Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 20: Metall-Isolator-Überg
änge
TT 20.2: Vortrag
Mittwoch, 10. März 2004, 14:45–15:00, H18
Weak ferromagnetism of the charge stripes in La5/3Sr1/3NiO4 — •Rüdiger Klingeler1, Bernd Büchner1, Sang-Wook Cheong2, and Markus Hücker3 — 1Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, PF 27 01 16, 01171 Dresden — 2Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 — 3Physics Department, Brookhaven National Laboratory, Upton, New York 11973
In doped nickelates the interplay of charge and spin degrees of freedom results a long range charge order where static charge stripes and spin stripes are present. We present measurements of the high field magnetization and the specific heat of a La5/3Sr1/3NiO4 single crystal in order to elucidate the thermodynamic properties of the stripe phase. The data provide the magnetic phase diagram. The charge ordering temperature TCO is nearly independent of the magnetic field and there is a significant and highly anisotropic field dependence of the long range spin ordering temperature TSO. High field magnetization data reveals a weak ferromagnetism in the entire stripe ordered phase. We analyze these data in terms of weak moments which are long range correlated. Double exchange interactions are discussed as a possible origin of the weak ferromagnetism.