Biomedical subjects

C R Wiebe

Publications and source records attributed to C R Wiebe.

4 recordsLinked to original sources

PubMed2005

Muon spin relaxation studies of magnetic-field-induced effects in high-Tc superconductors.

Muon spin relaxation measurements in high transverse magnetic fields [FORMULA: SEE TEXT] revealed strong field-induced quasistatic 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 approximately 25 K. No field-induced magnetism was detected in overdoped La1.81Sr0.19CuO4, optimally doped Bi2212, and Zn-doped YBa2Cu3O7.

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PubMed2004

Magnetic ordering in the spin-ice candidate Ho2Ru2O7.

Neutron scattering measurements on the spin-ice candidate material Ho2Ru2O7 have revealed two magnetic transitions at T approximately 95 and approximately 1.4 K to long-range ordered states involving the Ru and Ho sublattices, respectively. Between these transitions, the Ho3+ moments form short-ranged ordered spin clusters. The internal field provided by the ordered S=1 Ru4+ moments disrupts the fragile spin-ice state and drives the Ho3+ moments to order. We have directly measured a slight shift in the Ho3+ crystal field levels at 95 K from the Ru ordering.

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PubMed2003

Superconductivity and field-induced magnetism in Pr2-xCexCuO4 single crystals.

We report muon-spin rotation and relaxation (muSR) measurements on single crystals of the electron-doped high-T(c) superconductor Pr2-xCexCuO4. In a zero external magnetic field, superconductivity is found to coexist with dilute Cu spins that are static on the muSR time scale. In an applied field, we observe a mu(+)-Knight shift that is primarily due to the magnetic moment induced on the Pr ions. Below the superconducting transition temperature T(c), an additional source of local magnetic field appears throughout the volume of the sample. This finding is shown to be consistent with field-induced antiferromagnetic ordering of the Cu spins. Measurements of the temperature dependence of the in-plane magnetic penetration depth lambda(ab) in the vortex state are also presented.

Journal Article↗

PubMed2003

Field dependence of the muon spin relaxation rate in MnSi.

Muon spin rotation/relaxation measurements have been performed in the itinerant helical magnet MnSi at ambient pressure and at 8.3 kbar. We have found the following: (a) the spin-lattice relaxation rate 1/T(1) shows divergence as T1T proportional, variant (T-T(c))(beta) with the power beta larger than 1 near T(c); (b) 1/T(1) is strongly reduced in an applied external field B(L) and the divergent behavior near T(c) is completely suppressed at B(L)> or =4000 G. We discuss that (a) is consistent with the self-consistent renormalization theory and reflects a departure from "mean-field" behavior, while (b) indicates selective suppression of spin fluctuations of the q=0 component by B(L).

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