TY - JOUR
T1 - Crystal fields and exchange parameters in LaAl2
T2 - Eu2+ and LaAl2: Gd3+ single crystals
AU - Baberschke, K.
AU - Bachor, B.
AU - Barnes, S. E.
PY - 1980
Y1 - 1980
N2 - Reported are 10- and 35-GHz ESR measurements on single crystals of GdxLa1-xAl2 and EuxLa1-xAl2, x=100-1000 ppm. For the Gd alloys no effects of fine structure could be detected, which, under the prevalent experimental conditions implies b4<10 G. In contrast the Eu alloys exhibit a large, b4=+112 G, b6=-8 G, 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 Gd3+ scaled to Eu2+.
AB - Reported are 10- and 35-GHz ESR measurements on single crystals of GdxLa1-xAl2 and EuxLa1-xAl2, x=100-1000 ppm. For the Gd alloys no effects of fine structure could be detected, which, under the prevalent experimental conditions implies b4<10 G. In contrast the Eu alloys exhibit a large, b4=+112 G, b6=-8 G, 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 Gd3+ scaled to Eu2+.
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U2 - 10.1103/PhysRevB.21.2666
DO - 10.1103/PhysRevB.21.2666
M3 - Article
AN - SCOPUS:35949019956
VL - 21
SP - 2666
EP - 2673
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 2469-9950
IS - 7
ER -