1Department of Physics, Renmin University of China, Beijing 100872, China 2Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China 3Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 4CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China 5Songshan Lake Materials Laboratory, Dongguan 523808, China
Abstract：We report the magnetoresistance (MR), de Haas-van Alphen (dHvA) oscillations and the electronic structures of single-crystal PtGa. The large unsaturated MR is observed with the magnetic field $B \parallel [111]$. Evident dHvA oscillations with the $B \parallel [001]$ configuration are observed, from which twelve fundamental frequencies are extracted and the spin-orbit coupling (SOC) induced band splitting is revealed. The light cyclotron effective masses are extracted from the fitting by the thermal damping term of the Lifshitz–Kosevich formula. Combining with the calculated frequencies from the first-principles calculations, the dHvA frequencies $F_1/F_3$ and $F_{11}/F_{12}$ are confirmed to originate from the electron pockets at $\mit\Gamma$ and $R$, respectively. The first-principles calculations also reveal the existence of spin-3/2 Rarita–Schwinger–Weyl fermions and time-reversal doubling of the spin-1 excitation at $\mit\Gamma$ and $R$ with large Chern numbers of $\pm4$ when SOC is included.
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2020, Vol. 37 
