6 research outputs found
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Disorder-induced coupling of Weyl nodes in WTe2
The finite coupling between Weyl nodes due to residual disorder is investigated by magnetotransport studies in WTe2. The anisotropic scattering of quasiparticles is evidenced from classical and quantum transport measurements. A theoretical approach using the real band structure is developed in order to calculate the dependence of the scattering anisotropy with the correlation length of the disorder. A comparison between theory and experiments reveals a short correlation length in WTe2 (ξ∼5 nm). This result implies a significant coupling between Weyl nodes and other bands. Our study thus shows that a finite intercone scattering rate always exists in weakly disordered type-II Weyl semimetals, such as WTe2, which strongly suppresses topologically nontrivial properties
Bereziskii-Kosterlitz-Thouless transition in the Weyl system \ce{PtBi2}
Symmetry breaking in topological matter became, in the last decade, a key
concept in condensed matter physics to unveil novel electronic states. In this
work, we reveal that broken inversion symmetry and strong spin-orbit coupling
in trigonal \ce{PtBi2} lead to a Weyl semimetal band structure, with unusually
robust two-dimensional superconductivity in thin fims. Transport measurements
show that high-quality \ce{PtBi2} crystals are three-dimensional
superconductors (600~mK) with an isotropic critical field
(50~mT). Remarkably, we evidence in a rather thick flake
(60~nm), exfoliated from a macroscopic crystal, the two-dimensional nature of
the superconducting state, with a critical temperature ~mK and highly-anisotropic critical fields. Our results reveal a
Berezinskii-Kosterlitz-Thouless transition with ~mK and
with a broadening of Tc due to inhomogenities in the sample. Due to the very
long superconducting coherence length in \ce{PtBi2}, the
vortex-antivortex pairing mechanism can be studied in unusually-thick samples
(at least five times thicker than for any other two-dimensional
superconductor), making \ce{PtBi2} an ideal platform to study low dimensional
superconductivity in a topological semimetal
Diffusion inter-cônes des fermions de Weyl induite par le désordre dans WTe
International audienceThe finite coupling between Weyl nodes due to residual disorder is investigated by magnetotransport studies in WTe. The anisotropic scattering of quasiparticles is evidenced from classical and quantum transport measurements. A new theoretical approach using a real band structure is developed to calculate the dependence of the scattering anisotropy with the correlation length of the disorder. A comparison between theory and experiments reveals for the first time a short correlation length in WTe (~5nm). This result implies a significant coupling between Weyl nodes and other bands, so that inter-node scattering strongly reduces topologically non-trivial properties, such as the chiral anomaly.Le couplage résiduel entre deux cônes de Weyl de chiralité opposée, dû au désordre, est étudié par des mesures de magnéto-transport dans des films minces WTe. La diffusion anisotrope des quasi-particules est mise en évidence par une comparaison entre le libre parcours moyen élastique et la longueur de transport. Un modèle basé sur la structure de bande précise de WTe2 permet de déterminer la longueur de corrélation du désordre, à partir de la mesure expérimentale de l'anisotropie de diffusion. Cette valeur, très courte (~5nm), suggère un fort couplage entre paires de cônes de Weyl, ce qui devrait fortement réduire l'amplitude de propriétés topologiques, telle que l'anomalie chirale
Transition Bereziskii-Kosterlitz-Thouless dans des nanostructures du semimétal de Weyl \ce{PtBi2}
Symmetry breaking in topological matter became, in the last decade, a key concept in condensed matter physics to unveil novel electronic states. In this work, we reveal that broken inversion symmetry and strong spin-orbit coupling in trigonal \ce{PtBi2} lead to a Weyl semimetal band structure, with unusually robust two-dimensional superconductivity in thin fims. Transport measurements show that high-quality \ce{PtBi2} crystals are three-dimensional superconductors (600~mK) with an isotropic critical field (50~mT). Remarkably, we evidence in a rather thick flake (60~nm), exfoliated from a macroscopic crystal, the two-dimensional nature of the superconducting state, with a critical temperature ~mK and highly-anisotropic critical fields. Our results reveal a Berezinskii-Kosterlitz-Thouless transition with ~mK and with a broadening of Tc due to inhomogenities in the sample. Due to the very long superconducting coherence length in \ce{PtBi2}, the vortex-antivortex pairing mechanism can be studied in unusually-thick samples (at least five times thicker than for any other two-dimensional superconductor), making \ce{PtBi2} an ideal platform to study low dimensional superconductivity in a topological semimetal
Transition Bereziskii-Kosterlitz-Thouless dans des nanostructures du semimétal de Weyl \ce{PtBi2}
Symmetry breaking in topological matter became, in the last decade, a key concept in condensed matter physics to unveil novel electronic states. In this work, we reveal that broken inversion symmetry and strong spin-orbit coupling in trigonal \ce{PtBi2} lead to a Weyl semimetal band structure, with unusually robust two-dimensional superconductivity in thin fims. Transport measurements show that high-quality \ce{PtBi2} crystals are three-dimensional superconductors (600~mK) with an isotropic critical field (50~mT). Remarkably, we evidence in a rather thick flake (60~nm), exfoliated from a macroscopic crystal, the two-dimensional nature of the superconducting state, with a critical temperature ~mK and highly-anisotropic critical fields. Our results reveal a Berezinskii-Kosterlitz-Thouless transition with ~mK and with a broadening of Tc due to inhomogenities in the sample. Due to the very long superconducting coherence length in \ce{PtBi2}, the vortex-antivortex pairing mechanism can be studied in unusually-thick samples (at least five times thicker than for any other two-dimensional superconductor), making \ce{PtBi2} an ideal platform to study low dimensional superconductivity in a topological semimetal
Berezinskii–Kosterlitz–Thouless Transition in the Type‑I Weyl Semimetal PtBi<sub>2</sub>
Symmetry breaking in topological matter has become in
recent years
a key concept in condensed matter physics to unveil novel electronic
states. In this work, we predict that broken inversion symmetry and
strong spin–orbit coupling in trigonal PtBi2 lead
to a type-I Weyl semimetal band structure. Transport measurements
show an unusually robust low dimensional superconductivity in thin
exfoliated flakes up to 126 nm in thickness (with Tc ∼ 275–400 mK), which constitutes the first
report and study of unambiguous superconductivity in a type-I Weyl
semimetal. Remarkably, a Berezinskii-Kosterlitz-Thouless transition
with TBKT ∼ 310 mK is revealed
in up to 60 nm thick flakes, which is nearly an order of magnitude
thicker than the rare examples of two-dimensional superconductors
exhibiting such a transition. This makes PtBi2 an ideal
platform to study low dimensional and unconventional superconductivity
in topological semimetals