Spectroscopic Studies of the Magnetic Excitation and Spin-Phonon Couplings in a Single-Molecule Magnet

Shelby E. Stavretis, Duncan H. Moseley, Fan Fei, Hui Hui Cui, Yongqiang Cheng, Andrey A. Podlesnyak, Xiaoping Wang, Luke L. Daemen, Christina M. Hoffmann, Mykhaylo Ozerov, Zhengguang Lu, Komalavalli Thirunavukkuarasu, Dmitry Smirnov, Tieyan Chang, Yu Sheng Chen, Anibal J. Ramirez-Cuesta, Xue Tai Chen, Zi Ling Xue

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Large separations between ground and excited magnetic states in single-molecule magnets (SMMs) are desirable to reduce the likelihood of spin reversal in the molecules. Spin-phonon coupling is a process leading to magnetic relaxation. Both the reversal and coupling, making SMMs lose magnetic moments, are undesirable. However, direct determination of large magnetic states separations (>45 cm−1) is challenging, and few detailed investigations of the spin-phonon coupling have been conducted. The magnetic separation in [Co(12-crown-4)2](I3)2(12-crown-4) (1) is determined and its spin-phonon coupling is probed by inelastic neutron scattering (INS) and far-IR spectroscopy. INS, using oriented single crystals, shows a magnetic transition at 49.4(1.0) cm−1. Far-IR reveals that the magnetic transition and nearby phonons are coupled, a rarely observed phenomenon, with spin-phonon coupling constants of 1.7–2.5 cm−1. The current work spectroscopically determines the ground–excited magnetic states separation in an SMM and quantifies its spin-phonon coupling, shedding light on the process causing magnetic relaxation.

Original languageEnglish
Pages (from-to)15846-15857
Number of pages12
JournalChemistry - A European Journal
Volume25
Issue number69
DOIs
StatePublished - Dec 10 2019

Funding

The authors thank financial support by the US National Science Foundation (CHE-1633870 and CHE-1900296 to Z.-L.X.), Department of Navy HBCU/MI program (K.T.), and a Shull Wollan Center Graduate Research Fellowship (S.E.S.). Acknowledgement is also made to the Donors of the American Chemical Society Petroleum Research Fund for partial support of this work and to Jonathan Ludwig for help. This research used resources at the Spallation Neutron Source, a Department of Energy (DOE) Office of Science User Facility operated by ORNL. Computational resources for the VASP DFT calculations were made available through the VirtuES and ICE-MAN projects, funded by the Laboratory Directed Research and Development at ORNL. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by NSF Cooperative Agreement No. DMR-1644779 and the State of Florida. NSF′s ChemMatCARS Sector 15 is principally supported by the Divisions of Chemistry (CHE) and Materials Research (DMR), NSF, under grant number NSF/CHE-1834750. Use of the Advanced Photon Source, an Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory, was supported by the DOE under Contract No. DE-AC02-06CH11357.

Keywords

  • cobalt
  • magnetic transitions
  • single-molecule magnets (SMMs)
  • spin-phonon coupling
  • vibrational spectroscopies

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