High-pressure {sup 155}Gd Moessbauer experiments on Gd intermetallic compounds compared with first-principles band-structure calculations

Journal Article · Mon Sep 01 00:00:00 EDT 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.56.5786· OSTI ID:560701

Mulder, F M ^[1]; Coehoorn, R ^[2]; Thiel, R C; Buschow, K H ^[1]

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1. Kamerlingh-Onnes Laboratory, Leiden University, P.O. Box 9506, 2300 RA Leiden (The Netherlands)
2. Philips Research Laboratories, Prof. Holstlaan 4, 5656 AA Eindhoven (The Netherlands)

High-pressure {sup 155}Gd Moessbauer measurements on Gd metal, GdCo{sub 5}, GdRu{sub 2}Si{sub 2}, and Gd{sub 2}Co{sub 17}N{sub 3} were performed at 4.2 K. The maximum pressures reached were about 18 GPa. The resulting volume reductions of 20{endash}30{percent} were determined using high-pressure x-ray diffraction. The pressure dependence of the electric-field gradients and hyperfine fields obtained for the first three systems was compared with predictions from first-principles band-structure calculations. Significant changes of the hyperfine parameters are observed, especially for elemental Gd metal. With increasing pressure, an increase of the electron density at the Gd nuclei is found in all compounds. The values of the hyperfine field initially increase with pressure. For Gd metal the induced structural phase transitions result in large changes in the electric-field gradient at the nucleus (V{sub zz}). The intermetallic compounds show no structural phase transitions and relatively small changes in V{sub zz}. The combination of experiment and calculations indicates that the transition-metal magnetic moments decrease at high pressure. Although for zero pressure predictions of the electric-field gradient and the hyperfine fields, based on the calculations, are quite accurate, the calculated pressure dependence of the hyperfine parameters for Gd, GdCo{sub 5}, and GdRu{sub 2}Si{sub 2} does not in all cases lead to a satisfactory agreement with experiment. The application of pressures therefore may give additional stimulus for the improvement of the theoretical description of band structures and hyperfine parameters. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 560701
• Journal Information: Physical Review, B: Condensed Matter, Vol. 56, Issue 10; Other Information: PBD: Sep 1997
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
GADOLINIUM 155
MOESSBAUER EFFECT
GADOLINIUM ALLOYS
ELECTRONIC STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
COBALT ALLOYS
RUTHENIUM ALLOYS
SILICON ALLOYS
NITROGEN COMPOUNDS
INTERMETALLIC COMPOUNDS
X-RAY DIFFRACTION
ELECTRON DENSITY
MAGNETIC MOMENTS
TEMPERATURE RANGE 0000-0013 K