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MA: Fachverband Magnetismus

MA 40: Molecular Magnetism

MA 40.6: Vortrag

Donnerstag, 14. März 2013, 16:30–16:45, H23

Unconventional Magnetic Properties of the Antiferromagnetic Heisenberg Model on Two Linked Dodecahedra — •Nikolaos P. Konstantinidis — Fachbereich Physik und Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany

The antiferromagnetic Heisenberg model has been shown to possess a non-trivial magnetic response in an external field for spins located on the vertices of a dodecahedron [1,2]. Here a first step towards a lattice of dodecahedra is taken by considering two dodecahedra linked along one of their faces with varying exchange coupling. The competition between intramolecular frustration, intermolecular coupling and magnetic field leads to a richer phase diagram compared to the single dodecahedron case. In the case of classical spins, the magnetization response may contain up to six magnetization discontinuities. In the full quantum case s_i=1/2 the states are characterized by the full symmetry of the Hamiltonian, and for weak intermolecular couplings there can be up to two magnetization discontinuities in a field. These discontinuities are unexpected for the antiferromagnetic Heisenberg model, which lacks magnetic anisotropy, and are a direct consequence of the exchange coupling geometry and its competition with the field. These results show the potential for non-trivial magnetic properties in structures build up from dodecahedra.

[1] N. P. Konstantinidis, Phys. Rev. B 72, 064453 (2005).

[2] N. P. Konstantinidis, Phys. Rev. B 76, 104434 (2007).