Japanese Journal of Applied Physics · 1987 · 66 citations · 9 references
Natural SciencesMaterials SciencePhysicsCondensed Matter PhysicsSolid State PhysicsSpectroscopyMagnetic AnisotropyMagnetic OxidesMagnetic Properties Of SolidsMagnetism In SolidsMössbauer SpectroscopyPhase TransitionsAnisotropySpin StatesStability Of Magnetic IslandsTemperature-dependent Mössbauer SpectroscopyTransition Metal Magnetism
YBa2Cu3Oy doped with 57Fe (Cu/Fe = 99/1, Tc(ρ = 0) = 88 K for y = 6.86) has been studied by Mössbauer spectroscopy. The state of Fe has been assigned to Fe3+ with S=3/2. The site preferentially occupied by Fe3+, and probably by Cu3+, changes from Cu(2) for y<6.8 to Cu(1) for y>6.8; i.e. as the Cu(1)-O-Cu(1) chain structure approaches completion, and the vibrational anisotropy is enhanced at the same time. For y = 6.0, a phase transition leading to a disproportionation into high and intermediate spin states has been observed in the magnetic spectra below 30 K. The spectrum for y = 6.86 at 1.5 K suggests formation of magnetic islands around Fe.
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