The emergent field of ‘straintronics’, taking advantage of elastic properties of materials, is aiming at realizing new low-power multi-stimuli devices. Researchers at IPCMS, in collaboration with CEA Paris, the Helmoltz Zentrum Berlin, Sheffield University and Freiberg Institute for Experimental Physics found a new method to write magnetic properties optically via the photo-ferro-elastic coupling. Light can polarize electrically the multiferroic BiFeO3 due to its photovoltaic property. This leads to the possibility to create multiple remanent polarization states by using different illumination times. Thanks to piezoelectricity these light induced polarization states of the ferroelectric are connected with its deformation. The later can be used to stress a superposed ferromagnetic Ni film in order to modify its magnetic anisotropy. As a proof-of-principle of this concept related to intertwined ferroic properties, a 75% change in coercivity in the Ni film is achieved via optical and nonvolatile control (Fig. 1a). Ferroelasticity makes possible to reverse this indirect photoferromagnetic effect by static or ac electric depolarization of the substrate. Hence, the strain dependent changes in magnetic properties are written optically, and erased electrically. Light-mediated straintronics can therefore be an alternative way for multi-functionality between spins, photons and electric charges where the photostriction was a missing property (Fig. 1b).
 V. Iurchuk, D. Schick, J. Bran, D. Colson, A. Forget, D. Halley, A. Koc, M. Reinhardt, C. Kwamen, N. A. Morley, M. Bargheer, M. Viret, R. Gumeniuk, G. Schmerber, B. Doudin, and B. Kundys Phys. Rev. Lett. 117, 107403 (2016).