Multiple mechanisms for extremely large magnetoresistance (XMR) found in many topologically nontrivial/trivial semimetals have been theoretically proposed, but experimentally it is unclear which mechanism is responsible in a particular sample. In this paper, by the combination of band structure calculations, numerical simulations of magnetoresistance (MR), Hall resistivity, and de Haas-van Alphen (dHvA) oscillation measurements, we studied the MR anisotropy of $\mathrm{Si}{\mathrm{P}}_2$ which is verified to be a topologically trivial, incomplete compensation semimetal. It was found that as magnetic field $H$ is applied along the $a$ axis, the MR exhibits an unsaturated nearly linear $H$ dependence, which was argued to arise from incomplete carriers compensation. For the $H\parallel \left[101\right]$ orientation, an unsaturated nearly quadratic $H$ dependence of MR up to $5.88\times {10}^4\%$ (at 1.8 K, 31.2 T) and field-induced up-turn behavior in resistivity were observed, which was suggested due to the existence of hole open orbits extending along the $k_x$ direction. Good agreement of the experimental results with the simulations based on the calculated Fermi surface (FS) indicates that the topology of FS plays an important role in its MR.

中文翻译：

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半金属SiP2中的线性和二次磁阻

在理论上已经提出了在许多拓扑非平凡/平凡的半金属中发现的极大磁阻（XMR）的多种机理，但在实验上尚不清楚哪种机理在特定样品中起作用。本文通过结合能带结构计算，磁阻（MR），霍尔电阻率和de Haas-van Alphen（dHvA）振荡测量的数值模拟，研究了Mr的各向异性。$硅{\mathrm{P}}_2$经验证是拓扑上琐碎的，不完全补偿的半金属。发现作为磁场 $H$ 沿 $\mathrm{一种}$ 轴，MR表现出不饱和的近似线性 $H$ 依赖，这被认为是由不完全的承运人补偿引起的。为了$H\parallel \left[101\right]$ 方向，不饱和的几乎二次的 $H$ MR的依赖性 $5.88\times {10}^4％$ （在1.8 K，31.2 T时），并观察到了电阻率引起的场上上升行为，这是由于存在沿空洞延伸的开孔轨道所致。 ${ķ}_X$方向。实验结果与基于计算的费米表面（FS）的仿真结果吻合良好，表明FS的拓扑结构在其MR中起着重要作用。