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

Published

January 1, 2025

Author(s)

T. Reeder, Paraj Titum, J. Kindervater, Qiang Ye, Jose Rodriguez Rivera, Yiming Qiu, Nicholas C. Maliszewskyj, T. McQueen, Collin L. Broholm

Abstract

ntroducing 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|1i ↔ |2i to resonance with 105 GHz (0.434 meV) microwaves. The time-dependent occupations of the ground state |0i, lower lying levels |1i and |2i, and higher energy states |λ ≥ 3 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 |2i 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 τ1(T → 0) = 27(5) μ inferred for |2i 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.

Citation

Proceedings of the National Academy of Sciences

Volume

122

Issue

1

Pub Type

Journals

Download Paper

Local Download

Keywords

time resolved inelastic neutron scattering, molecular magnet

Citation

Reeder, T. , Titum, P. , Kindervater, J. , Ye, Q. , Rodriguez Rivera, J. , Qiu, Y. , Maliszewskyj, N. , McQueen, T. and Broholm, C. (2025), Time evolution of a pumped molecular magnet - a time resolved inelastic neutron scattering study, Proceedings of the National Academy of Sciences, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958468 (Accessed March 5, 2025)