LaCu$_{x}$Sb$_{2}$的电子与磁性质随Cu占位调控
Electronic and magnetic properties of LaCu$_{x}$Sb$_{2}$ tuned by Cu occupancy
AI总结：
本文通过调控Cu占位$x$系统研究了LaCu$_{x}$Sb$_{2}$的电子和磁性质，结合量子振荡测量与DFT计算，揭示了其物理性质随$x$变化及费米面演化与Sb方网电子能带的关联。
摘要：
我们报道了LaCu$_{x}$Sb$_{2}$（$0.92 \leq x \leq 1.12$）的热力学和输运性质，该体系通过控制初始配料组成合成，并利用磁化、电阻率和比热测量进行研究。该体系的物理性质高度依赖于Cu位占位$x$，其中剩余电阻率比（RRR）、磁阻（MR）、超导转变温度（$T_{c}$）和电子比热系数（$γ$）均表现出随$x$的系统性变化。在接近Cu化学计量比$x \sim 1$的样品中，磁阻测量观察到Shubnikov-de Haas量子振荡，而de Haas-van Alphen振荡则在较宽的$x$范围（$0.92 \leq x \le 1.12$）内被探测到。对于$H \parallel c$，振荡频率表现出明显的$x$依赖性，表明费米面发生系统性变化。对最接近理想Cu化学计量比的样品进行的DFT计算揭示了具有方网基半金属共同特征的电子结构，与实验观测结果吻合良好。LaCu$_{x}$Sb$_{2}$对磁场的磁响应因费米面各向异性而呈各向异性。我们的结果表明物理性质如何受到Cu位占位$x$的影响，并与源自Sb方网的电子能带相关联。
英文摘要：
We report thermodynamic and transport properties of LaCu$_{x}$Sb$_{2}$ ($0.92 \leq x \leq 1.12$), synthesized by controlling the initial loading composition and investigated by magnetization, electrical resistivity, and specific heat measurements. The physical properties of this system are highly dependent on Cu-site occupancy $x$, where residual resistivity ratio (RRR), magnetoresistance (MR), superconducting transition temperature ($T_{c}$), and electronic specific heat coefficient ($γ$) indicate a systematic variation as a function of $x$. The Shubnikov-de Haas quantum oscillations are observed in magnetoresistance measurements for samples close to the Cu stoichiometry $x \sim 1$, while the de Haas-van Alphen oscillations are detected in a wide range of $x$ ($0.92 \leq x \le 1.12$). For $H \parallel c$, the oscillation frequency indicates a clear $x$-dependence, implying a systematic change of Fermi surface. DFT calculations for the sample closest to ideal Cu stoichiometry reveal electronic structures with a common feature of the square-net-based semimetals, which is in good agreement with the experimental observations. The magnetic response of LaCu$_{x}$Sb$_{2}$ to magnetic fields is anisotropic owing to the Fermi surface anisotropy. Our results show how the physical properties are influenced by the Cu-site occupancy $x$, linked to the electronic bands arising from the Sb square net.
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