First Observation of the de Haas–van Alphen Effect and Fermi Surfaces in the Unconventional Superconductor UTe2 Article Swipe
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· 2022
· Open Access
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· DOI: https://doi.org/10.7566/jpsj.91.083704
· OA: W4281632517
We report the first observation of the de Haas-van Alphen (dHvA) effect in\nthe novel spin-triplet superconductor UTe2 using high quality single crystals\nwith the high residual resistivity ratio (RRR) over 200. The dHvA frequencies,\nnamed alpha and beta, are detected for the field directions between c and\na-axes. The frequency of branch beta increases rapidly with the field angle\ntilted from c to a-axis, while branch alpha splits, owing to the maximal and\nminimal cross-sectional areas from the same Fermi surface. Both dHvA branches,\nalpha and beta reveal two kinds of cylindrical Fermi surfaces with a strong\ncorrugation at least for branch alpha. The angular dependence of the dHvA\nfrequencies is in very good agreement with that calculated by the generalized\ngradient approximation (GGA) method taking into account the on-site Coulomb\nrepulsion of U = 2 eV, indicating the main Fermi surfaces are experimentally\ndetected. The detected cyclotron effective masses are large in the range from\n32 to 57 m0 . They are approximately 10-20 times lager than the corresponding\nband masses, consistent with the mass enhancement obtained from the Sommerfeld\ncoefficient and the calculated density of states at the Fermi level. The local\ndensity approximation (LDA) calculations of ThTe2 assuming U4+ with the 5f^2\nlocalized model are in less agreement with our experimental results, in spite\nof the prediction for two cylindrical Fermi surfaces, suggesting a mixed\nvalence states of U4+ and U3+ in UTe2.\n
