講演題目: NMR experiments under extreme conditions at the Dresden High Magnetic Field Laboratory
講師: Hannes Kuhne 氏
日時: 2026年10月5日(月)
場所: 未定
要旨:
The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is a research center of the Helmholtz Association with research programs in matter, health, and energy. Its Dresden High Magnetic Field Laboratory (HLD), a member of the European Magnetic Field Laboratory (EMFL), provides access to high magnetic fields and a broad range of experimental techniques [1]. In the first part of the talk, I will briefly introduce the HZDR and HLD, their research infrastructure and scientific activities, and their role within the European high-field research landscape [2].
The second part will focus on ¹H NMR experiments on superhydrides under ultrahigh pressure. Superhydrides exhibit superconducting transition temperatures approaching room temperature, while their microscopic investigation remains challenging because of the minute sample volumes available in diamond anvil cells. I will discuss how inductively coupled Lenz lenses enable NMR measurements on samples with dimensions of only a few tens of micrometers. Temperature-dependent ¹H NMR spectra and spin-lattice relaxation measurements on lanthanum superhydrides show signatures consistent with superconductivity and provide information on the superconducting gap [3]. In addition, enhancements of 1/T₁T observed below T₍c₎ in several superhydrides can be described within a Hebel–Slichter-type model and may point toward BCS-like superconductivity [4].
The third part will focus on the frustrated sawtooth-chain compound atacamite [5]. Angular-dependent ¹H NMR measurements using spherical two-axis sample rotation at low temperatures and high magnetic fields provide microscopic insight into the magnetically ordered state and the anisotropic hyperfine interaction. By combining static-field NMR up to 22 T with pulsed-field NMR at higher fields, we could track the suppression of long-range antiferromagnetic order at a field-induced quantum critical point near 22 T and investigate the high-field state characterized by a flattening of the magnetization near half saturation [6]. The results support a field-induced dimensional reduction in which the sawtooth-chain system effectively decouples into antiferromagnetic spin-1/2 Heisenberg chains formed by the basal spins in a field-polarized background of apical spins.
References
[1] https://www.hzdr.de/db/Cms?pNid=580&pLang=en
[2] https://emfl.eu
[3] D. Semenok et al., Adv. Sci. 13, e20701 (2026)
[4] F. Bärtl et al.,(under review)
[5] L. Heinze et al., Phys. Rev. Lett. 126, 207201 (2021)
[6] L. Heinze et al., Phys. Rev. Lett. 134, 216701 (2025)