Experimental Observation of Dirac Nodal Links in Centrosymmetric Semimetal TiB2

Liu, Zhonghao and Lou, Rui and Guo, Pengjie and Wang, Qi and Sun, Shanshan and Li, Chenghe and Thirupathaiah, Setti and Fedorov, Alexander and Shen, Dawei and Liu, Kai and Lei, Hechang and Wang, Shancai (2018) Experimental Observation of Dirac Nodal Links in Centrosymmetric Semimetal TiB2. In: PHYSICAL REVIEW X, 8 (3).

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Abstract

The topological nodal-line semimetal state, serving as a fertile ground for various topological quantum phases, where a topological insulator, Dirac semimetal, or Weyl semimetal can be realized when the certain protecting symmetry is broken, has only been experimentally studied in very few materials. In contrast to discrete nodes, nodal lines with rich topological configurations can lead to more unusual transport phenomena. Utilizing angle-resolved photoemission spectroscopy and first-principles calculations, here, we provide compelling evidence of nodal-line fermions in centrosymmetric semimetal TiB2 with a negligible spin-orbit coupling effect. With the band crossings just below the Fermi energy, two groups of Dirac nodal rings are clearly observed without any interference from other bands, one surrounding the Brillouin zone (BZ) corner in the horizontal mirror plane sigma(h) and the other surrounding the BZ center in the vertical mirror plane sigma(v). The linear dispersions forming Dirac nodal rings are as wide as 2 eV. We further observe that the two groups of nodal rings link together along the G-K direction, composing a nodal-link configuration. The simple electronic structure with Dirac nodal links mainly constituting the Fermi surfaces suggests TiB2 as a remarkable platform for studying and applying the novel physical properties related to nodal-line fermions.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW X
Publisher:	AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Additional Information:	Copy right for this article belong to AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	06 Sep 2018 15:43
Last Modified:	06 Sep 2018 15:43
URI:	http://eprints.iisc.ac.in/id/eprint/60583

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