Two-dimensional ferromagnetic materials with topological structures have important application prospects in the field of spintronic information storage devices. As a result, the search for such a magnetic state with a unique spin structure has never stopped.

Recently, Professor Zhang Ying from the Institute of Physics of the Chinese Academy of Sciences, Beijing National Laboratory for Condensed Matth Physics and Songshan Lake Materials Laboratory, together with Professor Wang Shouguo of Beijing Normal University and Professor Lei Hechang of Renmin University of China, directly observed unconventional (anti-) wheat thread chains in domain wall pairs in the Fe5-xGeTe2 of two-dimensional ferromagnetic materials without an applied electric field, this is closely related to the significant enhancement of magnetization in the plane and the weak van der Waals interaction. At the same time as the anomalous magnetic transition, the researchers also observed a significant topological Hall effect. It is worth mentioning that the study also used PicoFemto®A series of low-temperature in-situ TEM-STM sample rods realized in-situ electrical regulation of two-dimensional ferroelectric materials at low temperatures, and observed the overall movement of the wheat thread chain on the domain wall. This study not only provides an experimental basis for the prediction of the topology of magnetic domain walls, but also provides new research methods for the fields of electronics, spintronics, and condensed matter physics. The relevant research results are published in "Adv. Mater." under the title of "Spontaneous (Anti)meron Chains in the Domain Walls of van der Waals Ferromagnetic Fe5-xGeTe2". On.

DOI:10.1002/adma.202005228

Figure: In-situ TEM Force-Electrical Test at Low Temperature

In-situ TEM Force-Electrical Test at Low Temperature Using PicoFemto from Zeyu Technology®A series of low-temperature in-situ TEM-STM sample rods. The sample is mounted on a fixed sample loading end. The sample can be refrigerated through a liquid nitrogen system. The tungsten needle at the three-dimensional manipulation end is accurately mounted on the specified position of the sample and realizes mechanical loading and electrical measurement at low temperature. It can be seen from the in-situ video that the sample rod maintains high stability at low temperature and electrical regulation. In the experiment, the overall movement of the wheat thread chain on the domain wall with the change of the applied electrical signal can be clearly observed.

Figure: Low temperature force-electric sample rod used in this article