Projects / Programmes
Study of one- and two-dimensional antiferomagnets with a spin gap
| Code |
Science |
Field |
Subfield |
| 1.02.00 |
Natural sciences and mathematics |
Physics |
|
| Code |
Science |
Field |
| P260 |
Natural sciences and mathematics |
Condensed matter: electronic structure, electrical, magnetic and optical properties, supraconductors, magnetic resonance, relaxation, spectroscopy |
antiferromagnets, spin gap, spin liquids, magnetic resonance
Researchers (7)
Organisations (2)
Abstract
Within this project we plan to study structural and magnetic properties of novel one- and two-dimensional antiferromagnetic systems possessing a spin-gap in their excitation spectrum. We will focus on newly discovered one-dimensional Haldane system PbNi2V2O8 as well as two-dimensional spin gap systems SrCu2(BO3)2 and Cu2WS4 (which is a candidate for a spin-gap system). In particular we will be interested in what is the impact of various perturbations in spin interactions, like for instance doping with magnetic or nonmagnetic impurities or magnetic anisotropy, on the magnitude of the spin gap, stability of the ground state as well as on the nature of the excited states. We will also study quantum phase transitions from the spin liquid to a long-range ordered antiferromagnetic states. We hope that we will be able to improve phase diagrams of these systems and to answer to some of the above questions.
We will try to dope all three systems systematically with magnetic as well as nonmagnetic impurities. The obtained samples will be structurally characterized by X-ray diffraction and neutron diffraction. To study magnetic properties we will measure static and dynamics magnetic susceptibility in different magnetic fields. On selected samples we plan to measure the magnetization curves up to very high magnetic fields in order to induce magnetic-field driven phase transitions. Magnetic resonance (NMR and EPR) will be measured in a broad temperature and frequency range. We also plan to measure EPR at very high resonant frequencies, i.e. at frequencies, which are already comparable to the magnitude of the spin-gap. Such approach will enable us to get a complete spectrum of the low-energy excited states and determination of their energy levels. We expect that the results will be of some importance for the understanding of the magnetism in low-dimensional systems as well as for the understanding of the high-temperature superconductivity in copper-oxides. Education of young scientists will also enable Slovenia to catch the contact with the World in this highly prestigious field of the physics of condensed matter.
