Seminars Archive

Exploring the Interplay of Shubnikov-de Haas Oscillations, Kondo Effect and Weak Antilocalization in the Dirac Semimetal PtSe2

Abstract
Transition-metal dichalcogenides exhibit a range of exploitable features, including the chiral magnetic effect (CME), orbital Hall effect (OHE) [1], type-II Dirac cones breaking the Lorentz invariance, and topologically non-trivial surface states [2]. Understanding the nature of the charge carriers and the electronic structure of the Dirac semimetal PtSe2, which offers both air-stability and significant spin-orbit coupling, is crucial for advancing experimental realizations of OHE-based devices and interpreting the role of the Dirac cones. A comprehensive low-temperature and high-magnetic-field magnetotransport study of PtSe2 flakes is presented, focusing on the Shubnikov-de Haas (SdH) oscillations, emerging as the applied magnetic field strengths exceeding 4.5 T [3]. These oscillations are found to occur exclusively in-plane and emerge up to a layer thickness of ~ 18 nm, with their amplitude increasing and frequency decreasing for thinner flakes, pointing at quantum oscillations from surface Fermi arcs [4].
The analysis employs a Lifshitz-Kosevich [5] formalism to extract key charge carrier characteristics, including quantum scattering time, cyclotron mass, and Berry phase. Furthermore, the resistance over temperature curves under zero-field-cooling and field-cooling establish a negative longitudinal magnetoresistance (NLMR). The interplay between weak anti-localization, Kondo effect, and orbital magnetoresistance is explored, revealing that the Kondo effect, stemming from Pt vacancies, is the source of the observed NLMR [6], in contrast to a previously reported CME [7]. Density functional theory supports the model, indicating that the concentration of Pt vacancies and sample thickness are critical tuning parameters for controlling the emergent two-dimensional spin density. The findings highlight the effect of the presence of Pt vacancies, together with the role played by quantum oscillation mechanics in Landau orbits. Significantly, they position PtSe2 as a platform for studying the OHE and provide crucial information on charge carriers, relevant for the design of prospective spintronic and orbitronic devices.

References

[1] P. Sahu et al., Phys. Rev. B 110, 054403 (2024)
[2] C. Yim, et al., NPJ 2D Mater. Appl. 2, 5 (2018)
[3] J. M. Salchegger et al., arxiv:2505.15666 (2025)
[4] A. Potter et al., Nat Commun 5, 5161 (2014)
[5] I. Lifshitz and A. Kosevich, JETP 2, 636 (1956)
[6] J. M. Salchegger et al., Phys. Rev. B 110, 205403 (2024)
[7] Z. Li et al., Phys. Rev. B 98(2), 165441 (2018)