Yan Ni,Yongxiang Guo,Yuan-Yuan Jiang,Ting Huang,Qiuxuan Mu,Feiyan Hou,Tiaoyang Li,Shaohao Wang,Zhen Zhang,Dingfu Shao,Xiangdong Ding,Tai Min,Tao Li
Chiral noncollinear magnetic nanostructures, such as skyrmions, are intriguing spin configurations with significant potential for magnetic memory technologies. However, the limited availability of 2D magnetic materials that host skyrmions with Curie temperatures above room temperature presents a major challenge for practical implementation. Chromium tellurides exhibit diverse spin configurations and remarkable stability under ambient conditions, making them a promising platform for fundamental spin physics research and the development of innovative 2D spintronic devices. Here, domain structures of Cr 0.85 Te nanoflakes synthesized via chemical vapor deposition are investigated, using magnetic force microscopy at room temperature. The results reveal that the domain width of the as-grown nanoflakes scales with the square root of their thicknesses. Notably, the emergence and annihilation of skyrmions are observed, which can be reversibly controlled by external magnetic fields and thermal excitation in ambient air. Micromagnetic simulations suggest that the emergence of skyrmions in Cr 0.85 Te nanoflakes arises from inversion symmetry breaking due to compositional gradients across the sample thickness, rather than the interfacial Dzyaloshinskii–Moriya interaction. These findings provide new insights into the mechanisms underlying skyrmion formation in 2D ferromagnets and open exciting possibilities for manipulating domain structures at room temperature, offering practical pathways for developing next-generation spintronic devices.
The whorls of localized moments in chiral magnetic structures, such as skyrmions, lead to a quantized topological charge, which may make them useful as next-generation information bits. So far, the most reliable way to detect the existence of skyrmions is by using the topological Hall effect, which stems from electron scattering by the emergent magnetic field manifesting the topological charge. Here we employ two-dimensional magnets to establish a magneto-optical hallmark of skyrmions, which we call the topological Kerr effect, using the recently discovered ferromagnet CrVI 6 as a material platform. The Kerr angle hysteresis loop of this non-centrosymmetric system exhibits two antisymmetric bumps that are absent in the centrosymmetric CrI 3 and VI 3 . We develop a minimal model to further identify the bumps as direct manifestations of the topological charge, thereby providing a magneto-optical fingerprint of skyrmions with broader applicability.
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