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

Skyrmions是一种受拓扑保护的自旋织构，当磁性材料中存在铁磁和反对称交换相互作用之间的不平衡竞争时发生，因此要求时间反转和空间对称性都被打破。本博士将研究极磁相GaMo4X8 （X=S;Se）中可能出现的skyrmion相，这是由该材料家族最近的实验和理论工作所激发的。为了实现这一目标，学生将合成这些化合物的多晶粉末和单晶，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进行比较，使我们能够理解物理参数（如自旋-轨道耦合）对块体晶体中skyrmions的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