Accelerating Materials Innovation 

Manipulation of the anomalous Hall effect in magnetic topological insulator heterostructure MnBi2Te4/Bi2Te3 by Si substrate surface engineering

We developed an in situ Hall measurement setup and measured the anomalous Hall effect (AHE) in magnetic topological insulator heterostructures MnBi₂Te₄/Bi₂Te₃ grown on different Si(111) substrate surfaces. For the sample grown on the Si(111)- 7 x 7 surface, the AHE signal appears at 15 K and becomes larger by further cooling, showing that the Curie temperature T_c is 15 K. In contrast, although the T_c is the same, the AHE signal shows a local maximum at 10 K for the sample grown on the β-Bi/Si(111)- √3 x √3 surface. A plausible explanation for this peculiar behavior is the enhanced skew scattering caused by the Bi layer, or the presence of the states localized at the interfacial Bi layer, which will affect the Berry curvature of the system. Our results demonstrate the possibility to artificially control the property of a two-dimensional magnet by modification of the substrate surface with a single monatomic layer.

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Open and Closed Cycle Sample Manipulators

When aiming at high experimental energy resolution for ARPES measurement, it is crucial to achieve ultra-low sample temperatures to quench thermal broadening. This is possible with state-of-the-art cryo manipulators reaching sample temperatures from < 3.5 K and featuring up to 6 fully motorized axes for a large range of movements. The manipulators are available as open and closed cycle. Open cycle manipulators reach lower temperature specifications and are rapidly cooled down from room temperature to 10 K in 15 min. The low He consumption below 1 l/h at ultimate temperature and the possibility to operate with liquid nitrogen at higher temperatures ensure a low operating cost. Closed cycle manipulators have no He consumption providing unlimited holding time.

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