A possible crypto-superconducting structure in a superconducting ferromagnet

Abstract

We have measured the dc and ac electrical and magnetic properties in various magnetic fields of the recently reported superconducting ferromagnet RuSr 2 GdCu 2 O 8 . Our reversible magnetization measurements demonstrate the absence of a bulk Meissner state in the compound below the superconducting transition temperature. Several scenarios that might account for the absence of a bulk Meissner state, including the possible presence of a spongelike non-uniform superconducting or a crypto-superconducting structure in the chemically uniform Ru-1212, have been proposed and discussed.

Experimental study of the magnetosuperconductorRuSr2Eu1.5Ce0.5Cu2Awana1, Lal2, Kishan3 et al. 2006Phys. Rev. B142110View full textAdd to dashboardCite

“…Respective indices are shown in the figure. As far as pristine x = 0.0 is concerned, very small amounts of SrRuO 3 and/or GdSr 2 RuO 6 are seen close to main intensity peaks which had earlier been noted by other workers also [7,11,12,16]. Our currently studied samples are in fact, far better in terms of their phase purity as compared to those reported earlier by various authors.…”

“…Some workers have also considered the possibility of phase separation, i.e., isolated superconducting and magnetic regions within the same compound [12][13][14][15].…”

Magneto-superconductivity of 100-atm O2-annealed RuSr2Gd1.5Ce0.5Cu2O10−δ

“…The appearance of bulk superconductivity at low temperatures in Ru-1212 was initially criticised [11] which was later refuted [12,13]. Also not all single phase Ru-1212 exhibit the co-existence of superconductivity and magnetism [14].…”

Superconductivity, intragrain penetration depth, and Meissner effect ofRuSr2(Gd,Ce)2Xue1, Lorenz2, Baikalov3 et al. 2002Phys. Rev. BSelf Cite283331View full textAdd to dashboardCite

“…16 holes/CuO 2 ) or the competition between the SC and the coexisting FM through the Fulde-FerrellLarkin-Ovchinnikov ͑FFLO͒ phase. [1][2][3][4][5] A verification was difficult until the recent reports that the transition temperatures T c of Ru1222 and Ru1212 can be adjusted over a broad range by oxygen annealing and Cu substitution, respectively. [6][7][8] The reported data, unfortunately, show that the T c enhancement is accompanied by both a p increase and a suppression of the ferromagnetic spin order and offer no clear distinction.…”