Quasi-two-dimensional relativistic fermions probed by de Haas-van Alphen quantum oscillations in LuSn2

We report de Haas-van Alphen (dHvA) quantum oscillation studies on a layered compound LuSn2. Through the analyses of the dHvA oscillation data, we find this material has several 3D bands and one quasi-2D band hosting relativistic fermions. Compared to previously reported dHvA oscitations in YSn2, the oscillation component arising from the quasi-2D band is significantly enhanced. From structural analyses using single-crystal x-ray diffraction, we find the distorted Sn-square net layer is less corrugated than YSn2, which accounts for the enhancement of two dimensionality of the relativistic fermions created in this layer. This result suggests that the dimensionality of relativistic band in RESn2 (RE=rare earth) can be tuned by electronegativity of RE. Moreover, we also find the 3D relativistic bands are pushed closer to the Fermi level with respect to YSn2, due to enhanced spin-orbital coupling. These findings imply RESn2 can be an interesting platform for seeking new topological states via the tuning of electronegativity, spin-orbital coupling, and magnetism.