Commentary on the superconducting and magnetic properties of the ruthenocuprates

Abstract

Presented in this commentary is a short discussion of the superconducting and magnetic properties of selected compounds of ruthenocuprates, with an emphasis given to the RuSr 2 GdCu 2 O 8 compound. The ruthenocuprates, which form derivative class in the cuprate family, continue raising interest for there evidenced presence of magnetic ordering in the sublattice of Ru ions, which in polycrystalline samples of RuSr 2 GdCu 2 O 8 sets at T m ≈ 132 K, and at low temperatures may become simultaneous with the superconducting phase (T c,max ≈ 50 K)-all that in the crystal structure derived from well known REBa 2 Cu 3 O 7 cuprate superconductor. While several here invoked recent results advocate for an intrinsically inhomogeneous nucleation of superconductivity within this structure, the formed superconducting phase carries potential of maintaining substantial anisotropy with then interesting consequence for probing the cuprate characteristic superconductivity in these compounds. . The magnetic ordering seems to acquire an effective ferromagnetic character at the magnetic field values well below the second critical field for the superconducting phase, which put together with fact that the ordering originates in d-type electron shells of the Ru ions, which also contribute electrons to the density of states close to Fermi level, have outlined broad interest in the properties of these compounds. Since the mechanism as well as prerequisite electronic structure necessary to achieve the superconducting condensation in cuprates, especially for charge underdoped part of the class phase diagram, are still at debate, the ruthenocuprates seemed offering a promising research platform not only to approach the issue of apparent coexistence of their transition metal magnetism with superconductivity but also to extend the investigation of cuprate characteristic superconductivity to a new domain of its possible coexistence with ferromagnetism. Several years of intensive research provided us with a lot of information, however, as we learn more, a handful of questions still remain unanswered concerning very nature of complex properties of these compounds. The challenge remains to provide a compelling description of the magnetic ground state, to elucidate a role of the Klamut PMC Physics B 2010, 3:2