Photo-induced chirality in a nonchiral crystal
Zhiyang Zeng, M. Först, M. Fechner, M. Buzzi, Emmanuel B. Amuah, Carsten Putzke, Philip J. W. Moll, D. Prabhakaran, P. G. Radaelli, A. Cavalleri
Abstract
Chirality, a pervasive form of symmetry, is intimately connected to the physical properties of solids, as well as the chemical and biological activity of molecular systems. However, inducing chirality in a nonchiral material is challenging because this requires that all mirrors and all roto-inversions be simultaneously broken. Here, we show that chirality of either handedness can be induced in the nonchiral piezoelectric material boron phosphate (BPO 4 ) by irradiation with terahertz pulses. Resonant excitation of either one of two orthogonal, degenerate vibrational modes determines the sign of the induced chiral order parameter. The optical activity of the photo-induced phases is comparable to the static value of prototypical chiral α-quartz. Our findings offer new prospects for the control of out-of-equilibrium quantum phenomena in complex materials.