Spontaneous gyrotropic electronic order in a transition-metal dichalcogenide

Su Yang Xu, Qiong Ma, Yang Gao, Anshul Kogar, Alfred Zong, Andrés M. Mier Valdivia, Thao H. Dinh, Shin Ming Huang, Bahadur Singh, Chuang Han Hsu, Tay Rong Chang, Jacob P.C. Ruff, Kenji Watanabe, Takashi Taniguchi, Hsin Lin, Goran Karapetrov, Di Xiao, Pablo Jarillo-Herrero, Nuh Gedik

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Chirality is ubiquitous in nature, and populations of opposite chiralities are surprisingly asymmetric at fundamental levels1,2. Examples range from parity violation in the subatomic weak force to homochirality in biomolecules. The ability to achieve chirality-selective synthesis (chiral induction) is of great importance in stereochemistry, molecular biology and pharmacology2. In condensed matter physics, a crystalline electronic system is geometrically chiral when it lacks mirror planes, space-inversion centres or rotoinversion axes1. Typically, geometrical chirality is predefined by the chiral lattice structure of a material, which is fixed on formation of the crystal. By contrast, in materials with gyrotropic order3–6, electrons spontaneously organize themselves to exhibit macroscopic chirality in an originally achiral lattice. Although such order—which has been proposed as the quantum analogue of cholesteric liquid crystals—has attracted considerable interest3–15, no clear observation or manipulation of gyrotropic order has been achieved so far. Here we report the realization of optical chiral induction and the observation of a gyrotropically ordered phase in the transition-metal dichalcogenide semimetal 1T-TiSe2. We show that shining mid-infrared circularly polarized light on 1T-TiSe2 while cooling it below the critical temperature leads to the preferential formation of one chiral domain. The chirality of this state is confirmed by the measurement of an out-of-plane circular photogalvanic current, the direction of which depends on the optical induction. Although the role of domain walls requires further investigation with local probes, the methodology demonstrated here can be applied to realize and control chiral electronic phases in other quantum materials4,16.

Original languageEnglish
Pages (from-to)545-549
Number of pages5
Issue number7796
Publication statusPublished - 2020 Feb 27

All Science Journal Classification (ASJC) codes

  • General


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