Torque magnetometry on single-crystal high-temperature superconductors near the critical temperature: A scaling approach
| Autor: | Hugo Keller, Thomas Schneider, K. Kishio, M. Willemin, J. Hofer, Takao Sasagawa, J. Karpinski, J. M. Singer, K. Conder |
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| Rok vydání: | 2000 |
| Předmět: |
Physics
High-temperature superconductivity Magnetic moment Condensed matter physics Magnetometer Condensed Matter - Superconductivity FOS: Physical sciences law.invention Superconductivity (cond-mat.supr-con) Effective mass (solid-state physics) law Condensed Matter::Superconductivity Cuprate Anisotropy Single crystal Scaling |
| Zdroj: | Physical Review B. 62:631-639 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.62.631 |
| Popis: | Angular-dependent magnetic torque measurements performed near the critical temperature on single crystals of HgBa_{2}CuO_{4+y}, La_{2-x}Sr{x}CuO_{4}, and YBa_{2}Cu_{3}O_{6.93} are scaled, following the 3D XY model, in order to determine the scaling function dG^{\pm}(z)/dz which describes the universal critical properties near T_{c}. A systematic shift of the scaling function with increasing effective mass anisotropy \gamma = (m_{ab}*/m_{c}*)^{1/2} is observed, which may be understood in terms of a 3D-2D crossover. Further evidence for a 3D-2D crossover is found from temperature-dependent torque measurements carried out in different magnetic fields at different field orientations \delta, which show a quasi 2D "crossing region'' (M*,T*). The occurrence of this "crossing phenomenon'' is explained in a phenomenological way from the weak z dependence of the scaling function around a value z = z*. The "crossing'' temperature T* is found to be angular-dependent. Torque measurements above T_{c} reveal that fluctuations are strongly enhanced in the underdoped regime where the anisotropy is large, whereas they are less important in the overdoped regime. Comment: 9 pages, 10 figures, submitted to PRB |
| Databáze: | OpenAIRE |
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