标题： 自旋螺旋态在方形和三角形晶格交叉处的Nagaoka铁磁体的不稳定性 显示英文标题

标题： Spin-spiral instability of the Nagaoka ferromagnet in the crossover between square and triangular lattices

摘要： 我们研究在半填充附近介于正方形和三角形晶格之间的硬核费米-哈伯德模型。 正如Nagaoka在1960年代所认识到的，在正方形晶格上，单一空穴的存在会导致铁磁自旋有序。 在三角形晶格上，几何阻挫则会导致自旋单态基态，这可以与120度螺旋序相关联。 在介于正方形和三角形之间的晶格上，存在一个相变点，在该点铁磁序会不稳定地转变为自旋螺旋。 我们对这种不稳定性进行建模，找到了精确的临界点。 显示英文摘要

摘要： We study the hard-core Fermi-Hubbard model in the crossover between square and triangular lattices near half-filling. As was recognized by Nagaoka in the 1960s, on the square lattice the presence of a single hole leads to ferromagnetic spin ordering. On the triangular lattice, geometric frustration instead leads to a spin-singlet ground state, which can be associated with a 120-degree spiral order. On lattices which interpolate between square and triangular, there is a phase transition at which the ferromagnetic order becomes unstable to a spin spiral. We model this instability, finding the exact critical point.