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Title: Lattice disorder and size-induced Kondo behavior in CeAl2 andCePt2+x

Abstract

When the particle size of CeAl{sub 2} and CePt{sub 2+x} samples is reduced to the nanometer scale, antiferromagnetism is suppressed and Kondo behavior dominates. We find that the Kondo temperature T{sub K} can either decrease (CeAl{sub 2}) or increase (CePt{sub 2+x}) in the nanoparticles relative to the bulk. Extended x-ray absorption fine-structure data show that the Ce-Al and Ce-Pt environments are significantly distorted in the nanoparticles. While such distortions should strongly affect magnetic and electronic properties, we find they cannot explain the observed changes in T{sub K}. Changes in the conduction density of states or other parameters must, therefore, play a significant role.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director. Office of Science. Office of AdvancedScientific Computing Research. Office of Basic EnergySciences
OSTI Identifier:
894233
Report Number(s):
LBNL-59846
Journal ID: ISSN 0031-9007; PRLTAO; R&D Project: 365723; TRN: US0700105
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 97; Related Information: Journal Publication Date: 2006
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ANTIFERROMAGNETISM; FINE STRUCTURE; PARTICLE SIZE

Citation Formats

Han, S.-W., Booth, C.H., Bauer, E.D., Huang P.H., Chen, Y.Y., and Lawrence, J.M. Lattice disorder and size-induced Kondo behavior in CeAl2 andCePt2+x. United States: N. p., 2006. Web. doi:10.1103/PhysRevLett.97.097204.
Han, S.-W., Booth, C.H., Bauer, E.D., Huang P.H., Chen, Y.Y., & Lawrence, J.M. Lattice disorder and size-induced Kondo behavior in CeAl2 andCePt2+x. United States. doi:10.1103/PhysRevLett.97.097204.
Han, S.-W., Booth, C.H., Bauer, E.D., Huang P.H., Chen, Y.Y., and Lawrence, J.M. Tue . "Lattice disorder and size-induced Kondo behavior in CeAl2 andCePt2+x". United States. doi:10.1103/PhysRevLett.97.097204. https://www.osti.gov/servlets/purl/894233.
@article{osti_894233,
title = {Lattice disorder and size-induced Kondo behavior in CeAl2 andCePt2+x},
author = {Han, S.-W. and Booth, C.H. and Bauer, E.D. and Huang P.H. and Chen, Y.Y. and Lawrence, J.M.},
abstractNote = {When the particle size of CeAl{sub 2} and CePt{sub 2+x} samples is reduced to the nanometer scale, antiferromagnetism is suppressed and Kondo behavior dominates. We find that the Kondo temperature T{sub K} can either decrease (CeAl{sub 2}) or increase (CePt{sub 2+x}) in the nanoparticles relative to the bulk. Extended x-ray absorption fine-structure data show that the Ce-Al and Ce-Pt environments are significantly distorted in the nanoparticles. While such distortions should strongly affect magnetic and electronic properties, we find they cannot explain the observed changes in T{sub K}. Changes in the conduction density of states or other parameters must, therefore, play a significant role.},
doi = {10.1103/PhysRevLett.97.097204},
journal = {Physical Review Letters},
number = ,
volume = 97,
place = {United States},
year = {Tue Mar 14 00:00:00 EST 2006},
month = {Tue Mar 14 00:00:00 EST 2006}
}
  • When the particle size of CeAl{sub 2} and CePt{sub 2+x} samples is reduced to the nanometer scale, antiferromagnetism is suppressed and Kondo behavior dominates. We find that the Kondo temperature T{sub K} can either decrease (CeAl{sub 2}) or increase (CePt{sub 2+x}) in the nanoparticles relative to the bulk. Extended x-ray absorption fine-structure data show that the Ce-Al and Ce-Pt environments are significantly distorted in the nanoparticles. While such distortions should strongly affect magnetic and electronic properties, we find they cannot explain the observed changes in T{sub K}. Changes in the conduction density of states or other parameters must, therefore, playmore » a significant role.« less
  • When the size of CeAl{sub 2} and CePt{sub 2+x} particles is reduced to the nanometer scale, antiferromagnetism is suppressed and Kondo behavior predominates, with the Kondo temperature T{sub K} either decreasing (CeAl{sub 2}) or increasing (CePt{sub 2+x}) relative to the bulk. Local structure measurements show that these nanoparticles are significantly distorted. While such distortions should strongly affect magnetic and electronic properties, we find they cannot explain the observed changes in T{sub K}. Other size-induced changes to the electronic structure must, therefore, play a significant role.
  • Muon spin rotation ({mu}SR) has been used to probe non-Fermi-liquid (NFL) behavior in the heavy-fermion alloys UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}, {ital x}=1.0 and 1.5, and CeCu{sub 5.9}Au{sub 0.1}. Zero-field {mu}SR puts an upper bound of {approximately}0.01{mu}{sub {ital B}}/{ital U} atom on any static magnetism in UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}, which is too weak to affect the transverse-field {mu}SR linewidth or to give rise to NFL behavior. In agreement with NMR results, {mu}SR spectra in transverse fields suggest that a broad distribution of Kondo temperatures ({open_quote}{open_quote}Kondo disorder{close_quote}{close_quote}) is important in UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}. NFL anomalies at temperaturemore » {ital T} then arise from {open_quote}{open_quote}free{close_quote}{close_quote} spins for which {ital T}{sub {ital K}}{lt}{ital T}. Comparison of {mu}SR and NMR linewidths also indicates short-range spatial correlation of the Kondo disorder in UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}, in agreement with the local character of the dynamic susceptibility inferred from neutron scattering experiments. In CeCu{sub 5.9}Au{sub 0.1} the data suggest significant Kondo disorder only if the spatial correlation is long ranged, which is not indicated by other properties of this alloy. {copyright} {ital 1996 The American Physical Society.}« less
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