Field-dependent anomalies in the thermodynamic and transport properties of RuSr2GdCu2O8—Evidence for a spin-flop transition

• Published in: The Journal of physics and chemistry of solids Vol. 73; no. 11; pp. 1290 - 1295
• Main Authors: McCrone, J.E., Cooper, J.R., Loram, J.W., Tallon, J.L.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2012
• Subjects: A. Superconductors; B. Epitaxial growth; Ceramics; D. Electrical properties; D. Magnetic properties; D. Specific heat; Ferromagnetism; Magnetic fields; Magnetic permeability; Magnetization; Neutron diffraction; Superconductivity; Thin films; D. Magnetic properties; A. Superconductors; D. Specific heat; B. Epitaxial growth; D. Electrical properties
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2012.06.001

Thermopower and magnetization studies of epitaxial thin films and sintered polycrystalline ceramics of RuSr2GdCu2O8 show evidence for the occurrence of a spin-flop transition, consistent with earlier neutron diffraction data. Realignment of spins in a magnetic field enhances Tc by up to 4K, presumably due to reduced magnetic pair-breaking. Specific heat and powder AC susceptibility measurements give strong evidence for bulk superconductivity. High temperature magnetization measurements indicate in-plane ferromagnetic correlations which remain to be reconciled with low-temperature neutron diffraction evidence for conventional G-type antiferromagnetism. ► Single crystal films of RuSr2GdCu2O8 (Ru:1212) were prepared and their hole content measured. ► Thin film magnetizable and polycrystalline TEP data give evidence for a spin-flop transition. ► The ruthenium ions interact ferromagnetically above their magnetic ordering temperature. ► The superconducting transition temperature Tc is increased from 38 to 42K by fields of a few Tesla. ► Our observations are consistent with a spontaneous vortex state below Tc in zero applied field.