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Stuttgart, Germany

Willers T.,University of Cologne | Hu Z.,University of Cologne | Hu Z.,Max Planck Institute CPfS | Hollmann N.,University of Cologne | And 17 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

Linear-polarized soft-x-ray absorption (XAS) and inelastic neutron scattering (INS) experiments have been performed on CeM In5 with M=Rh, Ir, and Co to determine the crystal-field scheme and characteristic Kondo temperatures Tz.ast; for the hybridization between 4f and conduction electrons. The ground-state wave functions are determined from the polarization-dependent soft-XAS data at the cerium M4,5 edge and the crystal-field splittings from INS. The characteristic temperature Tz.ast; has been determined from the line widths of the neutron scattering data. We find that the quasielastic linewidths of the superconducting compounds CeCoIn5 and CeIrIn5 are comparable with the low-energy crystal-field splitting. © 2010 The American Physical Society. Source


Bhattacharyya A.,Rutherford Appleton Laboratory | Bhattacharyya A.,University of Johannesburg | Khalyavin D.D.,Rutherford Appleton Laboratory | Kruger F.,Rutherford Appleton Laboratory | And 7 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2016

The newly discovered Ising-type ferromagnet CeRu2Al2B exhibits an additional phase transition at TN=14.2 K before entering the ferromagnetic ground state at TC=12.8 K. We clarify the nature of this transition through high resolution neutron diffraction measurements. The data reveal the presence of a longitudinal incommensurate spin-density wave (SDW) in the temperature range of TC Source


Gold C.,University of Augsburg | Gross P.,University of Augsburg | Peyker L.,University of Augsburg | Eickerling G.,University of Augsburg | And 6 more authors.
Journal of Physics Condensed Matter | Year: 2012

The pseudo-ternary solid solution CeNi 9Ge 4-xSi x (0≤x≤4) has been investigated by means of x-ray diffraction, magnetic susceptibility, specific heat, electrical resistivity, thermopower and inelastic neutron scattering studies. The isoelectronic substitution of germanium by silicon atoms causes a dramatic change of the relative strength of competing Kondo, RKKY and crystal field (CF) energy scales. The strongest effect is the continuous elevation of the Kondo temperature T K from approximately 3.5K for CeNi 9Ge 4 to about 70K for CeNi 9Si 4. This increase of the Kondo temperature is attended by a change of the CF level scheme of the Ce ions. The interplay of the different energy scales results in an incipient reduction of the ground state degeneracy from an effectively fourfold degenerate non-magnetic Kondo ground state with unusual non-Fermi-liquid features of CeNi 9Ge 4 to a lower one, followed by an increase towards a sixfold, fully degenerate ground state multiplet in CeNi 9Si 4 (T K∼Δ CF). © 2012 IOP Publishing Ltd. Source


Severing A.,University of Cologne | Givord F.,CEA Grenoble | Boucherle J.-X.,CEA Grenoble | Willers T.,University of Cologne | And 8 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The magnetic form factor of YbInNi4 has been determined via the flipping ratios R with polarized neutron diffraction, and the scattering function S(Q,ω) was measured in an inelastic neutron scattering experiment. Both experiments were performed with the aim of determining the crystal-field scheme. The magnetic form factor clearly excludes the possibility of a Γ7 doublet as the ground state. The inelastic neutron data exhibit two almost equally strong peaks at 3.2 meV and 4.4 meV which points, in agreement with earlier neutron data, toward a Γ8 quartet ground state. Further possibilities such as a quasiquartet ground state are discussed. © 2011 American Physical Society. Source


Bhattacharyya A.,Rutherford Appleton Laboratory | Bhattacharyya A.,University of Johannesburg | Ritter C.,Laue Langevin Institute | Adroja D.T.,Rutherford Appleton Laboratory | And 4 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2016

The magnetic state of the tetragonal compound Ce2PdGe3, which crystallizes in the space group P42/mmc, a derivative of the α-ThSi2 structure, has been investigated by magnetic susceptibility, heat capacity, muon spin relaxation (μSR), and neutron diffraction measurements. Heat capacity data indicate two separate magnetic phase transitions at TN1=10.7 K and TN2=2.3 K. The presence of bulk long-range magnetic order is confirmed by our μSR study below 11 K, where a drop of nearly 2/3 in the muon initial asymmetry and a sharp increase in the muon depolarization rate were observed. Neutron powder diffraction reveals that only one out of two Ce sites becomes magnetically ordered with magnetic propagation vector κ=(0) at TN1, adopting an antiferromagnetic arrangement of magnetic moments μCe3+=1.78(1)μB along the c axis. At TN2 the second Ce site orders similarly, following the same magnetic propagation vector κ=(0), showing, however, at the same time a significant ferromagnetic component within the tetragonal basal plane. A second propagation vector, κ=12,0,12, appears concomitantly at TN2 © 2016 American Physical Society. Source

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