Hagiwara Kenta, Chen Ying-Jiun, Go Dongwook, Tan Xin Liang, Grytsiuk Sergii, Yang Kui-Hon Ou, Shu Guo-Jiun, Chien Jing, Shen Yi-Hsin, Huang Xiang-Lin, Cojocariu Iulia, Feyer Vitaliy, Lin Minn-Tsong, Blügel Stefan, Schneider Claus Michael, Mokrousov Yuriy, Tusche Christian
Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany.
Faculty of Physics, University of Duisburg-Essen, 47057, Duisburg, Germany.
Adv Mater. 2025 Jul;37(27):e2418040. doi: 10.1002/adma.202418040. Epub 2025 May 2.
Chirality is ubiquitous in nature and manifests in a wide range of phenomena including chemical reactions, biological processes, and quantum transport of electrons. In quantum materials, the chirality of fermions, given by the relative directions between the electron spin and momentum, is connected to the band topology of electronic states. This study shows that in structurally chiral materials like CoSi, the orbital angular momentum (OAM) serves as the main driver of a nontrivial band topology in this new class of unconventional topological semimetals, even when spin-orbit coupling is negligible. A nontrivial orbital-momentum locking of multifold chiral fermions in the bulk leads to a pronounced OAM texture of the helicoid Fermi arcs at the surface. The study highlights the pivotal role of the orbital degree of freedom for the chirality and topology of electron states, in general, and paves the way towards the application of topological chiral semimetals in orbitronic devices.
手性在自然界中无处不在，并体现在广泛的现象中，包括化学反应、生物过程和电子的量子输运。在量子材料中，费米子的手性由电子自旋和动量之间的相对方向给出，它与电子态的能带拓扑结构相关。这项研究表明，在像CoSi这样的结构手性材料中，即使自旋轨道耦合可以忽略不计，轨道角动量（OAM）也是这类新型非常规拓扑半金属中非平凡能带拓扑结构的主要驱动力。体相中多重手性费米子的非平凡轨道动量锁定导致表面螺旋状费米弧出现明显的OAM纹理。该研究突出了轨道自由度对于电子态的手性和拓扑结构的关键作用，总体而言，为拓扑手性半金属在轨道电子学器件中的应用铺平了道路。
