Crystal fields and exchange parameters in LaAl/sub 2/: Eu/sup 2 +/ and LaAl/sub 2/: Gd/sup 3 +/ single crystals

Journal Article · Tue Apr 01 00:00:00 EST 1980 · Phys. Rev., B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.21.2666· OSTI ID:5418892

Baberschke, K; Bachor, B; Barnes, S E

Reported are 10- and 35-GHz ESR measurements on single crystals of Gd/sub x/La/sub 1-x/Al/sub 2/ and Eu/sub x/La/sub 1-x/Al/sub 2/, x=100-1000 ppm. For the Gd alloys no effects of fine structure could be detected, which, under the prevalent experimental conditions, implies b/sub 4/<10 G. In contrast the Eu alloys exhibit a large, b/sub 4/=+112 gauss, b/sub 6/=-8 gauss, crystal field, the largest in a metal to date and corresponding to an overall crystal-field splitting of 480 mK. This system is the first to show resolved fine structure and a bottleneck. A computer analysis using the full Barnes-Plefka theory shows excellent agreement between theory and experiment. As is usually the case, the exchange obtained from the g shift does not agree with that from the linewidth. We show that this cannot be explained in terms of the current ''spherically symmetric partial-wave-expansion'' approach but is reconcilable with the crystal-field split-band theory of Narath. Finally we show that, including the ferromagnetic Kondo effect, our g-shift exchange parameter is consistent with the theoretical value of Harmon and Freeman for Gd/sup 3 +/ scaled to Eu/sup 2 +/.

• Research Organization: Institut fuer Atom- und Festkoerperphysik, Freie Universitaet Berlin, Boltzmannstrasse 20, 1000 Berlin-West 33, Germany
• OSTI ID: 5418892
• Journal Information: Phys. Rev., B: Condens. Matter; (United States), Vol. 21:7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
CRYSTAL FIELD
LANTHANUM ALLOYS
CRYSTAL STRUCTURE
CRYSTAL DOPING
ELECTRON SPIN RESONANCE
EUROPIUM ADDITIONS
EXCHANGE INTERACTIONS
GADOLINIUM ADDITIONS
RARE EARTH ADDITIONS
VALENCE
ALLOYS
ALUMINIUM ALLOYS
EUROPIUM ALLOYS
GADOLINIUM ALLOYS
INTERACTIONS
MAGNETIC RESONANCE
RARE EARTH ALLOYS
RESONANCE
360102* - Metals &amp; Alloys- Structure &amp; Phase Studies