Search

Two-dimensional (2D) materials have gained increasing prominence not only in fundamental research but also in daily applications. However, to fully harness their potential, it is crucial to optimize their properties with an external parameter and track the electronic structure simultaneously. Magnetotransport over a wide magnetic field range is a powerful method to probe the electronic structure and, for metallic 2D materials, quantum oscillations superimposed on the transport signals encode Fermi surface parameters. In this manuscript, we utilize biaxial strain as an external tuning parameter and investigate the effects of strain on the electronic properties of two quasi-2D superconductors, MoTe2 and RbV3Sb5, by measuring their magnetoresistance in pulsed magnetic fields up to 60 T. With a careful selection of insulating substrates, we demonstrate the possibility of both the compressive and tensile biaxial strains imposed on MoTe2 and RbV3Sb5, respectively. For both systems, the applied strain has led to superconducting critical temperature enhancement compared to their free-standing counterparts, proving the effectiveness of this biaxial strain method at cryogenic temperatures. Clear quantum oscillations in the magnetoresistance—the Shubnikov–de Haas (SdH) effect—are obtained in both samples. In strained MoTe2, the magnetoresistance exhibits a nearly quadratic dependence on the magnetic field and remains non-saturating even at the highest field, whereas in strained RbV3Sb5, two SdH frequencies showed a substantial enhancement in effective mass values, hinting at a possible enhancement of charge fluctuations. Our results demonstrate that combining biaxial strain and pulsed magnetic field paves the way for studying 2D materials under unprecedented conditions. [ABSTRACT FROM AUTHOR]

Materials with AV3Sb5 (A = K, Rb, Cs) stoichiometry are recently discovered kagome superconductors with the electronic structure featuring a Dirac band, van Hove singularities, and flat bands. These systems undergo anomalous charge-density-wave transitions at T CDW ∼ 80 – 100 K, resulting in the reconstruction of the Fermi surface from the pristine phase. Although comprehensive investigations of the electronic structure via quantum oscillations (QOs) have been performed on the sister compounds CsV3Sb5 and RbV3Sb5, a detailed QO study of KV3Sb5 is so far absent. Here, we report the Shubnikov–de Haas QO study in KV3Sb5. We resolve a large number of new frequencies with the highest frequency of 2202 T (occupying ∼54% of the Brillouin zone area in the kx–ky plane). The Lifshitz-Kosevich analysis further gives relatively small cyclotron effective masses, and the angular dependence study reveals the two-dimensional nature of the frequencies with a sufficient signal-to-noise ratio. Finally, we compare the QO spectra for all three AV3Sb5 compounds collected under the same conditions, enabling us to point out the similarities and the differences across these systems. Our results fill in the gap of the QO study in KV3Sb5 and provide valuable data to understand the band structure of all three members of AV3Sb5. [ABSTRACT FROM AUTHOR]