Static magnetic correlations near the insulating-superconducting phase boundary in La2-xSrxCuO4

Comparison of the high-frequency magnetic fluctuations in insulating and superconducting La2-xSrxCuO4.

Inelastic neutron scattering performed at a spallation source is used to make absolute measurements of the dynamic susceptibility of insulating La2CuO4 and superconducting La1.86Sr0.14CuO4 over the energy range 15 ≤ h̄ω ≤ 350 meV. The effect of Sr doping on the magnetic excitations is to cause a large broadening in wavevector and a substantial change in the spectrum of the local spin fluctuation...

New Magnetic Coherence Effect in Superconducting La2-xSrxCuO4.

Magnetic order in lightly doped La2-xSrxCuO4.

We study long wavelength magnetic excitations in lightly doped La2-xSrxCuO4 (x</=0.03) detwinned crystals. The lowest energy magnetic anisotropy induced gap can be understood in terms of the antisymmetric spin interaction inside the antiferromagnetic (AF) phase. The second magnetic resonance, analyzed in terms of in-plane spin anisotropy, shows unconventional behavior within the AF state; it le...

Josephson plasmon and inhomogeneous superconducting state in La2-xSrxCuO4.

We report on the interlayer far infrared response for a series of La2-xSrxCuO4 crystals with 0.08<x<0.20 focusing on the survey of the Josephson plasmon resonance (JPR). The analysis of the JPR mode provides information on the local variation of the superfluid density within the CuO2 planes thus empowering one with a tool for "microscopy" on the superconducting condensate. Our results uncover t...

Magnetic–Field Induced Localization in the Normal State of Superconducting La2−xSrxCuO4

Magnetoresistance measurements of highly underdoped superconducting La2−xSrxCuO4 films with x = 0.051 and x = 0.048, performed in dc magnetic fields up to 20 T and at temperatures down to 40 mK, reveal a magnetic–field induced transition from weak to strong localization in the normal state. The normal–state conductances per CuO2–plane, measured at different fields in a single specimen, are foun...