AI 中文总结
该研究发现洁净多带金属中存在一类新的大磁阻材料，其磁阻遵循单参数标度，揭示了无序、迁移率与对称性的相互作用。
AI 中文摘要
我们系统研究了单晶非磁性层状钯基金属的磁阻比（MR），包括中心对称的PdTe₂、PdPb₂和β-PdBi₂，以及非中心对称的α-PdBi。本研究在多带、高载流子密度体系中发现了一类独特的大MR。与研究较多的、由简单补偿载流子模型描述的狄拉克和外尔半金属等极大MR材料不同，这些化合物具有复杂的费米面，我们的第一性原理计算证实了这一点。不过，它们表现出由载流子迁移率决定的极其简单的MR标度，体现为对磁场、温度和剩余电阻率比（RRR）的系统依赖关系。高RRR晶体中科勒规则（Kohler's rule）的有效性表明，即使在这些多带体系中，MR也由单一有效散射时间决定。MR的磁场和RRR依赖关系遵循介于线性和二次之间的中间幂律行为，这可归因于不完善的载流子补偿和载流子迁移率的分布。在所研究的化合物中，α-PdBi的MR最大，达到1500%（2 K，7 T），这归因于其极高的RRR（约660）。然而，在相同RRR基础上比较时，其MR小于中心对称对应物。这一趋势表明，非中心对称体系中由自旋轨道诱导的能带分裂产生的额外散射通道降低了有效载流子迁移率。我们的结果在洁净多带金属中确立了一类新的大MR，其中复杂电子结构产生了涌现的单参数标度，突出了无序、迁移率和对称性之间的相互作用。
英文摘要
We systematically investigated the magnetoresistance ratio (MR) of single-crystalline, nonmagnetic layered Pd-based metals, including centrosymmetric PdTe2, PdPb2, and beta-PdBi2 and noncentrosymmetric alpha-PdBi. Our study identifies a distinct class of large MR in multiband, high-carrier-density systems. Unlike well-studied extremely large MR materials, such as Dirac and Weyl semimetals described by simple compensated-carrier models, these compounds possess complex Fermi surfaces, as validated by our first-principles calculations. Nevertheless, they exhibit a remarkably simple MR scaling governed by carrier mobility, manifested in systematic dependencies on magnetic field, temperature, and the residual resistivity ratio (RRR). The validity of Kohler's rule in high-RRR crystals indicates that MR is governed by a single effective scattering time, even in these multiband systems. The field and RRR dependences of MR follow an intermediate power-law behavior between linear and quadratic, attributable to imperfect carrier compensation and a distribution of carrier mobilities. Among the studied compounds, alpha-PdBi exhibits the largest MR, reaching 1500% (2 K, 7 T), owing to its exceptionally high RRR (approximately 660). However, when compared on an equal-RRR basis, its MR is smaller than that of its centrosymmetric counterparts. This trend suggests that additional scattering channels arising from spin-orbit-induced band splitting in noncentrosymmetric systems reduce the effective carrier mobility. Our results establish a new class of large MR in clean multiband metals where complex electronic structures give rise to emergent single-parameter scaling, highlighting the interplay between disorder, mobility, and symmetry.
Comments11 pages, 5 figures
