Exploring materials for future spintronics

Magnetoelectronic transport properties of noncollinear antiferromagnets

Antiferromagnetic materials with a noncollinear magnetic structure play a vital role in the emerging field of antiferromagnetic spintronics. For instance, in contrast to what one might expect, these materials can exhibit a large anomalous Hall effect despite a tiny magnetization arising from an intrinsic property of the electronic band structure and from breaking certain symmetry relations. Currently, we are investigating the electronic transport properties and microwave absorption of various Mn-based compounds to unravel the coupling between the magnetic and crystalline structure under mechanical strain. 

Phase transitions associated with magnetic-field induced topological orbital momenta in a non-collinear antiferromagnet. Deng, S.; Gomonay, O.; ChenJ.; Fischer G.; He L.; Wang, C.; Huang, Q.; Shen F.; Tan Z.; Zhou R.; Hu Z.; Šmejkal L.; Sinova J.; Wernsdorfer W.; Sürgers C. Nature Communications 15:822 (2024) https://doi.org/10.1038/s41467-024-45129-x

Controlling Chiral Spin States of a Triangular‐Lattice Magnet by Cooling in a Magnetic Field. Deng, S.; Fischer, G.; Uhlarz, M.; Wosnitza, J.; Bohnen, K.; Heid, R.; Wang, C.; Sürgers, C. Advanced Functional Materials, 29, Article No.1900947 (2019). doi:10.1002/adfm.201900947


Spininjection and spinmanipulation in CMOS-compatible heterostructures

In this cooperative project between the Physikalische Institut (PHI) at KIT and the Institute of Semiconductortechnology (IHT) at the University of Stuttgart we aim to demonstrate spininjection, -detection and –manipulation in CMOS-compatible devices. The project was supported by the Deutsche Forschungsgemeinschaft (DFG) until 2020. Recently, we investigated the anomalous Nernst effect of Mn5Ge3Cx films on sapphire and Ge substrates demonstrating a strong increase of the anomalous Nernst effect due to C incorporation.

Anomalous Nernst effect of a ferromagnetic film on a semiconductor. Deng, S.; Kraft, R.; Fischer, G.; Sürgers, C. Appl. Phys. Lett. 117, 262402 (2020). https://doi.org/10.1063/5.0033683

Detecting mechanical strain by NV-center spectroscopy

LogoWe propose to implement a new experimental technique based on optically detected nitrogen-vacancy (NV) color centers in diamond. We will extend this method by application to two-phase heterostructures comprising a metallic thin film deposited on a diamond membrane containing NV centers located close to the film/membrane interface. By this approach we will be able to sense the local intrinsic strain of the film by optical read-out of the NV-center energy states. The power of this method will be demonstrated by investigating metallic antiferromagnets with non-collinear spin arrangements currently investigated in our group. The project is part of the collaborative research center TRR288 "Elastic Tuning and Response of Quantum Phases of Matter" (Frankfurt - Karlsruhe - Mainz) supported by the DFG since 2020.


Experimental methods

  • Thin film and multilayer deposition (various methods)
  • Electron diffraction, x-ray diffraction, magneto-optical spectroscopy
  • Electronic transport measurements (resistivity, Hall effect, Nernst effect, electric-field effect) at low temperatures and in magnetic fields

Current collaborations

Christoph Sürgers

Researcher ID-2873-2013