Anisotropy, Geometric Structure and Frustration Effects in Molecule-Based Nanomagnets
G. Kamieniarza, P. Kozłowskia, M. Antkowiaka, P. Sobczaka, T. Ślusarskia, D.M. Tomeckaa, A. Barasińskib, B. Brzostowskib, A. Drzewińskib, A. Bieńkoc and J. Mrozińskic
aFaculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
bInstitute of Physics, University of Zielona Góra, Poland
cFaculty of Chemistry, University of Wrocław, Poland
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In this paper we review our results of comprehensive study of molecular nanomagnets recently synthesized in the form: of the chromium-based molecules and bimetallic copper-containing chains as well as we present some new findings. We focus on effects of anisotropy, geometry and frustration appearing in various thermodynamic properties of the nanoscale magnets which are described by Heisenberg-like spin models and simulated by accurate numerical methods. We show that bond-dependent exchange anisotropy is needed to model magnetic torque in the Cd-doped chromium ring. We argue that only in the limit of infinite rings (n→ ∞) frustration can be considered as the opposite to bipartiteness in the odd numbered (3 ≤ n ≤ 9) s = 3/2 quantum spin rings. We analyse the influence of exchange interactions and anisotropy on magnetic susceptibility of bimetallic (S = 3/2, s = 1/2) chains composed of Cu ions linked to different 3d ions by fitting experimental data. We reach the remarkable consistency of the density functional theory estimates of the magnetic couplings in Cr8 molecule and provide strong support to the spin models exploited in the literature.
DOI: 10.12693/APhysPolA.121.992
PACS numbers: 75.50.Xx, 75.10.Jm, 75.10.Pq, 75.40.Cx