论文标题
通过第一个原理计算和蒙特卡洛模拟对Nio和MNO进行深入研究
A deep investigation of NiO and MnO through the first principle calculations and Monte Carlo simulations
论文作者
论文摘要
在这项研究中，我们使用Hubbard校正的密度功能理论（DFT+$ U $）来得出由Heisenberg交换相互作用组成的旋转模型汉密尔顿人，直到第四个最近的邻居和双征相互作用。我们将DFT+$ u $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $，以估算海森伯格交流的海森伯格旋转模型。我们证明，磁性配置的数量应至少是正确估计交换参数的两倍的交换参数数量。为了计算两季度相互作用，我们提出了特定的非结合磁性构型，这些磁性不改变海森贝格自旋模型的能量。我们使用经典的蒙特卡洛（MC）模拟来评估DFT+$ u $结果。我们获得了磁敏感性和特定热量的温度依赖性，以确定库里·韦斯（Curie-Weiss）和内尔（Néel）温度。 MC模拟表明，尽管生物二极管相互作用无法改变Néel温度，但它会修改顺序参数。我们指出，要在经典的MC模拟和实验之间进行公平的比较，我们需要通过在经典MC模拟中应用$（S+1）/s $校正来考虑量子效应。
In this study, we use Hubbard-Corrected density functional theory (DFT+$U$) to derive spin model Hamiltonians consisting of Heisenberg exchange interactions up to the fourth nearest neighbors and bi-quadratic interactions. We map the DFT+$U$ results of several magnetic configurations to the Heisenberg spin model Hamiltonian to estimate Heisenberg exchanges. We demonstrate that the number of magnetic configurations should be at least twice the number of exchange parameters to estimate exchange parameters correctly. To calculate biquadratic interaction, we propose specific non-collinear magnetic configurations that do not change the energy of the Heisenberg spin model. We use classical Monte Carlo (MC) simulations to evaluate DFT+$U$ results. We obtain the temperature dependence of magnetic susceptibility and specific heat to determine the Curie-Weiss and Néel temperatures. The MC simulations reveal that although the biquadratic interaction can not change the Néel temperature, it modifies the order parameter. We indicate that for a fair comparison between classical MC simulations and experiments, we need to consider the quantum effect by applying $(S+1)/S$ correction in classical MC simulations.
