Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 57: Correlated Magnetism – Kagome Systems

TT 57.1: Talk

Wednesday, March 11, 2026, 15:00–15:15, CHE/0091

Probing Spin Dynamics and Hyperfine Coupling in the Frustrated Quantum Magnet Clinoatacamite: An NMR Study — •Roni Bose¹, Hans-Joachim Grafe¹, Bernd Büchner¹, Anja U. B. Wolter¹, Leonie Stödter³, Caroline Kastner², and Stefan Süllow² — ¹IFW Dresden, Helmholtzstraße 20, 01069, Germany — ²IPKM, TU Braunschweig, Braunschweig, Germany — ³FZ Jülich, JCNS at MLZ, Garching, Germany

Recent work on Atacamite reveals a quantum critical point above 21.9 T with a dimensional reduction from 3 D AFM ordering to 1 D quantum spin liquid behavior. Clinoatacamite has same chemical formula as Atacamite, but displays distinct magnetic behaviour due to different crystal structure. Previous µSR studies on polycrystals reveal coexistence of long range magnetic ordering and fluctuations below 18 K, which transforms into a metastable state below 6.5 K, while neutron-diffraction observes magnetic reflections only below 6.5 K, but not below 18 K.

To address the discrepancy in reported ordering temperatures and to investigate the magnetic behaviour below 18 K, we performed ¹H-NMR measurements with magnetic field orientations B ∥ [201] (perpendicular to the Kagome plane) and B ∥ [010]. For both field directions, the NMR spectra show splittings near 18 K and again near 6 K, indicating magnetic transitions. Furthermore, the temperature dependence of the spin-lattice relaxation rate at different proton sites reveals a coexistence of partial spin freezing and strong fluctuations below 18 K, followed by a fully ordered state below 6 K.

Keywords: Clinoatacamite; Atacamite; NMR Spectroscopy; Kagome plane; Spin freezing