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Topology and spin dynamics in magnetic molecules

S. Carretta·P. Santini·G. Amoretti·M. Affronte·A. Ghirri·I. Sheikin·S. Piligkos·G. Timco·R. E. P. Winpenny
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Abstract

We investigate the role of topology and distortions in the quantum dynamics of magnetic molecules, using a cyclic spin system as reference. We consider three variants of antiferromagnetic molecular ring, i.e. Cr$_8$, Cr$_7$Zn and Cr$_7$Ni, characterized by low lying states with different total spin $S$. We theoretically and experimentally study the low-temperature behavior of the magnetic torque as a function of the applied magnetic field. Near level crossings, this observable selectively probes quantum fluctuations of the total spin (''$S$ mixing") induced by lowering of the ideal ring symmetry. We show that while a typical distortion of a model molecular structure is very ineffective in opening new $S$-mixing channels, the spin topology is a major ingredient to control the degree of $S$ mixing. This conclusion is further substantiated by low-temperature heat capacity measurements.

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S. Carretta, P. Santini, G. Amoretti, M. Affronte, A. Ghirri, I. Sheikin, S. Piligkos, G. Timco, R. E. P. Winpenny. 2004-12-22. Topology and spin dynamics in magnetic molecules. https://doi.org/10.1103/physrevb.72.060403

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