Time evolution of a pumped molecular magnet-A time-resolved inelastic neutron scattering study

• 成果类型: Article
• 署名作者: Reeder, T. R.; Titum, Paraj; Kindervater, J.; Stewart, V. J.; Ye, Q.; Qiu, Y.; Maliszewskyj, N.; Mcqueen, T. M.; Broholm, C. L.
• 署名单位: Johns Hopkins University; Johns Hopkins University; Johns Hopkins University Applied Physics Laboratory; National Institute of Standards & Technology (NIST) - USA; Johns Hopkins University; Johns Hopkins University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12502
• DOI: 10.1073/pnas.2415300121
• 发表日期: 2025-01-07
• 关键词: thermal-conductivity; magnetization; heat

摘要

Introducing an experimental technique of time-resolved inelastic neutron scattering (TRINS), we explore the time-dependent effects of resonant pulsed microwaves on the molecular magnet Cr8F8Piv16. The octagonal rings of magnetic Cr3+ atoms with antiferromagnetic interactions form a singlet ground state with a weakly split triplet of excitations at 0.8 meV. A 4.6 tesla field was applied to tune the splitting between two members of the triplet excited level | 1 i <-> | 2 i to resonance with 105 GHz (0.434 meV) microwaves. The time-dependent occupations of the ground state | 0 i , lower lying levels | 1 i and | 2 i , and higher energy states |) >= 3i were extracted during and after 20 s long microwave pulses incident along the (101) direction of a Cr8F8Piv16 crystal held at 1.9 K. At significantly elevated spin temperatures, we found underpopulation relative to thermal equilibrium of | 2 i and spin-lattice thermalization time scales ranging from 1.6(2) s to 5.7(2) s depending on the power level. This contrasts with the relaxation time r 1 ( T -> 0) = 27(5) mu s inferred for | 2 i from in situ Electron Spin Resonance measurements. By probing a broad range of excited states during intense microwave pumping, TRINS thus provides a first view of long lived excited states in a molecular antiferromagnet.