet 8{ m H}_2{ m O}$

Red light demagnetizes the same material, completing a magnetic cycle

Electronic states do not simply revert during the magnetic switching process

Abstract

Irradiating ${\rm Cu}_2{\rm Mo}({\rm CN})_8\cdot 8{\rm H}_2{\rm O}$ with blue light induces a global magnetization, whereas succeeding irradiations with red or longer-wavelength light demagnetize this material. We solve the time-dependent Schr\"odinger equation for an extended Hubbard model to reproduce the photoreversible magnetism. Monitoring the photoinduced optical-conductivity and angle-resolved-photoemission spectra, we reveal that the magnetic round trip by way of ferromagnetism is far from a return in terms of electronics. While visible-light-induced magnetization has never been observed in the tungsten analog ${\rm Cu}_2{\rm W}({\rm CN})_8\cdot 5{\rm H}_2{\rm O}$, infrared-light irradiation may magnetize this material as well.