Crystal-field and Kondo-scale investigations ofCeMIn5(M=Co, Ir, and Rh): A combined x-ray absorption and inelastic neutr

Abstract

Linear-polarized soft-x-ray absorption ͑XAS͒ and inelastic neutron scattering ͑INS͒ experiments have been performed on CeMIn 5 with M = Rh, Ir, and Co to determine the crystal-field scheme and characteristic Kondo temperatures T ‫ء‬ 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 M 4,5 edge and the crystal-field splittings from INS. The characteristic temperature T ‫ء‬ has been determined from the line widths of the neutron scattering data. We find that the quasielastic linewidths of the superconducting compounds CeCoIn 5 and CeIrIn 5 are comparable with the low-energy crystal-field splitting.

Electronic Structures of Ferromagnetic CeAgSb2: Soft X-ray Absorption, Magnetic Circular Dichroism, and Angle-Resolved Photoemission Spectroscopies

“…It has been shown that the analysis of the LD effects using the ligand field multiplet (LFM) model gives a good quantitative description of the CEF ground state 26,[28][29][30] . In CeAgSb 2 , the CEF splitting energies from the ground state to the first and second excited states (∆ 1 and ∆ 2 ) have been determined to be 5.2 meV (≈60 K) and 12.5 meV (≈145 K) from the INS measurements, in which the CEF ground state is |±1/2 and the first and second exited levels are dominated by |±3/2 and |±5/2 , respectively 8 .…”

Avoided valence transition in a plutonium superconductor

“…It would also be interesting to explore the effects of uniaxial strain on the magnitude of elastic softening, T v , and T c . Making the crystal structure more or less tetragonal with uniaxial strain along theĉ axis should tune the 5f degeneracy (34,35) and thus, the valence fluctuations: uniaxial strain may be the tuning parameter required to reach the valence quantum critical point and may realize even higher T c values than hydrostatic pressure.…”

Exploring small energy scales with x-ray absorption and dichroism

“…Its magnetic variants, x-ray magnetic linear and circular dichroism (XMLD, XMCD) constitute sensitive element and orbital specific probes of magnetic polarization and anisotropy [15][16][17][18][19][20]. XMCD was successfully utilized to reveal the presence of magnetic Kondo screening in CePt 5 /Pt(111) [21].In the present letter we demonstrate that the combined use of linear and magnetic circular dichroism allows us to determine the crystal field structure without recourse to e. g. inelastic neutron scattering, as in some previous work [7][8][9]. Our chosen example of an ultrathin Ce-Ag surface intermetallic furthermore highlights a threefold advantage of this approach.…”

“…In the present letter we demonstrate that the combined use of linear and magnetic circular dichroism allows us to determine the crystal field structure without recourse to e. g. inelastic neutron scattering, as in some previous work [7][8][9] the same installation and therefore can be performed in situ within a single experimental run. Second, the splittings turn out to be of the order of 1 meV only, making their discrimination from quasi-elastic scattering a difficult task.…”

“…In a solid environment, the degeneracy of the rare earth 4f ground configuration is lifted by the crystal field in general, causing both an anisotropic 4f charge distribution and, in conjunction with spin orbit coupling, (single ion) magnetic anisotropy. Unraveling the crystal field induced level structure thus constitutes an essential part of understanding the low temperature physics and of establishing correlations between local 4f symmetry at low temperature on the one hand and macroscopic ground state properties on the other.In this respect, the usefulness of probing the 4f configuration with linear polarized soft x-rays [6] has been demonstrated for a variety of Ce compounds in recent years [7][8][9][10][11][12][13][14], allowing to settle several open issues, where other experiments left room for diverging interpretations. Its magnetic variants, x-ray magnetic linear and circular dichroism (XMLD, XMCD) constitute sensitive element and orbital specific probes of magnetic polarization and anisotropy [15][16][17][18][19][20].…”