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Sixfold fermion near the Fermi level in cubic PtBi2
by S. Thirupathaiah, Y. S. Kushnirenk, K. Koepernik, B. R. Piening, B. Buechner, S. Aswartham, J. van den Brink, S. V. Borisenko, I. C. Fulga
|As Contributors:||Ion Cosma Fulga · Jeroen van den Brink|
|Arxiv Link:||https://arxiv.org/abs/2006.08642v1 (pdf)|
|Date submitted:||2020-06-17 02:00|
|Submitted by:||Fulga, Ion Cosma|
|Submitted to:||SciPost Physics|
|Subject area:||Condensed Matter Physics - Experiment|
We show that the cubic compound PtBi2, is a topological semimetal hosting a sixfold band touching point in close proximity to the Fermi level. Using angle-resolved photoemission spectroscopy, we map the bandstructure of the system, which is in good agreement with results from density functional theory. Further, by employing a low energy effective Hamiltonian valid close to the crossing point, we study the effect of a magnetic field on the sixfold fermion. The latter splits into a total of twenty Weyl cones for a Zeeman field oriented in the diagonal,  direction. Our results mark cubic PtBi2, as an ideal candidate to study the transport properties of gapless topological systems beyond Dirac and Weyl semimetals.
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Anonymous Report 2 on 2020-9-4 Invited Report
The authors report the experimental realization of a high order nodal point semimetal PtBi2. The experimental data and theory calculations are solid, and it deserves publication. I have a couple of objections that should be addressed.
1. Could the author use arrows also in Fig. (2) to be able to follow the explanation of the text ?
2. They claim under a Zeeman field the bands split in 20 Weyl points. They should explain why they are all Weyl nodes.
Anonymous Report 1 on 2020-7-24 Invited Report
Authors study electronic properties of PtBi2 using DFT calculations. They find that this material has sixfold band touching (sixfold fermion). The manuscript is well written and clearly argues the theoretical and experimental case. The only room for improvement would be figures:
1) I would suggest to use different color scheme for calculations and experimental data.
2) The FS data in Fig. 2 is plotted over many Brillouin zones (BZ) which makes it very unclear. If authors want to show multi zone plot I would suggest using just a single panel, then plotting only single BZ for each photon energy, so reader can see better the differences.
3) Fig 3 and 4 are key to the claims of the paper. The crosses obscure the data and it is not clear that the bands form the Dirac points, let alone six fold ones.
Perhaps adding a panel or figure that shows more clearly the Dirac points and all bands could resolve the issue. The authors could also try second derrivative technique to better visualize the bands.