Neutron scattering investigation of magnetic phase transitions and crystal-field splitting in $UX_{3}$(X identical to Br, Cl)

Content Provider	Scilit
Author	Schmid, B. Murasik, A. Fischer, P. Furrer, A. Kanellakopulos, B.
Copyright Year	1990
Description	Journal: Journal of Physics: Condensed Matter Neutron scattering experiments were performed in the temperature range from 1.5 to 293 K on polycrystalline samples of the non-metallic $5f^{3}$ electron systems $UBr_{3}$ and $UCl_{3}$. The hexagonal crystal structure $P6_{3}$/m was refined at T=293 and 10 K. $UBr_{3}$ orders at $T_{N}$=5.4(1) K with a second-order transition to a 0+-configuration of magnetic moments of magnitude mu _{U}$^{(3.9K)}$=2.08(2) mu$ _{B}$ oriented parallel to the c axis. At $T_{t}$=3.0(5) K occurs a second transition to an ordered antiferromagnetic ground state, corresponding to the lattice constants $a_{m}$= square root 3a, $b_{m}$=a, $c_{m}$=2a. This structure is anticentered in the basal plane. The magnetic moments of magnitude mu _{U}$^{(1.6K)}$=0.82(4) mu$ _{B}$ are oriented parallel to the b axis. In both magnetic phases the antitranslation (0, 0,$ $^{1}$/_{2}$) suggests predominantly antiferromagnetic exchange within the chains of uranium ions along the c axis. The situation is similar for $UCl_{3}$: the first transition at $T_{N}$=6.5(1) K with an ordered magnetic moment mu _{U}$^{(4.0K)}$ of 1.8(1) mu$ _{B}$, and the second transition at $T_{t}$=3.8(5) K with a magnetic moment mu _{U}$^{(1.6K)}$ of 0.8(1) mu$ _{B}$. By means of inelastic neutron scattering the authors have measured the crystal-field splitting of $UBr_{3}$ and $UCl_{3}$ and determined the crystal-field parameters. The assumption of anisotropic magnetic interactions reasonably predicts the value of the zero-field magnetisation and provides an explanation for the magnetic phase transitions.
Related Links	http://iopscience.iop.org/article/10.1088/0953-8984/2/14/021/pdf
Ending Page	3380
Page Count	12
Starting Page	3369
ISSN	09538984
e-ISSN	1361648X
DOI	10.1088/0953-8984/2/14/021
Journal	Journal of Physics: Condensed Matter
Issue Number	14
Volume Number	2
Language	English
Publisher	IOP Publishing
Publisher Date	1990-04-09
Access Restriction	Open
Subject Keyword	Journal: Journal of Physics: Condensed Matter Second Order Magnetic Moment Neutron Scattering Ground State Crystal Structure Inelastic Neutron Scattering
Content Type	Text
Resource Type	Article
Subject	Condensed Matter Physics Materials Science