Abstract
In low–electron density materials, interactions can lead to highly correlated quantum states of matter. Ta2NiSe5, an excitonic insulator (EI) candidate, exists in a novel broken-symmetry phase below 327 K, characterized by robust exchange interaction and electron-lattice coupling. We study this phase of Ta2NiSe5 using the quadrupole circular photogalvanic effect (QCPGE). Light-matter interaction in Ta2NiSe5 mediated by electric quadrupole/magnetic dipole coupling produces helicity-dependent DC response even with centrosymmetry, making it particularly sensitive to certain other broken symmetries. We show that the exchange interaction in Ta2NiSe5 can lead to a triclinic structure with a broken C2 symmetry. Our results provide an incisive probe of the symmetries of the low-temperature phase of Ta2NiSe5 and add new symmetry constraints to the identification of a strongly correlated EI phase. The high sensitivity of QCPGE to subtle symmetry breaking in centrosymmetric systems will enable its use in studying other complex crystalline systems.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
