2023年7月19日

赫斯勒的3 d模型:单个水晶样品化合物,通过定制的离子光束的厚度、显示。磁畴结构(黑线)形成的磁场的影响下。信贷:b·施罗德/ HZDR Skyrmions微观磁漩涡,可以形成在某些材料。在2009年第一次发现,他们感兴趣的研究人员,因为他们可以利用新形式的数据存储。理论家预测,也有所谓的antiskyrmions skyrmions发现10年之后。研究者从HZDR, MPI论坛,IFW德累斯顿和南佛罗里达大学的现在使用离子束看到和精密测量技术的这一复杂的现象,他们报告在《通讯材料。“从某种意义上说,一个antiskyrmion skyrmion的反粒子。这两个被称为内部,欠它们的属性的集体互动大量粒子在固体物质。他们的性质有很大的不同从他们的潜在的基本粒子,”托尼博士说执掌德累斯顿高磁场实验室(HLD) HZDR。舵使用一个比喻来说明两个粒子的行为:“在特殊材料、微观skyrmion漩涡形成的磁性粒子和行为非常奇怪。 A 'magnetic' seafarer approaching them would either be attracted or repelled. Antiskyrmions, on the other hand, would be almost impossible to find because these peculiar 'anti' vortices combine the different behaviors of skyrmions within themselves." A characteristic footprint hidden in electrical signals As the analogy suggests, antiskyrmions are quite difficult to detect. But Helm's team followed a theoretical prediction that points to a way to discover them. Due to their unique geometric properties—their topology—antiskyrmions cause additional voltage in the electrical conduction of the material. The team combined electrical measurement methods with magneto-optical microscopy to reveal the electrical signature of antiskyrmions in the material studied for the first time. The characteristic footprint of the magnetic anti-vortex is hidden in the so-called Hall effect. To attain it, an external magnetic field is applied perpendicularly to the direction of the current and deflects it. Any topological vortices that are present generate a local magnetic field that causes additional voltage. According to the theory, this signal is directly connected with the topology of the vortices. This is how skyrmions could be distinguished from antiskyrmions—by measuring the Hall effect. "Our study suggests that this contribution is extremely small and that the signature measured is mainly due to the magnetic properties of the antiskyrmions. Our results help to distinguish the actual Hall signature better from other effects and give a first estimate of its magnitude, which refutes previous research results," Helm says. Scalable: The smaller, the more structured For the study, Helm's team used a particular magnetic compound from the class of Heusler compounds, made of the metals platinum, manganese, and tin. These crystalline compounds behave differently than their composition would suggest. For example, they are ferromagnetic, although none of their elementary building blocks is ferromagnetic in itself. Under certain conditions, various topological structures such as skyrmions or antiskyrmions can form in the compound studied. And the scientists noticed another fascinating detail: The size of the antiskyrmions depends on, and can be controlled via, the thickness of the sample. "They are not detectable in a big chunk of starting material, but they do occur when the material is cut into flat slices less than 10 micrometers thick," Helm explains. The physicists used a kind of ion beam gun to saw the crystals of the starting material into tiny pieces. Scalability plays a crucial role in technological applications. Nanoscale devices are needed, for example, to create novel magnetic storage and data transmission systems based on quasiparticles. In collaboration with colleagues from the HZDR Ion Beam Center, the team researched further properties of the material and incorporated these insights into supplementary theoretical calculations and simulations. Helm's team was thus able to substantiate the existence of antiskyrmions and show precisely how they can form in a highly complex magnetic environment. More information: Moritz Winter et al, Antiskyrmions and their electrical footprint in crystalline mesoscale structures of Mn1.4PtSn, Communications Materials (2022). DOI: 10.1038/s43246-022-00323-6