Large nonlinear optical magnetoelectric response in a noncentrosymmetric magnetic Weyl semimetal

• 成果类型: Article
• 署名作者: Shoriki, Kentaro; Moriishi, Keigo; Okamura, Yoshihiro; Yokoi, Kohei; Usui, Hidetomo; Murakawa, Hiroshi; Sakai, Hideaki; Hanasaki, Noriaki; Tokura, Yoshinori; Takahashi, Youtarou
• 署名单位: University of Tokyo; University of Tokyo; Gakushuin University; Shimane University; University of Osaka; RIKEN; University of Tokyo
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11185
• DOI: 10.1073/pnas.2316910121
• 发表日期: 2024-03-19
• 关键词: 2nd-harmonic generation

摘要

Weyl semimetals resulting from either inversion (P) or time- reversal (T) symmetry breaking have been revealed to show the record- breaking large optical response due to intense Berry curvature of Weyl-node pairs. Different classes of Weyl semimetals with both P and T symmetry breaking potentially exhibit optical magnetoelectric (ME) responses, which are essentially distinct from the previously observed optical responses in conventional Weyl semimetals, leading to the versatile functions such as directional dependence for light propagation and gyrotropic effects. However, such optical ME phenomena of (semi)metallic systems have remained elusive so far. Here, we show the large nonlinear optical ME response in noncentrosymmetric magnetic Weyl semimetal PrAlGe, in which the polar structural asymmetry and ferromagnetic ordering break P and T symmetry. We observe the giant second harmonic generation (SHG) arising from the P symmetry breaking in the paramagnetic phase, being comparable to the largest SHG response reported in Weyl semimetal TaAs. In the ferromagnetically ordered phase, it is found that interference between this nonmagnetic SHG and the magnetically induced SHG emerging due to both P and Tsymmetry breaking results in the magnetic field switching of SHG intensity. Furthermore, such an interference effect critically depends on the light- propagating direction. The corresponding magnetically induced nonlinear susceptibility is significantly larger than the prototypical ME material, manifesting the existence of the strong nonlinear dynamical ME coupling. The present findings establish the unique optical functionality of P- and T- symmetry broken ME topological semimetals.