AgNiO$_2$和AgNi$_{1-x}$Co$_{x}$O$_2$铜铁矿电子与光学性质的DFT+U与量子蒙特卡洛研究
DFT+U and Quantum Monte Carlo study of electronic and optical properties of AgNiO$_2$ and AgNi$_{1-x}$Co$_{x}$O$_2$ delafossite
AI总结：
本研究针对AgNiO$_2$基铜铁矿的强关联效应问题，采用量子蒙特卡洛模拟结合DFT对比，揭示了Co掺杂AgNi$_{1-x}$Co$_{x}$O$_2$中随浓度变化的金属-绝缘体转变与重入行为。
摘要：
作为唯一一种基于$d^{10}$的半金属铜铁矿，AgNiO$_2$因其独特的半金属性以及NiO$_2$层中与晶格畸变耦合的反铁磁性而受到广泛关注。相比之下，AgCoO$_2$等其他铜铁矿则是绝缘的。本文研究了AgNi$_{1-x}$Co$_{x}$O$_2$合金的电子结构如何随Ni/Co浓度变化，以探究这类金属间化合物的电子性质和相稳定性。尽管已有研究采用密度泛函理论（DFT）研究铜铁矿的电子和磁结构，但早期研究并未包含强在位库仑相互作用的修正。为准确处理这些相互作用，本研究使用量子蒙特卡洛（QMC）模拟来精确估算AgNiO$_2$的电子和磁性质。通过与DFT结果对比，我们表明这些电子关联效应是必须考虑的关键因素。研究发现，在磁性Ni位点进行Co掺杂会在$x\thicksim 0.33$附近引发金属-绝缘体转变，并在$x\thicksim 0.66$附近出现重入行为。
英文摘要：
As the only semimetallic $d^{10}$-based delafossite, AgNiO$_2$ has received a great deal of attention due to both its unique semimetallicity and its antiferromagnetism in the NiO$_2$ layer that is coupled with a lattice distortion. In contrast, other delafossites such as AgCoO$_2$ are insulating. Here we study how the electronic structure of AgNi$_{1-x}$Co$_{x}$O$_2$ alloys vary with Ni/Co concentration, in order to investigate the electronic properties and phase stability of the intermetallics. While the electronic and magnetic structure of delafossites have been studied using Density Functional Theory (DFT), earlier studies have not included corrections for strong on-site Coulomb interactions. In order to treat these interactions accurately, in this study we use Quantum Monte Carlo (QMC) simulations to obtain accurate estimates for the electronic and magnetic properties of AgNiO$_2$. By comparison to DFT results we show that these electron correlations are critical to account for. We show that Co doping on the magnetic Ni sites results in a metal-insulator transition near $x\sim 0.33$, and reentrant behavior near $x\sim 0.66$
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