Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Spins on surfaces at the atomic scale II
O 89.1: Vortrag
Donnerstag, 12. März 2026, 15:00–15:15, WILL/A317
Magnetization Curves of Antiferromagnetic Spin Chains: Probing the Quantum to Classical Crossover — •Henrik Lichtl1,2, Lukas Veldman1,2, Nicolaj Betz1,2, Johannes Schust1, Laëtitia Farinacci1,3, Fernando Delgado4, Susanne Baumann1, and Sebastian Loth1,2 — 1University of Stuttgart, Institute for Functional Matter and Quantum Technologies. — 2Center for Integrated Quantum Science and Technology (IQST), University of Stuttgart. — 3Carl-Zeiss- Stiftung Center for Quantum Photonics Jena - Stuttgart - Ulm. — 4Instituto de Estudios Avanzados IUDEA, Departamento de Física, Universidad de La Laguna.
As the size of a magnetic structure increases it undergoes a transition from a quantum system to a classical magnet, yet the evolution of the magnetization behavior at this crossover is largely unexplored. Here we introduce an approach to record high-speed magnetization curves in a scanning tunneling microscope (STM), reaching magnetic field sweep rates of up to 40kT/s. We analyze the statistics of the transitions between the two antiferromagnetic ground states of antiferromagnetic Fe spin chains on a Cu2N surface, which allows us to distinguish between quantum and classical regimes in their magnetization curves. Quantum signatures diminish rapidly with size of the chain, where chains longer than five atoms already show characteristics of classical nanoscale magnets. Accessing such high-speed magnetization curves at the atomic scale brings concepts originally developed for bulk materials into the STM, offering insight into how quantum spins interact with their environment during the quantum-to-classical transition.
Keywords: Scanning tunneling microscopy; Nano magnetism; Spins on surfaces