Fig. 1: de Haas-van Alphen (dHvA) effect.
a de Haas-van Alphen (dHvA) oscillations as a function of inverse field plotted at four representative temperatures. Data were collected from a NbGe2 crystal mounted on a piezoresistive cantilever. b The fast Fourier transform (FFT) of dHvA data. The inset shows a Lishitz-Kosevich fit to determine the effective mass at F = 2358 T. c Calculated Fermi surface of NbGe2. The top left and top right are two representative bands of NbGe2 shown in the first Brillouin zone and repeated zone scheme, respectively. One has a Fermi surface at the center while the other one is hollow. The center shows the side-view of the top left Fermi surface. The bottom Fermi surface is another band similar to the top-left one. The Fermi surface of NbGe2 comprises 4 bands in total, two are like top-left and the other two are like the top-right. The blue and magenta traces are cyclotron orbits as large as 2500 T and as small as 200 T, consistent with observed frequencies. d The experimental and theoretical quasiparticle masses plotted as a function of dHvA frequencies showing a three-fold enhancement in the experimental masses. The open data point is reproduced from ref. 37. The orange and green shaded areas highlight two standard deviations in the experimental and theoretical m* values, respectively.
