Synthesis, structural and physical characterisation of lacunar spinels hosting Neel-type skyrmions

Skyrmions是一种拓扑保护的自旋织构，当磁性材料中存在铁磁和反铁磁交换相互作用之间的不平衡竞争时发生，因此要求时间反演和空间对称性都被破坏。本博士将调查可能出现的skyrmion阶段在极性磁相GaMo 4 X 8（X=S;Se）的动机最近的实验和理论工作在这个家庭的材料。为了实现这一目标，学生将合成这些化合物的多晶粉末和微晶，并进行详细的结构和磁性研究。这将涉及粉末和单晶中子散射方法，如极化中子分析和小角中子散射测量。通过这些不同的测量方法建立的磁相图将与经典自旋海森堡的蒙特卡罗模拟相结合，使我们能够理解物理参数如自旋轨道耦合对体晶体中skyrmions稳定性和尺寸的影响。

Skyrmions are topologically protected spin texture occurring when abalanced competition between ferromagnetic and antisymmetricexchange interactions is present in a magnetic material and thereforerequire that both time reversal and spatial symmetry are broken. ThisPhD will investigate the possible emergence of a skyrmion phase inthe polar magnetic phases GaMo4X8 (X=S;Se) motivated by recentexperimental and theoretical work in this family of materials. Toachieve the student will synthesise polycrystalline powders and singlecrystals of these compounds and carry out a detailed structural andmagnetic study. This will involve powder and single crystal neutronscattering methods such as polarised neutron analysis and smallangle neutron scattering measurements. The magnetic phasediagram established by these various measurement methods will becompared with Monte Carlo simulation of a classical spin Heisenbergallowing us to understand the impact of physical parameters such asspin-orbit coupling on the stability and size of skyrmions in bulkcrystals