On the relationship between crystal structure and magnetism in U{sub 2}Pd{sub 2}Sn and U{sub 2}Ni{sub 2}In (abstract)
- MLNSC, Los Alamos National Laboratory, Los Alamos, New Mexico 874545 (United States)
- Charles University, 12116 Prague 2, (Czech Republic)
- European Commission, ITU, 76125 Karlsruhe (Germany)
Isostructural U{sub 2}T{sub 2}X compounds (T=transmission metal, X={ital p}-electron element) offer a new perspective on the relationship between magnetic anisotropy and the geometrical arrangement of the elements, because two approximately equal shortest interuranium distances are found. The moment arrangement in magnetically ordered U{sub 2}T{sub 2}X compounds is extremely sensitive to the choice of the constituents. In order to get a deeper understanding of what finally determines the moment configuration in U{sub 2}T{sub 2}X compounds, we have studied two members of this large family, namely U{sub 2}Ni{sub 2}In and U{sub 2}Pd{sub 2}Sn. Both compounds have the shortest U{endash}U links along the {ital c} axis and order antiferromagnetically at low temperatures. The exchange coupling along the shortest U{endash}U link is antiferromagnetic in U{sub 2}Ni{sub 2}In, while it is ferromagnetic in U{sub 2}Pd{sub 2}Sn, though both compounds exhibit a noncollinear in-plane configuration of the U moments. Here, we present the results of our neutron-diffraction studies performed at various temperatures between 12 and 300 K, for temperatures above and below T{sub N}. Our analysis reveals that neither U{sub 2}Ni{sub 2}In nor U{sub 2}Pd{sub 2}Sn exhibit {open_quotes}normal{close_quotes} thermal-expansion behavior (linear contraction of the lattice with decreasing temperature). However, while deviations from the normal behavior in U{sub 2}Pd{sub 2}Sn occur only below T{sub N} (and may be attributed to magnetically driven distortions of the crystal lattice), unusual thermal expansion for U{sub 2}Ni{sub 2}In is found already at temperatures far above T{sub N}. We discuss, whether the unusual thermal expansion in U{sub 2}Ni{sub 2}In supports the formation of long-range magnetic order or whether short-range magnetic fluctuations above T{sub N} are responsible for the expansion behavior in this compound. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 580681
- Report Number(s):
- CONF-961141-; ISSN 0021-8979; TRN: 98:004229
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 8; Conference: 41. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 12-15 Nov 1996; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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