10 October 2025
Europe/Berlin timezone

Quantum material emulation via atom-by-atom assembly

10 Oct 2025, 11:00
15m
Speaker MIN Quantum Science and Technologies Quantum Science & Technologies

Speaker

Jens Wiebe (Universität Hamburg)

Description

With the tip of a scanning tunnel microscope as a tool, atoms can be assembled into one (1D)- or two-dimensional (2D) lattices on solid material surfaces (1,2). Simultaneously their spin-resolved spectral functions can be measured one atom at a time (3,4). Combining spin-carrying transition metal or rare earth atomic lattices with different substrates such as normal metals (2,4-7), semiconductors (8), or superconductors (9), the hybrid systems emulate a vast variety of quantum materials. Their parameters can be widely tuned by the choice of lattice and atom species, the substrates' material and surface orientation, and the resulting topology. Thereby, these systems can be directly compared to and used for the optimization of simulation methods ranging from DMRG (10) over NRG (11), and tight binding models (12-15), to ab-initio based advanced many-body theories (6,8,11) and KKR methods (2,7,16,17) solving the Kohn-Sham-Dirac-BdG equations (18). I will review our research on such artificial spin arrays conducted in the scanning probe methods group of the MIN faculty over the past 20 years (3) involving our fruitful collaborations with different theory groups. We started with quasiclassical spin Hamiltonians along with isotropic (Heisenberg) (2), Dzyaloshinskii-Moriya (10), and symmetric anisotropic (17) RKKY-type exchange contributions to demonstrate proof-of-principle realizations of spintronic devices (5,8,16,17). More recently, we have utilized superconducting substrates to exploit competing Kondo and Cooper pairing interactions (9,11). Thereby, we have realized p-wave pairing correlations in 1D manganese chains coupled to elemental niobium (12) aiming at the emulation of the Kitaev chain Hamiltonian and the predicted Majorana edge modes (13,18). Finally, we implemented minimal-invasive non-local detection schemes for such fragile quantum states (14,15). I will finish with a prospect of future research directions towards spatially-, spin- and time-resolved spectroscopy and van der Waals materials.
Latest work was supported by the Cluster of Excellence 'Advanced Imaging of Matter' (EXC 2056 - project ID 390715994) of the Deutsche Forschungsgemeinschaft (DFG) and by the DFG - project WI 3097/4-1 (project No. 543483081).
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https://doi.org/10.1103/RevModPhys.91.041001
(2) A. Khajetoorians, JW, B. Chilian, S. Lounis, S. Blügel, and R. Wiesendanger, Nat. Phys. 8, 497 (2012).
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(4) F. Meier, L. Zhou, JW, and R. Wiesendanger, Science 320, 82 (2008).
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(6) A. Khajetoorians, M. Valentyuk, M. Steinbrecher, T. Schlenk, A. Shick, J. Kolorenc, A. I. Lichtenstein, T. O. Wehling, R. Wiesendanger, and JW, Nat. Nanotechnol. 10, 958 (2015).
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(11) A. Kamlapure, L. Cornils, R. Žitko, M. Valentyuk, R. Mozara, S. Pradhan, J. Fransson, A. I. Lichtenstein, JW, and R. Wiesendanger, Nano Lett. 21, 16 (2021).
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https://journals.aps.org/prb/accepted/3e07cK88Qf81e70ed9ad2065e47f5e09476d83482

Author

Jens Wiebe (Universität Hamburg)

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