Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Postersession Superconductivity: Materials - Fabrication and Properties

TT 5.9: Poster

Montag, 23. März 2009, 13:00–16:45, P1A

Angular dependence of the upper critical field H_c2 for CeCu₂Si₂ — •Hugo A. Vieyra¹, Niels Oeschler¹, Jeevan S. Hirale^1,2, Christoph Geibel¹, and Frank Steglich¹ — ¹Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany — ²I. Physik. Institut, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany

Unconventional superconductivity is one of the most important and fascinating topics within solid state physics. It plays a major role in the study of high-T_c and heavy-fermion superconductors. Nevertheless, the underlying physical mechanism of unconventional superconductivity is still not completely understood. A clear example of this paradigm is CeCu₂Si₂, the first unconventional superconductor discovered almost three decades ago. Angular dependent measurements have already proven to be powerful techniques to study the properties of the unconventional superconducting state. In this work, we present angular-dependent resistivity measurements on single-crystalline CeCu₂Si₂ samples with antiferromagnetic order below 800 mK and a superconducting transition around 600 mK. From the angular dependence of the upper critical field H_c2, no anisotropy is observed within the basal plane, whereas a large anisotropy is observed when the magnetic field rotates out of plane (H//a) towards the crystallographic c-axis (H//c). As the angular dependence deviates from the prediction based on the anisotropic mass model, strong Pauli paramagnetic limiting seems to dominate the upper critical field at low temperatures.