An intriguing magnetodielectric behavior is observed in triangular or tetrahedral frustrated and low-dimensional system. Therefore, the spin-tetrahedral and low-dimensional compound copper-tellurides (Cu2Te2O5Br2) is suggested that has magnetodielectric behavior. Tetragonal Cu2Te2O5Br2 contains clusters of four Cu2+ (S = 1/2) in a planar coordination. These tetrahedral form weakly coupled sheets within the crystallographic a-b plane. Therefore, this system is ideal to study the interplay between the spin frustration on a tetrahedron with localized low-energy excitations and collective magnetism induced by inter-tetrahedral couplings. In this material a strongly reduced magnetic transition temperature To = 11.5 K in comparison with a dominant magnetic exchange of 30 K is found. Low-dimensional systems with triangular geometries are considered as prominent candidates for applications using novel magnetoelectric materials. At the highest applied magnetic field 90 kOe, the temperature dependent dielectric behavior with almost frequency independent well defined maxima at Tm ~ 30 K and To ~ 11.5 K are enhanced compared with that at zero field. We suggest that the observed magnetodielectric coupling can arise from exchange striction involving frustrated tetramer clusters and inter-cluster exchange bridges with polarizable lone-pair electrons on Te4+ ions.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0722111-165907 |
| Date | 22 July 2011 |
| Creators | Chin, Yi-Pin |
| Contributors | Hsiung Chou, Hung-Duen Yang, Jiunn-Yuan Lin, Yung-Sung Chen |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0722111-165907 |
| Rights | withheld, Copyright information available at source archive |
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