Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 52: Superconductivity: Fe-based Superconductors – FeSe and others
TT 52.3: Vortrag
Mittwoch, 18. März 2015, 10:00–10:15, H 2053
Magnetoresistance and pressure effects on FeSe single crystals — •Stephan Knöner1, David Zielke1, Thomas Wolf2, Christoph Meingast2, and Michael Lang1 — 1Physikalisches Institut, J.W. Goethe-Universität Frankfurt(M), SPP1458, D-60438 Frankfurt(M), Germany — 2Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany
Among the various iron-based superconductors, FeSe is of special interest, because of its simple structure without spacing layers. In addition, the system exhibits a structural phase transition at ambient pressure and lacks long-range magnetic order. We present resistivity measurements on the newly synthesized FeSe single crystals under truly hydrostatic He-gas pressure up to 800 MPa and magnetic fields up to 10 T. With this technique we were able to precisely determine the pressure dependence of the superconducting (Tc) and structural transition (TS) in this pressure region, revealing linear pressure dependences with coefficients of dTS/dP = -31 K/GPa, higher than previously published results, and dTc/dP = +5.8 K/GPa, which fits very well to literature data. The resistivity just above the superconducting transition has a linear T-dependence and does not change under pressure. A positive magnetoresistance shows up for magnetic fields applied parallel to the c-axis of the crystal, whereas no effect can be observed with the field parallel to the ab-plane. This magnetoresistance grows significantly in size upon cooling through TS for all pressures. At low temperatures the size of the magnetoresistance decreases with increasing pressure.