4f heavy fermion photoelectron spectra do not exhibit the Kondo scale

Technical Report · Tue Feb 01 04:00:00 EST 1994

DOI:https://doi.org/10.2172/10120139· OSTI ID:10120139

Arko, A J; Joyce, J J; Andrews, A B; Blyth, R I.R.; Bartlett, R J; Fisk, Z ^[1]; Canfield, P C; Olson, C G; Benning, P J ^[2]; Poirier, D M; Weaver, J H ^[3]; Riseborough, P S ^[4]

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1. Los Alamos National Lab., NM (United States)
2. Iowa State Univ., Ames, IA (United States)
3. Univ. of Minnesota, Minneapolis, MN (United States)
4. Polytechnic Univ., Brooklyn, NY (United States)

It has been the authors contention for some time that the Single Impurity Anderson Model (SIAM), as extended by Gunnarsson and Schonhammer (GS), or the non-crossing approximation (NCA), does not correctly describe the 4f photoelectron spectra of heavy fermions. Recently, they have concentrated on Yb heavy fermions since in these materials the Kondo resonance (KR) is fully occupied and thus accessible via photoemission. In particular, they have repeatedly pointed out that the width, position, spectral weight, lineshape, and temperature dependence of the features assumed to be the KR and its sidebands, are nearly independent of the Kondo temperature, T{sub K}, while at the same time bearing a striking resemblance to the simple 4f core level spectra of pure Yb metal, or of Lu in isostructural Lu compounds. It is important to resolve these issues in view of the fundamental nature of the problem. Here, the authors chose to test the bulk vs. surface hypothesis by performing measurements on YbCu{sub 2}Si{sub 2} and YbAl{sub 3} single crystals at hv {approx} 120 eV (UPS) and hv {approx} 1,500 eV(XPS) to see if the n{sub f}, hole occupancy, values increase markedly at XPS energies as the electron escape depth increases by about a factor of 3--5. Measurements were performed at both 300K and 20K using single crystals cleaved in-situ, with photoelectrons collected in normal emission for maximum bulk sensitivity. UPS measurements were performed at NSLS and the University of Wisconsin SRC, while XPS measurements were done at the University of Minnesota. The UPS, ultraviolet photoelectron spectra, and the L{sub III} edge x-ray absorption and photoemission measurements are in fundamental disagreement.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 10120139
• Report Number(s): LA-UR--94-217; CONF-931247--1; ON: DE94006252
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104
665100
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM ALLOYS
BINARY ALLOY SYSTEMS
COPPER ALLOYS
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
KONDO EFFECT
NUCLEAR TECHNIQUES IN CONDENSED MATTER PHYSICS
PHOTOELECTRON SPECTROSCOPY
PHYSICAL PROPERTIES
SILVER ALLOYS
TERNARY ALLOY SYSTEMS
ULTRAVIOLET RADIATION
X RADIATION
YTTERBIUM ALLOYS