Magnetic Ordering and Frustration in Hexagonal U<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Ni</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span>B

S. A. M. Mentink; A. Drost; G. J. Nieuwenhuys; E. Frikkee; A. A. Menovsky; J. A. Mydosh

doi:10.1103/PhysRevLett.73.1031

Magnetic Ordering and Frustration in Hexagonal U ${Ni}_{4}$ B

S. A. M. Mentink, A. Drost, G. J. Nieuwenhuys, E. Frikkee, A. A. Menovsky, and J. A. Mydosh

Phys. Rev. Lett. 73, 1031 – Published 15 August 1994

Abstract

We have determined unusual magnetic ordering of the hexagonal intermetallic uranium compound U $N_{i 4}$ B via neutron diffraction. In the easy basal plane the U moments have triangular symmetry with antiferromagnetic interactions. Along the hard $c$ axis ferromagnetic coupling occurs. Below $T_{N} = 20$ K only two out of every three U moments of $1.2 μ_{B}$ order in vortexlike arrangements around the third paramagnetic spin. This novel magnetic structure is related to the occurrence of a crystallographic superstructure. Previously observed anomalies in bulk properties below $T_{N}$ are attributed to unconventional spin-wave excitations associated with this type of ordering.

Received 3 May 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.1031

Authors & Affiliations

S. A. M. Mentink¹, A. Drost², G. J. Nieuwenhuys¹, E. Frikkee², A. A. Menovsky¹, and J. A. Mydosh¹

¹Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9506, 2300 RA Leiden, The Netherlands
²Netherlands Energy Research Foundation ECN, P.O. Box 1, 1755 ZG Petten, The Netherlands