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Quantum phenomena in molecular-based nanomagnets

Project QUNA
Research Area Materials Science
Principal Investigator(s) Dr. Kamieniarz Grzegorz
Institution(s)
  • University Poznan, Department of Physics, Poznan, Poland
  • Universita di Firenze, Dipartiment di Chimica, Firenze, Italy
  • University of Manchester, School of Chemistry, Manchester, UK

Abstract

Molecular-based metallic clusters and chains behave like individual quantum nanomagnets, displaying quantum phenomena on macroscopic scale. In view of potential applications of such materials in magnetic storage devices or in envisaged quantum computer processor as well as in the low-temperature refrigerants, the accurate simulation of these complex objects becomes the key issue. The magneto-structural correlations, the role and mechanism of magnetic anisotropy and intrinsic quantum effects following from the geometrical frustration induced by the topological arrangement of spins or particular interactions count among the new challenges for computer simulations.
The simulations planned in the QUNA project address the quantum phenomenological models which are the most reliable theoretical representatives of the physical molecular-based nanomagnets investigated recently and their reliability from the fundamental microscopic point of view assessed by the well established first-principle electronic structure calculations. Exploiting a number of deterministic verified techniques (exact diagonalization, quantum transfer matrix , density-matrix renormalization group), the model calculations will be performed without any uncontrolled approximations and will be numerically accurate.
The chromium-based rings which are outstanding materials for quantum information processing and for low-temperature cooling will be the principal objects of investigation. The real challenges appear for the molecules containing more than eight CrIII S=3/2 ions and/or are doped by magnetic NiII or CuII ions, nevertheless the exact energy spectra, S-mixing, the total spin oscillations essential for quantum coherence and frustration phenomena important for magnetic refrigeration will be accomplished. Interesting behaviour characteristic of single-chain magnets for canted MnIII antiferromagnetic chains with magneto-structural correlations and for rare-earth compounds with interaction-driven frustration will be addressed in the framework of quantum approach.

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