Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 21: Frustrated Magnets I
MA 21.7: Talk
Wednesday, March 19, 2025, 11:15–11:30, H18
NMR study of the field-induced magnetic states in Cu-based mineral Cu2(OH)3NO3 — •Yoshihiko Ihara1, Issei Niwata1, Aswathi M. Chakkingal2, Dmytro Inosov2, and Darren Peets2 — 1Hokkaido University, Sapporo, Japan — 2TU Dresden, Dresden, Germany
Magnetic ground states are stabilized at low temperature by minimizing the energy costs for magnetic moments interacting with each other. When the interactions compete by geometrical frustration in the case of a non-bipartite lattice or by the bond-dependent sign of interactions, the magnetic ground state cannot be easily selected and the perturbation by external fields can modify the ground state introducing a nontrivial magnetic state with intriguing properties. Here, we focus on the Cu-based mineral rouaite, Cu2(OH)3NO3, in which S=1/2 Cu2+ spins construct both ferromagnetic (FM) and antiferromagnetic (AFM) chains in a unit cell. Competing FM and AFM interactions result in complicated field-temperature phase diagram with at least three different magnetic states. We study the magnetic structure and the low-energy magnetic excitations by measuring the NMR spectra and the nuclear spin-lattice relaxation rate. The low-field magnetic structure is identified and compared with the results of neutron diffraction measurements. We will also discuss the external magnetic field effect on the magnetic ground state from the results of NMR measurements at higher magnetic fields.
Keywords: Quantum magnet; Magnetic structure; Magnetic excitations; Nuclear magnetic resonance