Title: Interplay of ferromagnetism, nematicity and Fermi surface nesting in kagome flat band Show Chinese title

Title: 石墨烯平坦带中铁磁性、向列性和费米面嵌套的相互作用

Abstract: Recent experiment on Fe-doped CoSn has uncovered a series of correlated phases upon hole doping of the kagome flat bands. Among the phases observed, a nematic phase with a six- to two-fold rotation symmetry breaking is found to prevail over a wide doping and temperature range. Motivated by these observations, we investigate the interaction-driven phases realized in a kagome model with partially filled, weakly dispersing flat bands. Density-density interactions up to second-nearest neighbors are considered. We identify a close competition between ferromagnetic and nematic phases in our self-consistent Hartree-Fock calculations: while on-site interaction favors ferromagnetism, the sizable inter-sublattice interactions stabilize nematicity over a wide doping window. Competition from translational-symmetry-breaking phases is also considered. Overall, our results show that nematicity is a generic outcome of partially filled kagome flat bands and establish a minimal framework for understanding correlated flat-band phases. Show Chinese abstract

Abstract: 最近对掺铁的CoSn进行的实验揭示了在kagome平带空穴掺杂时的一系列关联相。 在观察到的相中，发现一种六重对称性到二重对称性破缺的向列相在广泛的掺杂和温度范围内占主导地位。 受这些观察结果的启发，我们研究了部分填充、弱色散平带的kagome模型中实现的相互作用驱动相。 考虑了至第二近邻的密度-密度相互作用。 我们在自洽的Hartree-Fock计算中识别出铁磁相和向列相之间的紧密竞争：虽然局域相互作用有利于铁磁性，但显著的亚格子间相互作用在广泛的掺杂窗口内稳定了向列性。 也考虑了来自平移对称性破缺相的竞争。 总体而言，我们的结果表明向列性是部分填充kagome平带的普遍结果，并建立了一个理解关联平带相的最小框架。