Charge and spin states of Ru and Cu in magnetic superconductor RuSr2GdCu2O8 studied by NMR

Ken-ichi Kumagai; Satomi Takada; Yuji Furukawa

doi:10.1103/PhysRevB.63.180509

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Charge and spin states of Ru and Cu in magnetic superconductor RuSr2GdCu2O8 studied by NMR

Ken-ichi Kumagai, Satomi Takada, Yuji Furukawa

DOI 10.1103/PhysRevB.63.180509 · Physical Review B

T1

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Abstract

Electronic and magnetic properties of RuSr2GdCu2O8 have been investigated by electric resistivity, magnetization, and Cu-, Ru-NMR measurements. Magnetic order (TM=133 K) and superconductivity [Ts(onset)∼52 K] have been confirmed. We observed two kinds of Ru-NMR signals (the hyperfine fields of 101Ru are 590 kOe and 290 kOe), suggesting a charge segregation of Ru5+ (S=3/2) and Ru4+ (S=1) in the RuO2 layers. The hyperfine field at the Cu site is diminishingly small, indicating magnetic interactions between CuO2 and RuO2 layers are weak. Assuming that holes are inherently doped in the CuO2 layers from the (Ru4+, Ru5+)O2 layers, the high-Tc superconductivity can occur under weak magnetic interactions between Ru and Cu spins in RuSr2GdCu2O8.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
RuSr2GdCu2O8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	52	Pressure not reported	onset
RuSr2GdCu2O8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	34	Pressure not reported	zero_resistance
Sr2RuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.5	Pressure not reported	unknown