Terahertz electric-field-driven dynamical multiferroicity in SrTiO3

• 成果类型: Article
• 署名作者: Basini, M.; Pancaldi, M.; Wehinger, B.; Udina, M.; Unikandanunni, V.; Tadano, T.; Hoffmann, M. C.; Balatsky, A. V.; Bonetti, S.
• 署名单位: Stockholm University; Universita Ca Foscari Venezia; Elettra Sincrotrone Trieste; European Synchrotron Radiation Facility (ESRF); Sapienza University Rome; National Institute for Materials Science; Stanford University; United States Department of Energy (DOE); SLAC National Accelerator Laboratory; Nordic Institute for Theoretical Physics; University of Connecticut
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5374
• DOI: 10.1038/s41586-024-07175-9
• 发表日期: 2024-04-18
• 关键词: ferroelectricity; dependence; TRANSITION; phonon

摘要

The emergence of collective order in matter is among the most fundamental and intriguing phenomena in physics. In recent years, the dynamical control and creation of novel ordered states of matter not accessible in thermodynamic equilibrium is receiving much attention(1-6). The theoretical concept of dynamical multiferroicity has been introduced to describe the emergence of magnetization due to time-dependent electric polarization in non-ferromagnetic materials(7,8). In simple terms, the coherent rotating motion of the ions in a crystal induces a magnetic moment along the axis of rotation. Here we provide experimental evidence of room-temperature magnetization in the archetypal paraelectric perovskite SrTiO3 due to this mechanism. We resonantly drive the infrared-active soft phonon mode with an intense circularly polarized terahertz electric field and detect the time-resolved magneto-optical Kerr effect. A simple model, which includes two coupled nonlinear oscillators whose forces and couplings are derived with ab initio calculations using self-consistent phonon theory at a finite temperature(9), reproduces qualitatively our experimental observations. A quantitatively correct magnitude was obtained for the effect by also considering the phonon analogue of the reciprocal of the Einstein-de Haas effect, which is also called the Barnett effect, in which the total angular momentum from the phonon order is transferred to the electronic one. Our findings show a new path for the control of magnetism, for example, for ultrafast magnetic switches, by coherently controlling the lattice vibrations with light.