In-situ Correlation of Electrical (Magneto-) Transport Effects with Magnetic Textures in a Transmission Electron Microscope

Abstract:

Spintronics naturally relates magnetic phenomena to transport properties. For example, magnetometry measurements are used as an input parameter to explain the anomalous Hall effect. Recently, magnetic textures such as Skyrmions were related to intriguing transport observations such as the topological Hall effect. However, the stability of magnetic textures depends on the sample geometry, therefore, a correlation of magneto-transport and transmission electron microscopy (TEM) data is challenging, if not conducted on identical samples. To overcome this, we devised a measurement platform that allows for the conduction of magneto-transport measurements while simultaneously performing Lorentz-TEM (L-TEM) investigations. A special holder is used to measure transport data. Hall bar structures are prepared using conventional lithography on thin film samples or TEM lamellae cut from single crystals placed on a measurement chip with a SixN window. In Lorentz mode, the objective lens of the microscope applied a magnetic field perpendicular to the sample plane. Acquisition of L-TEM images and the Hall voltage as function of the magnetic field were conducted automatically. Our setup allows us to follow the field dependence of the Hall voltage while simultaneously monitoring the magnetic texture. First, we will present thin film Nickel samples demonstrating the general functionality of the setup. Then, we will present our experiments of the Heusler compound Mn1.4PtSn: On the one hand, this material is known to host interesting magnetic textures such as a helical phase, non-topological bubbles and anti-skyrmions. On the other hand, spintronic transport experiments in this material class already revealed fascinating features in the Hall signal attributed to the topological Hall effect. Our setup allows for the direct correlation of the Hall effect with the magnetic field dependent occurrence of both non-topological (NT) and topologically protected magnetic phases.

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