Gerald D. Morris

Field Induced Reduction of the Low-Temperature Superfluid Density in YBa{sub 2}Cu{sub 3}O{sub 6.95}

A novel high magnetic field (8 T) spectrometer for muon spin rotation has been used to measure the temperature dependence of the in-plane magnetic penetration depth {lambda}{sub ab} in YBa{sub 2}Cu {sub 3}O{sub 6.95} . At low H and low T , {lambda}{sub ab} exhibits the characteristic linear T dependence associated with the energy gap of a d{sub x{sup 2}-y{sup 2}}-wave superconductor. However, at higher fields {lambda}{sub ab} is essentially temperature independent at low T . We discuss possible interpretations of this surprising new feature in the low-energy excitation spectrum. (c) 1999 The American Physical Society.

β-NMR of isolated lithium in nearly ferromagnetic palladium

The temperature dependence of the frequency shift and spin-lattice relaxation rate of isolated, nonmagnetic (8)Li impurities implanted in a nearly ferromagnetic host (Pd) are measured by means of beta-detected nuclear magnetic resonance (beta-NMR). The shift is negative, very large, and increases monotonically with decreasing T in proportion to the bulk susceptibility of Pd for T > T* approximately 100 K. Below T*, an additional shift occurs which we attribute to the response of Pd to the defect. The relaxation rate is much slower than expected for the large shift and is linear with T below T*, showing no sign of additional relaxation mechanisms associated with the defect.

Static magnetic order in metallic K0.49CoO2.

By means of muon-spin spectroscopy, we have found that K0.49CoO2 crystals undergo successive magnetic transitions from a high-T paramagnetic state to a magnetic ordered state below 60 K and then to a second ordered state below 16 K, even though K0.49CoO2 is metallic at least down to 4 K. An isotropic magnetic behavior and wide internal-field distributions suggest the formation of a commensurate helical spin density wave (SDW) state below 16 K, while a linear SDW state is likely to exist above 16 K. It was also found that exhibits a further transition at 150 K presumably due to a change in the spin state of the Co ions. Since the dependence of the internal-field below 60 K was similar to that for Na0.5CoO2, this suggests that magnetic order is more strongly affected by the Co valence than by the interlayer distance or interaction and/or the charge ordering.

β‑NMR Measurements of Lithium Ion Transport in Thin Films of Pure and Lithium-Salt-Doped Poly(ethylene oxide)

β-Detected nuclear spin relaxation of (8)Li(+) has been used to study the microscopic diffusion of lithium ions in thin films of poly(ethylene oxide) (PEO), where the implanted lithium ions are present in extremely low concentration, and PEO with 30 wt % LiCF3SO3 over a wide range of temperatures both above and below the glass transition temperature. Recent measurements by Do et al. [Phys. Rev. Lett. 2013, 111, 018301] found that the temperature dependence of the Li(+) conductivity was identical to that of the dielectric α relaxation and was well described by the Vogel-Fulcher-Tammann relation, implying the α relaxation dominates the Li(+) transport process. In contrast, we find the hopping of Li(+) in both samples in the high temperature viscoelastic phase follows an Arrhenius law and depends significantly on the salt content. We propose that the hopping of Li(+) between cages involves motion of the polymer but that it is only for long-range diffusion where the α relaxation plays an important role.

Nuclear electric quadrupole moment of 9Li using zero-field β-detected NQR

A ?-detected nuclear quadrupole resonance (NQR) spectrometer becomes a powerful tool to study changes in nuclear ground-state properties along isotopic chains when coupled to a laser excitation beamline to polarize the nuclei of interest. Recently, the ?-NQR technique in a zero magnetic field has been applied for the first time to measure the ratio of static nuclear quadrupole moments of 8, 9Li, Q9/Q8 = 0.966?75(9) denoted by Q8 for 8Li and Q9 for 9Li, respectively. This shows agreement with present literature values but with significantly improved precision. Based on the literature, the quadrupole moment for 8Li has been re-evaluated to be |Q8| = 32.6(5)?mb. From this, the quadrupole moment for 9Li is calculated as |Q9| = 31.5(5)?mb with the error being dominated by the error of Q8.

Penetration depth, multiband superconductivity, and absence of muon-induced perturbation in superconducting PrOs4Sb12

Transverse-field muon spin rotation

Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

(\text{TF-}\ensuremath{\mu}\text{SR})

Magnetic penetration depths in Y2Ba4Cu6+nO14+n−δ and local-pair condensation

experiments in the heavy-fermion superconductor

Discovery of slow magnetic fluctuations and critical slowing down in the pseudogap phase of YBa2Cu3Oy

{\text{PrOs}}_{4}{\text{Sb}}_{12}({T}_{c}=1.85\text{ }\text{K})

8Li+ β-NMR in the Cubic Insulator MgO

suggest that the superconducting penetration depth