Magnetic order near the (001) surface of UO_2: An x-ray scattering study.
Abstract
We have used glancing-incidence x-ray scattering to study the magnetic ordering near the (001) surface of UO2 for temperatures from 10 to 35 K. These measurements were performed with the incident photon energy tuned to the U M_IV absorption edge at 3.728 keV at which there is a significant enhancement in the magnetic scattering cross section. In the bulk, UO2 is a type-I antiferromagnet which undergoes a discontinuous ordering transition at TN = 30.2 K. In contrast, we find that for an x-ray penetration depth of approximately 50 Åthe magnetic order parameter appears continuous and is well described by a power law in reduced temperature, I = A*t^2*β, where t = (T-T_N)/T_N. These results are reminiscent of the superlattice ordering observed in near-surface studies of Cu_3Au (See, for example, H. Dosch et al.), Phys. Rev. B 43, 13172 (1991).; however, preliminary results obtained at various locations along the magnetic truncation rod suggest that a different mechanism may govern the ordering near the UO2 surface. Work at Brookhaven is supported by the USDOE under Contract No. DE-AC02-76CH00016.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR.S2211W