Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 81: Superconductivity: Properties and Electronic Structure

TT 81.14: Vortrag

Donnerstag, 3. April 2014, 13:00–13:15, HSZ 201

Search for superconductivity in differently treated graphite powders — •Pablo Esquinazi, Annette Setzer, Jose Carlos de Moraes Silva, and Winfried Böhlmann — Division of Superconductivity and Magnetism, University of Leipzig, Leipzig, Germany

Hints on the existence of superconductivity at high temperatures were reported recently in water-treated graphite powders [1], graphite TEM lamellae [2], as well as in graphite flakes embedded in alkanes [3]. There is evidence that interfaces between graphite Bernal structure could play a role in the measured response [2,4]. In this contribution we studied the magnetic response of high purity graphite powders treated with water, alkanes as well as with acids. Background independent as well as background dependent methods were used to check for pinned magnetic entities. Clear hysteresis in temperature (between zero-field cooled and field cooled) as well as in field were measured, which survives at very high temperatures. To compare the observed behavior with that expected from ferromagnetic particles, we have also measured ferromagnetic magnetite particles embedded in amorphous carbon. We discuss the obtained evidence in terms of triggered superconductivity and/or magnetic order.
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