Femtosecond activation of magnetoelectricity

• Published in: Nature physics Vol. 14; no. 4; pp. 370 - 374
• Main Authors: Bossini, D., Konishi, K., Toyoda, S., Arima, T., Yumoto, J., Kuwata-Gonokami, M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2018; Nature Publishing Group
• Subjects: 140/125; 639/766/119; 639/766/119/996; Atomic; Brillouin zones; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Data storage; Electronic devices; Experiments; Letter; Light; Magnetic fields; Magnetism; Magnons; Mathematical and Computational Physics; Molecular; Multiferroic materials; Optical and Plasma Physics; Optical control; Phase transitions; Physics; Physics and Astronomy; Science; Theoretical; Time
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/s41567-017-0036-1

In magnetoelectric and multiferroic materials, the magnetic degree of freedom can be controlled by electric field, and vice versa. A significant amount of research has been devoted to exploiting this effect for magnetoelectric data storage and manipulation devices driven by d.c. electric fields 1 – 4 . Aiming at ever-faster schemes of magnetoelectric manipulation, a promising alternative approach offers similar control on a femtosecond timescale, relying on laser pulses 4 – 6 to control both the charge 7 , 8 and the magnetic 9 , 10 order of solids. Here we photo-induce magnetoelectricity and multiferroicity in CuB 2 O 4 on a sub-picosecond timescale. This process is triggered by the resonant optical generation of the highest-energy magnetic excitations—magnons with wavevectors near the edges of the Brillouin zone. The most striking consequence of the photo-excitation is that the absorption of light becomes non-reciprocal, which means that the material exhibits a different transparency for two opposite directions of propagation of light. The photo-induced magnetoelectricity does not show any decay on the picosecond timescale. Our findings uncover a path for ultrafast manipulations of the intrinsic coupling between charges and spins in multiferroics 4 , which may reveal unexplored magnetic configurations and unravel new functionalities in terms of femtosecond optical control of magnetism. Pump–probe measurements of CuB 2 O 4 reveal non-reciprocal directional dichroism, demonstrating the possibility to optically induce magnetoelectricity in a material on a femtosecond timescale.