Magnetic Properties of Spin-Ladders (A2Cu2O3)m(CuO2)n
| Autor: | H. Szymczak, M. Baran, S. Dyeyev, L. I. Leonyuk, G.-J. Babonas, R. Szymczak |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Acta Physica Polonica A. 97:571-574 |
| ISSN: | 1898-794X 0587-4246 |
| DOI: | 10.12693/aphyspola.97.571 |
| Popis: | The investigated compounds are members of a large family (A2Cu2O3)m(CυO2)n of ladder compounds (where A positions are occupied by an alkaline earth or trivalent metal). Their orthorhombic structure contains two structural modules with the same α and b lattice parameters and different incommensurate c parameters. The modules A2Cu2Ο3 create a two-leg ladders plane between two layers of A-cations. The modules CuO2 represent the plane of weakly coupled Cu-O chains. Α different structure of both modules along the c-axis is caused by the Cu—O squares sharing the corners and edges, respectively. In the commensurate approximation the average lattice parameter along the c-axis can be expressed as c = m x cl = n x c2 (where cl and c2 are the c lattice parameters for the first and second modules, respectively). For the m/n values of 5/7, 7/10, and 9/13, it leads to chemical formulae of three known phases [1-4] of the given family: A 10 Cu17Ο29 , Α14Cu24Ο41 , and Α18Cu31Ο53, respectively. In Sr14Cu24Ο41 a dimerized singlet state has been reported [5, 6] with an energy gap between the ground and excited states. The mechanism of dimerization in such case has not been still clarified. The concentration of holes and their distribution over various sites influences significantly the magnetic properties of investigated compounds. Because the ladders in the investigated compounds are similar to those in SrCu2O3 (with an energy gap of 400-600 K [7]), their contribution to magnetic properties below room temperature can be neglected. Therefore, the magnetism |
| Databáze: | OpenAIRE |
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