Shubnikov-de Haas Oscillations in 2D $\text{PtSe}_2$: A fermiological Charge Carrier Investigation

TL;DR

This study uses high-field, low-temperature magnetotransport to reveal the fermiology of PtSe$_2$, showing Shubnikov–de Haas oscillations with a single dominant, planar electron pocket whose area and Berry phase reveal 2D confinement and non-trivial topology. The oscillations yield robust estimates of the cyclotron mass $m_c\approx0.32\,m_0$, quantum lifetime $\tau\sim(0.22{\pm}0.02)\times10^{-12}\,\mathrm{s}$, Dingle temperature $x\sim4\ \mathrm{K}$, and Berry phase $\Phi_B\approx\pi$, with the oscillation frequency $\mathfrak{F}$ diminishing as thickness decreases and bulk behavior recovered for $t>20\,\mathrm{nm}$. Angular dependence confirms 2D character, and a cyclotron radius $r_c\approx72\,\mathrm{nm}$ supports confinement within the few- to tens-of-nanometer regime. Weak antilocalization coexists with a Pt-vacancy–driven Kondo effect, indicating competing spin-orbit and magnetic scattering mechanisms, with 2D WAL fits capturing the features in 2-terminal and 4-terminal geometries. Overall, the results establish PtSe$_2$ as a promising platform for orbitronic and orbital Hall-based device architectures, where thickness control tunes the Fermi surface and related transport phenomena.

Abstract

High magnetic field and low temperature transport is carried out in order to characterize the charge carriers of $\text{PtSe}_2$. In particular, the Shubnikov-de Haas oscillations arising at applied magnetic field strengths $\gtrsim 4.5\,\text{T}$ are found to occur exclusively in plane and emerge at a layer thickness of $\approx 18\,\text{nm}$, increasing in amplitude and decreasing in frequency for thinner $\text{PtSe}_2$ flakes. Moreover, the quantum transport time, Berry phase, Dingle temperature and cyclotron mass of the charge carriers are ascertained. The emergence of weak antilocalization (WAL) lies in contrast to the presence of magnetic moments from Pt vacancies. An explanation is provided on how WAL and the Kondo effect can be observed within the same material. Detailed information about the charge carriers and transport phenomena in $\text{PtSe}_2$ is obtained, which is relevant for the design of prospective spintronic and orbitronic devices and for the realization of orbital Hall effect-based architectures.

Figures (30)

• Figure 1: a) Optical image of sample X1. b) Schematic of the Hall bar with the direction of the current density $\boldsymbol{j}$. Measuring the voltage difference between two terminals which lie on line parallel to $\boldsymbol{j}$, results in $\rho_{xx}$ while the voltage difference between terminals, which lies on a line normal to $\boldsymbol{j}$, yields $\rho_{xy}$.
• Figure 2: Upper panel: longitudinal 4-terminal resistance $\rho_{xx}-\rho_{xx}^{(\text{lin.})}$ of sample F over applied magnetic field for $\mu_0 H\geq 4.5\,\text{T}$ at $2\,\text{K}$. Inset: increased range of $|\mu_0H|\leq 6.8\,\text{T}$. Lower panel: equivalent plot for $\rho_{xy}$.
• Figure 3: $\widetilde{\rho_d}$ over applied magnetic field for sample F at $2\,\text{K}$. Solid curves: fits. The obtained values are given in Table \ref{['tab_LK_parameters']}
• Figure 4: Upper panel: $\widetilde{\sigma_{xx}}$ of sample F at $2\,\text{K}$ over inverse applied magnetic field magnitude and extracted peak center positions marked as squares/circles. Lower panel: Landau-fan diagram showing the indices over the peak positions from the upper panel and a linear fit. Insets: magnification of the identified peak positions and of the axis cutoff region. The obtained parameters are provided in Table S1 of the Supplemental Material Supplemental.
• Figure 5: Left panel: amplitude $\mathcal{A}$ resulting from the spectra of $\widetilde{\rho_{xy}}$ over frequency $\mathfrak{F}$ for specific flake thicknesses. The dotted circles are a guide to the eye. Right panel: $\widetilde{\rho_{xy}}$ as a function of applied magnetic field for specific flake thicknesses.