Josephson Plasma in RuSr2GdCu2O8

H. Shibata

doi:10.1103/PhysRevB.65.180507

paper

Josephson Plasma in RuSr2GdCu2O8

arXiv:cond-mat/0204070 · doi:10.1103/PhysRevB.65.180507

Abstract

Josephson plasma in RuSr $_{2}$ GdCu $_{2}$ O $_{8}$ , Ru $_{1 - x}$ Sr $_{2}$ GdCu $_{2 + x}$ O $_{8}$ (x = 0.3), and RuSr $_{2}$ Eu $_{2 - x}$ Ce $_{x}$ Cu $_{2}$ O $_{10}$ (x = 0.5) compounds is investigated by the sphere resonance method. The Josephson plasma is observed in a low-frequency region (around 8.5 cm $^{- 1}$ at T $≪$ $T_{c}$ ) for ferromagnetic RuSr $_{2}$ GdCu $_{2}$ O $_{8}$ , while it increases to 35 cm $^{- 1}$ for non-ferromagnetic Ru $_{1 - x}$ Sr $_{2}$ GdCu $_{2 + x}$ O $_{8}$ (x = 0.3), which represents a large reduction in the Josephson coupling at ferromagnetic RuO $_{2}$ block layers. The temperature dependence of the plasma does not shift to zero frequency ({\it i.e.} $j_{c}$ = 0) at low temperatures, indicating that there is no transition from the 0-phase to the $π$ -phase in these compounds. The temperature dependence and the oscillator strength of the peak are different from those of other non-magnetic cuprates, and the origins of these anomalies are discussed.

to appear in Phys. Rev.B Rapid Comm

Josephson Plasma in RuSr2GdCu2O8

Abstract

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