[en] Muon spin relaxation measurements have been performed in the optimally doped La_1.85-yEu_ySr_0.15CuO₄, where the static spin stripes are stabilized by the rare-earth doping. Zero-field measurements indicate that the volume fraction V_Cu of static magnetism increases with increasing Eu concentration, while the ordered moment size remains constant. Transverse-field measurements show that n_s/m^* (superconducting carrier density/effective mass) at T→0 is proportional to the non-magnetic volume fraction (1-V_Cu). These results indicate that superconductivity and static stripe magnetism occur in different spatial regions, exclusively, suggestive of microscopic phase separation

[en] We have performed detailed measurements to characterize the superconducting (T_c∼1.1 K) state of (TMTSF)₂ClO₄ using both normal and deuterated samples. Using ZF-μSR measurements to search for spontaneous magnetic fields below T_c, we see no evidence for such fields within our resolution, thus we conclude the time reversal symmetry is likely not broken. We have also performed precession measurements in the vortex state of (TMTSF)₂ClO₄. The superconducting relaxation rate decreases strongly with increasing field, which may indicate a dimensional crossover in the nature of the vortex lattice. We estimate that the penetration depth is roughly 535 nm

[en] Muon spin relaxation measurements have been performed in the two dimensional spin system SrCu₂(BO₃)₂. As the temperature decreases, the relaxation rate increases below T=10 K, and shows a saturation below T=3 K. The line shape at low temperatures is nearly Gaussian, yet it cannot be easily decoupled by an application of longitudinal field. These results indicate the existence of magnetically active spins that show slowing down of fluctuations with decreasing temperatures, yet remain dynamic even at 0.1 K. We have also examined a sample doped with small amount of non-magnetic Zn²⁺ impurity, Sr(Cu_0.99Zn_0.01)₂(BO₃)₂. The result was quite similar to the pure sample. Thus, anomalous behavior of the pure sample observed in low temperatures is not due to magnetic moments induced by impurities or a lattice defect

[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] Zero-field (ZF) and transverse-field (TF) μSR measurements have been performed on a superconducting La₂CuO_4+y crystal with y=0.12 where excess oxygen is intercalated to form a stage-4 structure. Measurements are made on the same single-crystal sample studied in the neutron scattering measurements of Lee et al. [Phys. Rev. B 60 (1999) 3643] who find that both superconductivity and static incommensurate magnetic modulation develop below $\text{T}{}_{\mathrm{<mtext>c</mtext>}}\text{∼T}{}_{\mathrm{<mtext>N</mtext>}}\text{∼42}\text{K}$. The amplitude of the muon precession signal observed in ZF-μSR increases progressively below T_N and saturates at T→0 to the value which indicates that a static magnetic field from Cu moments exists in only a part of muon sites corresponding to a magnetic site fraction of V_M=41%. The observed frequency ∼3.5 MHz of the precession signal suggests the development of a large (at least $\text{0.4}\text{μ}{}_{\mathrm{<mtext>B</mtext>}}$) static Cu moment near the “magnetic” muon sites. Comparing the TF-μSR results with computer simulations, we obtained V_M(T→0)=42%.