SPICE Workshop on Quantum Functionalities of Nanomagnets, June 17th - 19th 2025
Thore Posske
When crossing over to the quantum regime, magnetic systems behave significantly differently. For instance, magnetic helices and skyrmions cannot easily be found in the ground state in translationally invariant systems, at least in the absence of spontaneous symmetry breaking. Yet, almost classical behavior can survives at special system parameters. Here, we report on phenomena that live on the edge of the quantum crossover: Product eigenstate helices at the critical point between ferromagnetic and frustrated systems, their multi-dimensional extensions, and their adiabatic creation. Interestingly, we find a large degeneracy of the associated eigenspaces, and a Z_n effect in their creation, i.e., the system revisits the ground state only after n cycles of the adiabatic evolution. If time allows, we also address the dynamics of quantum skyrmions as an example how machine learning techniques can help us to shed light on quantum spin systems.
References:
All product eigenstates in Heisenberg models from a graphical construction,
F Gerken, I Runkel, C Schweigert, T Posske
Physical Review Research 7, L012008 (2025)
Generalized Josephson effect with arbitrary periodicity in quantum magnets
A Tripathi, F Gerken, P Schmitteckert, M Thorwart, M Trif, T Posske
arXiv preprint arXiv:2408.04008 (2024)
Quantum skyrmion dynamics studied by neural network quantum states
A Joshi, R Peters, T Posske
Physical Review B 110 (10), 104411 (2024)