Session B19 - Hyperfine Interactions.
MIXED session, Monday morning, March 17
Room 2206, Conv. Center
Luke S. J. Peng, Gary S. Collins (Washington State University, Pullman.)
Annealed FeRh has the ordered B2 crystal structure below 1600 K, becoming ferromagnetic below 750 K and antiferromagnetic below about 400K.(E. Navarro et al., Solid State Comm. 100, 57 (1996) and refs therein.) We report here measurements on an annealed, equiatomic sample (50.0 atomic % Fe). X-ray analysis showed that the sample has the B2 structure with a lattice parameter of 0.29869(1) nm at 293 K and no trace of any other phase. 57Fe Moessbauer effect measurements showed that the internal hyperfine field is 25.5 T at 293 K and 27.2 T at about 80 K, presumably both in the AF phase. The zero-absorber thickness extrapolated linewidth at 293 K is 0.27(1) mm/s for our source, the same as for iron-metal, indicating a very high degree of crystalline order in the annealed sample. Moessbauer measurements are planned to study point defects introduced by thermal or mechanical treatment. The defects will be detected through electric-quadrupole and magnetic field disturbances that they produce at neighboring 57Fe probes.