Chiral topology: from discovery to recent developments

日時　2023年2月28日　（火）　13：30～14：40
場所　オンライン(Zoom形式)
講師　Kaustuv Manna
(Indian Institute of Technology Delhi)

The interplay between topology and various symmetry-breaking phases of matter has emerged as a key frontier in solid-state physics. This provides a fertile platform to realize the elusive concepts from particle physics in a condensed matter system. Their topologically protected unusual electronic behavior carries immense interest for future dissipationless spintronics to other applications. Here I shall discuss our recent discovery of topological chiral crystals [1,2]. This novel phase of matter carries many intrinsic ideal and near-ideal properties that emerge as a direct consequence of the structural chirality of the crystals. They harbour a broad range of equally exotic phenomena, such as new Fermionic excitations that cannot exist in particle physics, a quantized photoresponse to circular light, or signatures of the chiral anomaly in phonon dynamics etc. In the talk, I shall illustrate high-quality crystal growth procedures of various candidate chiral materials, corresponding magneto-transport and ARPES measurements, resulting our discovery of chiral fermions and corresponding optical characterizations [1-13]. We revealed that these new fermionic excitations possess with maximal Chern number nature can provide of ±4 [3,4]. Besides, the details of the surface states originated from the Weyl points can be tuned by controlling the corresponding crystal-handedness [3,5]. Our recent experiments reveal for the first time, a higher-fold bulk-boundary correspondence beyond the conventional Weyl and Dirac semimetal systems: a multi-gap topology where the chiral states exhibit an emergent ladder structure in energy-momentum space [13-14].

[1] Nature 567, 500-505 (2019)
[2] Nat. Phys. 15, 759–765 (2019)
[3] Science 369, 179-183 (2020)
[4] Nat. Commun. 11, 2033 (2020)
[5] Nat. Commun. 11, 3507 (2020)
[6] Sci. Adv. 6, eaba0509 (2020)
[7] Nat. Commun. 12, 154 (2021)
[8] Proc Natl Acad Sci. 117, 27104 (2020)
[9] Phys. Rev. Lett. 127, 157405 (2021)
[10] Nat. Commun. 12, 3994 (2021)
[11] Nat. Phys. 18, 813–818 (2022)
[12] Adv. Mater. 32, 1908518 (2020)
[13] Nat. Phys. (2023), Published on 02.02.2023
[14] Phys. Rev. Lett. 130, 066402 (2023)

問合せ先　出田真一郎（放射光科学研究センター）