Magnetic properties of the Li-doped cuprates La2Cu1-xLixO4 (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 TN 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.

We report muon-spin-relaxation studies in the Li-doped cuprates (Formula presented)(Formula presented)(Formula presented)(Formula presented) for x=0.01, 0.05, 0.10, 0.45, and 0.50. For low Li concentrations (x⩽0.10) we find a rapid suppression of (Formula presented) as x increases, but little change in the magnitude and temperature dependence of the antiferromagnetic order parameter. This indicates that Li doping effectively destroys antiferromagnetism (similar to Sr doping, but different from Zn doping) without strongly affecting either the on-site Cu moments or the shape of the spin-wave excitation spectrum. For high Li concentrations we find that the majority of the sample volume is nonmagnetic, suggesting possible singlet-state formation. © 1996 The American Physical Society.

We report on muon spin rotation experiments probing the magnetic penetration depth λ(T) in the layered superconductors in 2H-NbSe₂ and 4H-NbSe₂. The current results, along with our earlier findings on 1T'-MoTe₂ (Guguchia et al.), demonstrate that the superfluid density scales linearly with T _c in the three transition metal dichalcogenide superconductors. Upon increasing pressure, we observe a substantial increase of the superfluid density in 2H-NbSe₂, which we find to correlate with T _c. The correlation deviates from the abovementioned linear trend. A similar deviation from the Uemura line was also observed in previous pressure studies of optimally doped cuprates. This correlation between the superfluid density and T _c is considered a hallmark feature of unconventional superconductivity. Here, we show that this correlation is an intrinsic property of the superconductivity in transition metal dichalcogenides, whereas the ratio T _c/T _F is approximately a factor of 20 lower than the ratio observed in hole-doped cuprates. We, furthermore, find that the values of the superconducting gaps are insensitive to the suppression of the charge density wave state.

We report muon spin rotation/relaxation (μSR) measurements of the heavy fermion superconductor UPt3 in external fields H ext∥ĉ. We find that the muon Knight shift is unchanged in the superconducting state, consistent with odd-parity pairing (such as p wave). The transverse field relaxation is observed to be strongly field dependent, decreasing with increasing field. Below Tc the increase is barely detectable in an applied field of 4 kG∥ĉ. On the basis of the high field measurements, we estimate the low temperature penetration depth to be λ(T→0)≥ (R18)11 000 Å.

We report muon spin rotation/relaxation (μSR) measurements of the heavy fermion superconductors UBe13 and UPt3. In both materials we find that the muon Knight shift is unchanged in the superconducting state, consistent with odd-parity pairing (such as p-wave). The magnetic field penetration depths in UPt3 and UBe13 are extremely long, greater than 10000 Å. We find no evidence of a magnetic transition in UBe13 below 10 K. © 1991.