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We investigate the Néel temperature of Sr 2 CuO 3 as a function of the site dilution at the Cu ͑S =1/2͒ sites with Pd ͑S =0͒, utilizing the muon spin relaxation ͑SR͒ technique. The Néel temperature, which is T N = 5.4 K for the undoped system, becomes significantly reduced for less than one percent of doping Pd, giving a support for the previous proposal for the good one-dimensionality. The Pd concentration dependence of the Néel temperature is compared with a recent theoretical study [S. Eggert, I. Affleck, and M. D. P. Horton, Phys. Rev. Lett. 89, 47 202 (2002)] of weakly coupled one-dimensional antiferromagnetic chains of S =1/2 spins, and a quantitative agreement is found. The inhomogeneity of the ordered moment sizes is characterized by the SR time spectra. We propose a model that the ordered moment size recovers away from the dopant S = 0 sites with a recovery length of Ϸ 150− 200 sites. The origin of the finite recovery length for the gapless S =1/2 antiferromagnetic chain is compared to the estimate based on the effective staggered magnetic field from the neighboring chains.

Muon spin relaxation and magnetic susceptibility measurements have been performed on the pure and diluted spin 1/2 kagomé system (CuxZn(1-x))3V2O7(OH)2 2H2O. In the pure x=1 system we found a slowing down of Cu spin fluctuations with decreasing temperature towards T approximately 1 K, followed by slow and nearly temperature-independent spin fluctuations persisting down to T=50 mK, indicative of quantum fluctuations. No indication of static spin freezing was detected in either of the pure (x=1.0) or diluted samples. The observed magnitude of fluctuating fields indicates that the slow spin fluctuations represent an intrinsic property of kagomé network rather than impurity spins.

We report muon spin relaxation (µSR) and magnetization measurements, together with synthesis and characterization, of the Li-intercalated layered superconductors Li x HfNCl and Li x ZrNCl with/without co-intercalation of THF

Muon spin relaxation (µSR) measurements in high transverse magnetic fields ( ĉ) revealed strong field-induced quasi-static magnetism in the underdoped and Eu doped (La,Sr)2CuO4 and La1.875Ba0.125CuO4, existing well above Tc and TN . The susceptibility-counterpart of Cu spin polarization, derived from the muon spin relaxation rate, exhibits a divergent behavior towards T ∼ 25 K. No field-induced magnetism was detected in overdoped La1.81Sr0.19CuO4, optimally doped Bi2212, and Zn-doped YBa2Cu3O7.