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Projects / Programmes source: ARIS

Study of one- and two-dimensional antiferomagnets with a spin gap

Research activity

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 
Keywords
antiferromagnets, spin gap, spin liquids, magnetic resonance
Evaluation (rules)
source: COBISS
Researchers (7)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  14080  PhD Denis Arčon  Physics  Head  2004 - 2007  597 
2.  04943  PhD Janez Bonča  Physics  Researcher  2004 - 2007  286 
3.  01106  PhD Pavel Cevc  Physics  Researcher  2004 - 2007  217 
4.  03939  PhD Janez Dolinšek  Physics  Researcher  2004 - 2007  771 
5.  11892  PhD Zvonko Jagličić  Physics  Researcher  2004 - 2007  733 
6.  18274  PhD Polona Umek  Chemistry  Researcher  2004 - 2007  329 
7.  21558  PhD Andrej Zorko  Physics  Researcher  2004 - 2007  298 
Organisations (2)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0101  Institute of Mathematics, Physics and Mechanics  Ljubljana  5055598000  20,143 
2.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,961 
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.
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