Single magnetic atoms on surfaces can be utilized to build artificial structures with application in information technology, for instance data storage [1]. Making use of this atomic “Lego” allows also to create larger quantum spin systems with new emergent properties (Fig. 1). Often the magnetic properties of the individual atomic spins are already well known, so that the design of artificial structures can be done ahead by simulation and then subsequently measured experimentally (In this case with scanning tunneling microscopy and single atom electron spin resonance [2]). This gives a unique opportunity to explore and test emergent properties from single spins, atom by atom.

The goal of this thesis project is to develop a versatile software platform to construct the spin Hamiltonian of assemblies of single magnetic atoms.

               H= ∑JijSi⋅Sj+∑igμBBext⋅Si               

The parameters will be based on experimental data obtained from different species of single magnetic atoms (e.g. Titanium, Copper, Iron, Holmium, Dysprosium) [3,4,5]. With the help of your software you will simulate new spin ensembles from these different atomic species hunting for novel, emergent and exotic properties. In case of a master project, this project will be supplemented by additional experimental measurements of these systems.

Please contact Dr. Philip Willke, PHI (philip.willke@kit.edu) for further information and interest in the position.         

[1] Loth, S., Baumann, S., Lutz, C. P., Eigler, D. M., & Heinrich, A. J. Bistability in atomic-scale antiferromagnets. Science, 335(6065), 196-199 (2012).

[2] Baumann, S., et al. Electron paramagnetic resonance of individual atoms on a surface. Science, 350(6259), 417-420 (2015).

[3] Choi, T., ..., PW, et al. Atomic-scale sensing of the magnetic dipolar field from single atoms. Nature nanotechnology, 12(5), 420-424. (2017).

[4] Natterer, F. D., … PW, et al. Reading and writing single-atom magnets. Nature, 543(7644), 226-228. (2017).

[5] Yang, K., PW, et al. Electrically controlled nuclear polarization of individual atoms. Nature nanotechnology, 13(12), 1120-1125 (2018).

Fig. 1. Two structures of 5 iron atoms on a surface (top). Using the STM tip different structures can be „built“ that show greatly different signatures in electron spin resonance experiments (below) [3].