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R G Goodrich

Publications and source records attributed to R G Goodrich.

6 recordsLinked to original sources
PubMed2006

Fermi surface changes across the Néel phase boundary of NdB6.

We report de Haas-van Alphen measurements in both the antiferromagetic and paramagnetic regimes of NdB6, which are shown to be separated by a second order upper critical field for antiferromagnetic ordering of H_{c} approximately 30 T when the magnetic field is parallel to [001]. The Fermi surface changes across the transition provide an ideal example of a system in which the effect of a one-dimensional magnetic periodic potential on doubling the unit cell (as originally predicted by Slater [Phys. Rev. 82, 538 (1951)]) can be tuned by varying only the magnetic field. The Fermi surface within the paramagnetic phase resembles that observed in other hexaborides such as LaB6 but with additional exchange splitting effects and weak correlations.

Journal Article↗
PubMed2004

4f-electron localization in CexLa 1-xM In5 with M=Co, Rh, or Ir.

de Haas-van Alphen measurements on Ce(x)La(1-x)MIn(5) yield contrasting types of behavior that depend on whether M=Co and Ir or M=Rh. A stronger x-dependent scattering in the case of M=Co and Ir is suggestive of a stronger relative coupling, J/W, of the conduction electrons to the 4f electrons, which would then account for the development of a heavy composite Fermi-liquid state as x-->1. The failure of a composite Fermi-liquid state to form for any x in the case of M= Rh is shown to be inconsistent with theoretical models that propose antiferromagnetism to result from spin-density-wave formation.

Journal Article↗
PubMed2004

Electron-spin domains: magnetic enhancement of superconductivity.

An inhomogeneous superconducting state, not yet conclusively identified, was predicted by Fulde and Ferrell and Larkin and Ovchinnikov (FFLO) to arise in superconductors with strong Pauli limiting, a consequence of the electrons' Zeeman (spin) energy in a magnetic field. Radovan et al. propose that the observed cascades of steps in magnetization of the heavy fermion superconductor CeCoIn5, within the recently discovered second low-temperature state, are due to transitions between Landau-level (LL) states with different m-quanta vortices, expected under certain conditions when the magnetic field is swept within the FFLO state. The authors then conclude that the observed steps in magnetization constitute a proof that the low-temperature state in CeCoIn5 is indeed an FFLO state. We argue that this interpretation of the observed steps in magnetization cannot be supported on either quantitative or qualitative grounds.

Comment↗
PubMed2002

Magnetization in the ultraquantum limit.

The magnetization below and far above the quantum limit for small Fermi surface orbits has been measured in the metallic compound LaRhIn(5). The magnetization due to a pocket of Fermi surface that comprises less than 1 part in 10(4) of the total Brillouin zone volume, and for which the quantum limit is approximately 7 T, leads to the appearance of an overall sample magnetic moment at fields between 7 and 32 T. This moment arises from diamagnetic currents produced by electrons in the ultraquantum limit. A model calculation of the origin and magnitude of the effect is in excellent agreement with the measured field dependence of the induced magnetization.

Journal Article↗