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Condensed Matter > Materials Science
Title: Momentum-space signatures of Berry flux monopoles in a Weyl semimetal
(Submitted on 13 Dec 2020 (v1), last revised 21 Mar 2023 (this version, v2))
Abstract: Since the early days of Dirac flux quantization, magnetic monopoles have been sought after as a potential corollary of quantized electric charge. As opposed to magnetic monopoles embedded into the theory of electromagnetism, Weyl crystals exhibit Berry flux monopoles in reciprocal parameter space. As a function of crystal momentum, such monopoles locate at the degeneracy point of the Weyl cone. Here, we report momentum-resolved spectroscopic signatures of Berry flux monopoles in TaAs as a paradigmatic Weyl semimetal. We have probed the orbital and spin angular momentum (OAM and SAM) of the Weyl-fermion states by angle-resolved photoemission spectroscopy at bulk-sensitive soft X-ray energies (SX-ARPES) combined with photoelectron spin detection and circular dichroism. Supported by first-principles calculations, our measurements image characteristics of a topologically non-trivial winding of the OAM at the Weyl nodes and unveil a chirality-dependent SAM of the Weyl bands. Our results experimentally visualize the non-trivial momentum-space topology in a Weyl semimetal, promising to have profound implications for the study of quantum-geometric effects in solids.
Submission history
From: Hendrik Bentmann [view email][v1] Sun, 13 Dec 2020 08:02:32 GMT (3646kb,D)
[v2] Tue, 21 Mar 2023 10:30:37 GMT (3658kb,D)
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