https://doi.org/10.1140/epjb/e2007-00149-8
Magnetotransport of lanthanum doped RuSr2GdCu2O8 – the role of gadolinium
1
Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 331, 10002 Zagreb, Croatia
2
2. Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany
3
Industrial Research, P.O. Box 31310, Lower Hutt, New Zealand
Corresponding author: a mpozek@phy.hr
Received:
20
December
2006
Revised:
27
April
2007
Published online:
25
May
2007
Strongly underdoped RuSr1.9La0.1GdCu2O8 has been comprehensively studied by dc magnetization, microwave measurements, magnetoresistivity and Hall resistivity in fields up to 9 T and temperatures down to 1.75 K. Electron doping by La reduces the hole concentration in the CuO2 planes and completely suppresses superconductivity. Microwave absorption, dc resistivity and ordinary Hall effect data indicate that the carrier concentration is reduced and a semiconductor-like temperature dependence is observed. Two magnetic ordering transitions are observed. The ruthenium sublattice orders antiferromagnetically at 155 K in low applied magnetic fields, and the gadolinium sublattice orders antiferromagnetically at 2.8 K. The magnetoresistivity in this compound exhibits a complicated temperature dependence due to the occurence of the two magnetic orders and spin fluctuations. It is shown that the ruthenium magnetism influences the conductivity in the RuO2 layers while the gadolinium magnetism influences the conductivity in the CuO2 layers. The magnetoresistivity is isotropic above 4 K, but it becomes anisotropic close to the gadolinium antiferromagnetic order temperature.
PACS: 74.72.-h – Cuprate superconductors / 74.25.Fy – Transport properties / 74.25.Ha – Magnetic properties / 74.25.Nf – Response to electromagnetic fields
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007