标题： 自旋结构和磁场下自旋-$\frac{5}{2}$三角晶格反铁磁体Na$_2$BaMn(PO$_4$)$_2$的相图 显示英文标题

标题： Spin structures and phase diagrams of the spin-$\frac{5}{2}$ triangular-lattice antiferromagnet Na$_2$BaMn(PO$_4$)$_2$ under magnetic field

摘要： 我们结合单晶中子衍射研究和蒙特卡洛模拟来确定自旋-5/2三角晶格反铁磁体Na$_2$BaMn(PO$_4$)$_2$在磁场中的自旋结构和有限温度相图。在两个不同方向施加磁场，即沿$c$轴和三斜对称性的$ab$平面，我们跟踪自旋结构通过磁传播矢量变化的演化。我们通过一个包含易轴各向异性和弱的、受挫的层间耦合以及层内交换作用的最小海森堡哈密顿量来解释这些结果。在表示分析的指导下，我们将对称性允许的模式与测量强度进行精修，并获得所有场诱导相的自旋结构，我们将这些结构与模拟配置进行定量比较。 综合来看，我们的测量和模拟表明，受挫的层间交换作用——而不是纯粹的二维物理——组织了Na$_2$BaMn(PO$_4$)$_2$中出人意料的丰富场诱导相。 显示英文摘要

摘要： We combine single-crystal neutron diffraction studies and Monte Carlo simulations to determine the spin structures and finite-temperature phase diagram of the spin-5/2 triangular-lattice antiferromagnet Na$_2$BaMn(PO$_4$)$_2$ in magnetic field. With the application of a magnetic field in two different directions, namely along the $c$-axis and in the $ab$-plane of the trigonal symmetry, we track the evolution of the spin structure through changes of the magnetic propagation vector. We account for these results with a minimal Heisenberg Hamiltonian that includes easy-axis anisotropy and weak, frustrated interlayer couplings in addition to intralayer exchange. Guided by representation analysis, we refine symmetry-allowed modes to the measured intensities and obtain the spin structures for all field-induced phases, which we compare quantitatively with simulated configurations. Taken together, our measurements and simulations show that frustrated interlayer exchange -- rather than purely 2D physics -- organizes the unexpectedly rich field-induced phases of Na$_2$BaMn(PO$_4$)$_2$.