[en] Magnetic properties of single crystal Ba₂Cu₃O₄Cl₂ with Cu₃O₄ planes were investigated by temperature- and magnetic-field-dependent anisotropic magnetization M(T,H) and zero-field-μSR. Muon spin precession was observed below as well as above T=32 K where an anomaly in M(T) appears. At this temperature the frequency of the precession changes and the damping of it diverges. This is an evidence for a magnetic transition. We also found the temperature dependence of the H-linear component of M(H) shows a maximum around T=80 K, which is similar to the behavior of low-dimensional magnets with an antiferromagnetic interaction

[en] A discontinuous change of muon-spin precession frequencies in CaV₃O₇ is observed at T∼0.2 K, indicating a possible spin reorientation. Our results suggest that CaV₃O₇ possesses the identical spin direction as isostructural SrV₃O₇ below ∼0.2 K, although the spin directions in the two compounds are different at higher temperatures as determined by elastic neutron scattering

[en] Muon spin relaxation (μ⁺SR) measurements of CsC₆₀ and RbC₆₀ have revealed magnetic ordering at 20 K and 15 K respectively, with static internal fields at the muon site of ∼7 G for both samples. No magnetic ordering is seen in KC₆₀ down to 2.5 K. An apparent small increase in muon spin relaxation which had been seen at 70 K in RbC₆₀ is ascribed to an extrinsic effect, originating in muons which stopped in the aluminum sample holder

[en] We present μSR experiments on La_2-x Ba_x CuO₄ and La_1.6-x Nd_0.4 Sr_x CuO₄ for x=0.125. Both of these materials order magnetically with T_N ∼ 30 K, while a superconducting sample of La_1.4 Nd_0.4 Sr_0.2 CuO₄ showed no evidence for static copper moments. Our results support the conclusion that the so-called '1/8' anomaly in La_2-x Ba_x CuO₄ is a result of static (pinned) charge segregation

[en] We report the muon spin rotation experiments on Zn substituted La_1-x Sr_x CuO₄, for four zinc concentrations y=0.0,0.0025,0.005,0.01, at strontium concentrations x=0.15,0.20. We find that T_c in the optimally doped (x=0.15) and overdoped (x=0.20) 2:1:4 decreases linearly with increasing zinc concentration. Plotted against the planar zinc concentration, the T_c's of both series seem to fall on the same line. The superconducting carrier density/effective mass ratio, n_s/m*, at first decreases linearly, rising above this line for higher zinc concentrations. This behavior may result from the localization of carriers in an area ξ_ab around each zinc atom

[en] Muon spin relaxation was measured down to 0.05 K on a geometrically frustrated metallic system, β-Mn. The observed relaxation rate increases with decreasing temperature and unexpectedly makes a peak at 0.5 K indicating a spin freezing below the temperature. Actually the asymmetry is almost recovered by applying a longitudinal magnetic field of 0.1 T. But since the tail amplitude is more than half and the dynamical relaxation is still appreciable at the lowest temperature, it is likely that the frozen moments are associated with imperfection as oxygen impurity and the intrinsic ground state is fluctuating spin liquid

[en] Zero-field μ⁺SR and resistivity experiments on La_0.67Ca_0.33MnO₃ powder show that the ferromagnetic transition temperature (T_C=274 K) and resistivity peak temperature coincide to within 1 K, about 10 K higher than T_C determined from the bulk magnetization. The sublattice magnetization ν_μ(T) is well described for T ≤ T_C by (1-T/T_C)^β , where β =0.345 ± 0.015. Unusual relaxation dynamics suggest a wide distribution of Mn-ion correlation times. These results are discussed in terms of the effects of polarons on the spin and charge dynamics

[en] We have performed transverse-field muon spin relaxation measurements of the Zn-substituted cuprate high-T_c superconductors: La_2-xSr_x(Cu_1-yZn_y)O₄ and YBa₂(Cu_1-yZn_y)₃O_6.63. The superconducting carrier density/effective mass n_s/m^* ratio at T→0 decreases with increasing Zn concentration, in a manner consistent with our open-quote open-quote swiss cheese close-quote close-quote model in which charge carriers within an area πξ_ab² around each Zn are excluded from the superfluid. We discuss this result in the context of Bose condensation, pair localization, and pair breaking. copyright 1996 The American Physical Society

[en] We present the results of μSR measurements of the transverse field relaxation rate below T_c for seven samples of HgBa₂ CuO_4+δ, spanning the underdoped, optimally doped, and nominally overdoped regions of the superconducting phase. On comparison with the 'anomalous' thermopower data for these compounds, we find that nominally 'overdoped' Hg 1:2:0:1 resembles underdoped compounds in certain respects

[en] Magnetic properties of the Li-doped cuprates La₂Cu_1-xLi_xO₄ (where x=0.01,0.05,0.10,0.45, and 0.50) have been studied by μSR. For low Li concentrations (x ≤ 0.10) we find a rapid suppression of T_N as x increases, but little change in the magnitude and temperature dependence of the AFM order parameter. This indicates that Li doping effectively destroys AFM (similar to Sr doping, but different from Zn doping) without strongly affecting the onsite Cu moments and the shape of the spinwave excitation spectrum. For high Li concentrations we find magnetic clusters in about 15% of the sample volume; the remaining volume is non-magnetic, suggesting possible singlet-state formation