Observation of optically induced multiferroicity: Femtosecond laser pulse induces ultrafast transition to ferromagnetic ferroelectric state
Overview of the press release
Ferromagnetic (ferroelectric) materials have microscopic magnetic (electric) dipole moments, which are aligned in the same direction. These materials are widely applied to nonvolatile memories since the direction of magnetization (electric polarization) can be controlled by applying an external magnetic (electric) field. Recently, materials that simultaneously possess both magnetic and ferroelectric properties, known as multiferroics, have been attracting considerable attention because they exhibit a remarkable property called magnetoelectricity, which is an electric field that can manipulate the magnetic degree of freedom, and vice-versa. A significant amount of research has been devoted to exploiting this effect for magnetoelectric data storage and manipulation devices driven by direct current electric fields. Aiming at advancing the speed of magnetoelectric manipulation, a promising alternative approach offers similar control, relying on laser pulses to control both the charge and the magnetic order of solids.
In this study, researchers from the Graduate School of Science and the Graduate School of Frontier Science, The University of Tokyo, successfully induced a multiferroic state in a non-multiferroic material in less than one trillionth of a second (600 femtoseconds) by irradiating the material with ultrashort femtosecond laser pulses with a pulse duration of 100 fs. Observations of non-reciprocal directional dichroism in the material, a property observed in multiferroics where the strength of optical absorption depends on the direction of light propagation, provided supportive evidence for laser-induced magnetoelectricity. The results pave the way to ultrafast control of electric or optical devices based on multiferroics, and are expected to be applicable to ultrafast memory and optical switching technologies.
Figure: Schematic diagram of optically induced multiferroicity. In the initial state, microscopic magnets in a non-multiferroic material are randomly oriented and electric displacement does not occur. By irradiating the material with ultrashort laser pulses, a multiferroic state, in which microscopic magnets or electric displacements are aligned simultaneously in a certain direction, is induced in the material in less than one trillionth of a second.
Journal Nature Physics Title Femtosecond activation of magnetoelectricity Authors Davide Bossini*, Kuniaki Konishi, Shingo Toyoda, Taka-hisa Arima, Junji Yumoto, Makoto Kuwata-Gonokami DOI 10.1038/s41567-017-0036-1 Paper link https://www.nature.com/articles/s41567-017-0036-1
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