Quantum oscillations in the type-II Dirac semi-metal candidate PtSe₂

Abstract

Three-dimensional topological semi-metals carry quasiparticle states that mimic massless relativistic Dirac fermions, elusive particles that have never been observed in nature. As they appear in the solid body, they are not bound to the usual symmetries of space-time and thus new types of fermionic excitations that explicitly violate Lorentz-invariance have been proposed, the so-called type-II Dirac fermions. We investigate the electronic spectrum of the transition-metal dichalcogenide PtSe 2 by means of quantum oscillation measurements in fields up to 65 T. The observed Fermi surfaces agree well with the expectations from band structure calculations, that recently predicted a type-II Dirac node to occur in this material. A hole-and an electron-like Fermi surface dominate the semi-metal at the Fermi level. The quasiparticle mass is significantly enhanced over the bare band mass value, likely by phonon renormalization. Our work is consistent with the existence of type-II Dirac nodes in PtSe 2 , yet the Dirac node is too far below the Fermi level to support free Dirac-fermion excitations.

Edge‐Orientation Dependent Nanoimaging of Mid‐Infrared Waveguide Modes in High‐Index PtSe2

“…The second term is the Drude term which refers to intraband transition of the free charge carriers while the third term is associated with the effect of interband transitions of the bound charge carriers. Previous studies have found that the concentration and the effective mass of the free charge carriers of bulk PtSe 2 are N = 1.7 × 10 20 cm -3 [22] and m * = 2.5m e , [23] respectively, where m e is the electron rest mass. Using these values, the plasma frequency ( p…”

Dual quantum confinement and anisotropic spin splitting in the multivalley semimetal PtSe2

“…Here, we investigate a TMD, 1T -PtSe 2 , whose ground state is not a semiconductor, but a semimetal. It has a metallic temperature-dependent resistivity [28], and as such would not typically be considered as a natural system for electrical gating. We nonetheless show that an electrostatic band bending potential can be created to screen a surface (or equivalently gate-induced) charge, which in turn confines a well-defined 2DEG.…”

Asymmetric Fermi velocity induced chiral magnetotransport anisotropy in the type-II Dirac semi-metal PtSe2

“…The adjacent unoccupied Se layers are held together by weak van der Waals interactions. Theoretical calculations and ARPES show that the Fermi surface in PtSe 2 sits at >1 eV above the Dirac point 17,33 . The large ΔE hinders the detection of the chiral anomaly induced negative MR in the stoichiometric PtSe 2 .…”

“…As this material has been only recently explored, only a weak chiral negative MR of $À0:1% has been reported recently 32 . The in-depth transport measurements are still lacking 33 . As a transition metal dichalcogenide of 1T structural phase, PtSe 2 hosts a nonnegligible in-plane anisotropy, which may have an important role in its magnetotranport in addition to the chiral anomaly.…”