Abstract
A key parameter for the low-temperature magnetic coupling of in dinuclear lanthanide single-molecule magnets (SMMs) is the barrier resulting from the exchange and dipole interactions between the two moments. Here we extend the pseudospin model previously used to describe the ground state of dinuclear endofullerenes to account for variations in the orientation of the single-ion anisotropy axes and apply it to the two SMMs @ and @. While x-ray magnetic circular dichroism (XMCD) indicates the same Dy ground state in both molecules, the Dy-Dy coupling strength and the stability of magnetization is distinct. We demonstrate that both the magnitude of the barrier and the angle between the two moments are determined directly from precise temperature-dependent magnetization data to an accuracy better than . The experimentally found angles between the moments are in excellent agreement with calculated angles between the quantization axes of the two Dy ions. Theory indicates a larger deviation of the orientation of the Dy magnetic moments from the Dy bond axes to the central ion in @. This may explain the lower stability of the magnetization in @, although it exhibits a stronger exchange coupling than in @.
- Received 21 May 2021
- Revised 4 November 2021
- Accepted 8 November 2021
- Corrected 5 December 2022
DOI:https://doi.org/10.1103/PhysRevB.104.224401
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Corrections
5 December 2022
Correction: The copyright license statement was presented incorrectly and has been fixed.