RuthenocupratesRuSr2(Eu,Ce)2

Abstract

We report ac susceptibility data on RuSr2(Eu,Ce)2Cu2O10−y (Ru-1222, Ce content x=0.5 and 1.0), RuSr2GdCu2O8 (Ru-1212) and SrRuO3. Both Ru-1222 (x=0.5, 1.0) sample types exhibit unexpected magnetic dynamics in low magnetic fields: logarithmic time relaxation, switching behavior, and 'inverted' hysteresis loops. Neither Ru-1212 nor SrRuO3 exhibit such magnetic dynamics. The results are interpreted as evidence of the complex magnetic order in Ru-1222. We propose a specific multilayer model to explain the data, and note that superconductivity in the ruthenocuprate is compatible with both the presence and absence of the magnetic dynamics.

The ruthenocuprates: natural superconductor–ferromagnet multilayers

“…Further, complex time dependent phenomena were found in dc or ac magnetic susceptibility measurements [64,60,65,66,67], pointing perhaps to a spin glass behavior even at low temperatures, caused by the presence of oxygen vacancies in the RuO6 octahedra [65,66,67]. In [64] the interesting conclusion has been drawn that the complex behavior could be due to an antiparallel ordering of the in-plane magnetizations of adjacent RuO2 layers. Then, similar to the case of the type I ordering proposed for Ru-1212 by Butera et al [44] also Ru-1222 could exhibit an intrinsic spin valve effect in case there is an interlayer tunnel transport in this material.…”

“…Alternatively, the transition could be due the presence of nanoparticles of a foreign minor extra Ru 4+ magnetic phase of Sr-Cu-Ru-O3 in which Cu is distributed inhomogeneously in both the Ru and Sr sites [63]. Further, complex time dependent phenomena were found in dc or ac magnetic susceptibility measurements [64,60,65,66,67], pointing perhaps to a spin glass behavior even at low temperatures, caused by the presence of oxygen vacancies in the RuO6 octahedra [65,66,67]. In [64] the interesting conclusion has been drawn that the complex behavior could be due to an antiparallel ordering of the in-plane magnetizations of adjacent RuO2 layers.…”

Magnetoresistance hysteresis and critical current density in granularRuSr2Gd2−xFelner1, Galstyan2, Lorenz3 et al. 2003Phys. Rev. BSelf Cite5412230View full textAdd to dashboardCite

“…The microstructure of Ru-1222 (xϭ0.5) exhibits well-defined grains with a typical size of 1-2 m and pronounced grain boundaries. 16 The transport transition to the SC state occurs via two intermediate stages. 17 The intragrain sharp drop of the resistivity at T C occurs when the grains become superconducting.…”

Magneto-Superconductivity of Rutheno-Cuprates

“…This gets credence from the fact, that though Ln = Y sample unlike others contains small impurity of SrRuO 3 , the 150 K transition in fc is same for all the studied compounds. In widely studied Gd/Ru-1222 compound also the rise in FC magnetization is reported at around 160-180 K, and was associated with an antiferromagnetic transition of Ru spins [7,27,34]. We did couple of M vs H experiments for Ln = Ho sample at various temperatures of 130, 120, 110, 100 and 5 K, the results are shown in Fig.29 (a, b, c, d and e).…”