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X-WR-CALNAME:Laboratoire de physique des Solides
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DTSTART;TZID=Europe/Paris:20221003T140000
DTEND;TZID=Europe/Paris:20221003T180000
DTSTAMP:20220924T073500
UID:MEC-cac8e13055d2e4f62b6322254203b293@lps.u-psud.fr
CREATED:20220924
LAST-MODIFIED:20220924
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SUMMARY:Arthur Veyrat I Low dimensionality and Weyl topology in layered trigonal-PtBi2
DESCRIPTION:\nInstitute for Solid State Research, Leibniz Institute for Solid State and Materials Research,Dresden, Germany\n\n\n\nIn the last few years Weyl semimetals have attracted considerable attention as they are predictedto display new and exotic physics, for instance a new type of topological superconductivity.In this seminar, I will present a low temperature charge transport study of the newly predictedWeyl semimetal trigonal-PtBi2, focusing on two main results: the discoveries of superconductivityand planar Hall Effect in thin exfoliated flakes of t-PtBi2.While superconductivity has already been found under pressure in t-PtBi2 above 2K (1, 2),we found that single crystals of t-PtBi2 also display superconductivity at ambient pressure, with acritical temperature Tc ∼ 600mK (3). When thinning down the crystals using mechanical exfolia-tion, the superconductivity changes with the thickness, with a reduction of the critical temperaturedown to Tc ∼ 350mK. The superconductivity also becomes two-dimensional when reducing thethickness below arround t ∼ 60nm. Remarkably, even at such large thicknesses nanostructuresshow clear evidence of Berezinskii–Kosterlitz–Thouless (BKT) transitions, demonstrating the lowdimensionality of the superconductivity.At higher temperature (in the normal state), we found that the in-plane magnetoresistance ishighly dependent on the angle between the in-plane magnetic field and the current flowing in thesample, with a π-periodic dependence of both the longitudinal and transverse magnetoresistanceswhen rotating the field in the sample’s plane, and a π/4 phase offset between the two. This istypical of the so called planar Hall effect (PHE), which can be a signature of Weyl topology innon-magnetic materials (4, 5), and has been found to be a more accurate effect to experimentallyunveil Weyl physics in samples than the chiral anomaly, which can be hidden in materials with alarge orbital magnetoresistance (6).An additional 2π-periodic angular dependence is found in the transverse resistance, which mightbe a manifestation on a recently predicted anomalous planar Hall effect (APHE) (7 ), and shouldappear as a result of a non-vanishing Berry curvature in materials with broken C2 symmetry.References1. J. Wang et al., Physical Review B 103, Publisher: American Physical Society, 1–6, ISSN:24699969 (2021).2. D. L. Bashlakov et al., arXiv e-prints, arXiv: 2205.06610, (https://arxiv.org/abs/2205.06610v1) (May 2022).3. A. Veyrat et al., arXiv e-prints, arXiv: 2101.01620, (http://arxiv.org/abs/2101.01620)(Jan. 2021).4. A. A. Burkov, Physical Review B 96, 041110, ISSN: 2469-9950, (http://link.aps.org/doi/10.1103/PhysRevB.96.041110) (July 2017).5. S. Nandy, G. Sharma, A. Taraphder, S. Tewari, Physical Review Letters 119, 1–6, ISSN:10797114 (2017).6. P. Li et al., Physical Review B 100, Publisher: American Physical Society, 205128, ISSN:2469-9950, (https://link.aps.org/doi/10.1103/PhysRevB.100.205128) (Nov. 2019).7. R. Battilomo, N. Scopigno, C. Ortix, Physical Review Research 3, Publisher: American Phys-ical Society, 1–6, ISSN: 2643-1564 (2021).\n
URL:https://www.lps.u-psud.fr/events/arthur-veyrat-i-low-dimensionality-and-weyl-topology-in-layered-trigonal-ptbi2/
ORGANIZER;CN=APRILI:MAILTO:
CATEGORIES:Séminaire Matière Quantique (SMQ)
LOCATION:Moyen amphi (LPS
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