Local Magnetic Susceptibility of the Positive Muon in the Quasi 1D S=1/2 Antiferromagnet KCuF3_3

We report muon spin rotation measurements of the local magnetic susceptibility around a positive muon in the paramagnetic state of the quasi one-dimensional spin 1/2 antiferromagnet KCuF$_3$. Signals from two distinct sites are resolved which have a temperature dependent frequency shift which is different than the magnetic susceptibility. This difference is attributed to a muon induced perturbation of the spin 1/2 chain.Comment: 13 pages, 4 figures, The 2002 International Conference on Muon Spin Rotation, Relaxation and Resonance, Virginia. US

Probing magnetic order in heavily doped La2-xSrxNiO4+δ with μSR

We report μSR measurements on a series of compounds with composition La2-xSrxNiO4+δ where the net hole concentration x + 2δ is greater than 0.4. A magnetic transition is found in all the samples studied which occurs at a composition-dependent temperature TM. Below TM, clear precession signals are observed in zero applied magnetic field. The possible muon sites are discussed within the context of dipole-field calculations

Muon-spin-relaxation studies of magnetic order in heavily doped La2-xSrxNiO4+δ

We report muon-spin-relaxation measurements on a series of compounds with composition La2-xSrxNiO4+δ where the net hole concentration x+2δ is greater than 0.4. A magnetic transition is found in all the samples studied which occurs at a composition-dependent temperature TM. Below TM clear precession signals are observed in zero applied magnetic field, indicating the existence of at least short-range magnetic order on a time scale greater than 10-8 s. Above TM the correlation times decrease by several orders of magnitude. The measurements of TM as a function of the net hole concentration extend the determination of Néel temperatures by previous neutron diffraction measurements to higher doping levels