标题： 基于CrTe$_2$的双层正交铁磁性 显示英文标题

标题： Bilayer orthogonal ferromagnetism in CrTe$_2$-based van der Waals system

摘要： 具有显著自旋各向异性的系统在推进磁化翻转和自旋波生成机制中起着关键作用，这对自旋电子技术至关重要。 准范德华铁磁体，特别是Cr$_{1+\delta}$Te$_2$化合物，在这一领域是开创性材料，因其在受挫层状几何结构与磁性之间的微妙平衡而闻名。 尽管进行了广泛的研究，它们的磁性基态的精确性质，通常被描述为倾斜铁磁体，仍然存在争议，同时在外加磁场和不同温度下自旋取向的机制也尚未明确。 在本工作中，我们采用多模式方法，结合互补技术，揭示出Cr$_{1+\delta}$Te$_2$ ($\delta = 0.25 - 0.50$) 拥有一种此前被忽视的磁性相，我们称之为正交铁磁性。 这种单一相由交替的原子级锐利的平面内和面外铁磁块层组成，通过交换相互作用耦合，因此与交叉磁性有显著不同，交叉磁性只能通过堆叠多个异质结构元件才能实现。 与之前报道的CrTe$_2$基系统中自旋取向的渐进变化相反，我们提供了明确的证据表明存在突然的自旋翻转类似转变。 这一发现可能是由于样品中结晶度的提高和缺陷密度的降低，使Cr$_{1+\delta}$Te$_2$化合物重新成为自旋电子学和轨道电子学应用的有希望的候选材料，为器件工程开辟了新的途径。 显示英文摘要

摘要： Systems with pronounced spin anisotropy play a pivotal role in advancing magnetization switching and spin-wave generation mechanisms, which are fundamental for spintronic technologies. Quasi-van der Waals ferromagnets, particularly Cr$_{1+\delta}$Te$_2$ compounds, represent seminal materials in this field, renowned for their delicate balance between frustrated layered geometries and magnetism. Despite extensive investigation, the precise nature of their magnetic ground state, typically described as a canted ferromagnet, remains contested, as does the mechanism governing spin reorientation under external magnetic fields and varying temperatures. In this work, we leverage a multimodal approach, integrating complementary techniques, to reveal that Cr$_{1+\delta}$Te$_2$ ($\delta = 0.25 - 0.50$) hosts a previously overlooked magnetic phase, which we term orthogonal-ferromagnetism. This single phase consists of alternating atomically sharp single layers of in-plane and out-of-plane ferromagnetic blocks, coupled via exchange interactions and as such, it differs significantly from crossed magnetism, which can be achieved exclusively by stacking multiple heterostructural elements together. Contrary to earlier reports suggesting a gradual spin reorientation in CrTe$_2$-based systems, we present definitive evidence of abrupt spin-flop-like transitions. This discovery, likely due to the improved crystallinity and lower defect density in our samples, repositions Cr$_{1+\delta}$Te$_2$ compounds as promising candidates for spintronic and orbitronic applications, opening new pathways for device engineering.