Fermi surface topology and magnetotransport properties of superconducting Pd3Bi2Se2

Abstract

Pd3Bi2Se2 is a rare realization of a superconducting metal with a nonzero Z2 topological invariant. Here, we report the growth of high-quality single crystals of layered Pd3Bi2Se2 with a superconducting transition at Tc ≈ 0.80 K and upper critical fields of ∼10 and ∼5 mT for the in-plane and out-of-plane directions, respectively. Our density-functional theory (DFT) calculations reveal three pairs of doubly degenerate bands crossing the Fermi level, all displaying clear three-dimensional dispersion consistent with the overall low electronic anisotropy (<2). The multiband electronic nature of Pd3Bi2Se2 is evident in magnetotransport measurements, yielding a sign-changing Hall resistivity at low temperatures. The magnetoresistance is nonsaturating and follows Kohler's scaling rule. We interpret the magnetotransport data in terms of open orbits that are revealed in the DFT-calculated Fermi surface. de Haas–van Alphen (dHvA) oscillation measurements using torque magnetometry on single crystals yield four frequencies for out-of-plane fields: Fα=150±26T, Fβ=293±10T, Fγ=375±20T, and Fη=1017±12T, with the low frequency dominating the spectrum. Through the measurement of angular-dependent dHvA oscillations and DFT calculations we identify the Fα frequency with an approximately ellipsoidal electron pocket centered on the L2 point of the Brillouin zone. Lifshitz-Kosevich analysis of the dHvA oscillations reveals a small cyclotron effective mass m*=(0.11±0.02)m0 and a nontrivial Berry phase for the dominant orbit. The presence of nontrivial topology in a bulk superconductor positions Pd3Bi2Se2 as a potential candidate for exploring topological superconductivity.

Source-reported materials — not catalogue approval

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