Abstract
Triply degenerate point (TP) fermions in tungsten–carbide-type materials (e.g., MoP), which represent new topological states of quantum matter, have generated immense interest recently. However, the TPs in these materials are found to be far below the Fermi level, leading to the TP fermions having less contribution to low-energy quasiparticle excitations. Here, we theoretically predict the existence of TP fermions with TP points close to the Fermi level in trigonal layered PtBi2 by ab initio calculations, and experimentally verify the predicted band topology by magnetotransport measurements under high magnetic fields up to 40 T. Analyses of both the pronounced Shubnikov–de Haas and de Haas–van Alphen oscillations reveal the existence of six principal Fermi pockets. Our experimental results, together with those from ab initio calculations, reveal the interplay between transport behaviors and unique electronic structures, and support the existence of TP fermions in trigonal layered PtBi2.
Highlights
Degenerate point (TP) fermions in tungsten–carbide-type materials (e.g., MoP), which represent new topological states of quantum matter, have generated immense interest recently
Triply degenerate point (TP) fermions have been predicted to exist in the electronic structure of a series of materials with tungsten–carbide (WC-) type crystal structure[20,21,22,23]
We theoretically predict that the trigonal layered PtBi2 hosts TP fermions that are close to the Fermi level
Summary
Degenerate point (TP) fermions in tungsten–carbide-type materials (e.g., MoP), which represent new topological states of quantum matter, have generated immense interest recently. We theoretically predict the existence of TP fermions with TP points close to the Fermi level in trigonal layered PtBi2 by ab initio calculations, and experimentally verify the predicted band topology by magnetotransport measurements under high magnetic fields up to 40 T. Analyses of both the pronounced Shubnikov–de Haas and de Haas–van Alphen oscillations reveal the existence of six principal Fermi pockets. Similar oscillations in magnetization are observed clearly due to the de Haas–van Alphen (dHvA) effect Analyses of both SdH and dHvA oscillations reveal the existence of six principal Fermi pockets, in which three present signatures of relativistic fermion behavior with light effective masses. Combining the results of ab initio calculations and theoretical analyses, we demonstrate that the exotic experimental results can be reasonably understood within the framework of unique electronic structures around the TPs
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