Nuclear spin driven quantum relaxation in LiY_0.998Ho_0.002F_4

Staircase hysteresis loops of the magnetization of a LiY_0.998Ho_0.002F_4 single crystal are observed at subkelvin temperatures and low field sweep rates. This behavior results from quantum dynamics at avoided level crossings of the energy spectrum of single Ho^{3+} ions in the presence of hyperfine interactions. Enhanced quantum relaxation in constant transverse fields allows the study of the relative magnitude of tunnel splittings. At faster sweep rates, non-equilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps.Comment: 5 pages, 5 eps figures, using RevTe

MÖSSBAUER STUDIES OF 155Tb SOURCES PRODUCED BY RECOIL IMPLANTATION IN IRON AND NICKEL

No abstract availabl

Code generation for sta architecture

Abstract. This paper presents a novel compiler backend which generates assembly code for Synchronous Transfer Architecture (STA). STA is a Very Long Instruction Word (VLIW) architecture and in addition it uses a non-orthogonal Instruction Set Architecture (ISA). Generating efficient code for this architecture needs highly optimizing techniques. The compiler backend presented in this paper is based on Integer Linear Programming (ILP). Experimental results show that the generated assembly code consumes much less execution time than the code generated by traditional ways, and the code generation can be accomplished in acceptable time.

Magnetic Ordering in CoCl₂·2P(C₆H₅)₃ and CoBr₂·2P(C₆H₅)₃

The crystal structures of CoCl2·2P(C6H5)3 and CoBr2·2P(C6H5)3 are reported. Both crystals belong to the space group P2/c with Z = 2: for the chloride, a = 11.764 (2) Å, b = 8.250 (3) Å, c = 17.254 (7) Å, and β = 106.57 (4)°; for the isostructural bromide, a = 11.828 (2) Å, b = 8.325 (2) Å, c = 17.365 (5) Å, and β = 106.58 (3)°. The crystal susceptibilities of the compounds have been measured over the temperature interval 40 mK-4 K. Antiferromagnetic ordering is observed at 0.21 ± 0.01 K (Cl) and 0.25 ± 0.01 K (Br). The specific heats have also been measured, and the ordering has been confirmed. Both compounds order with lattice dimensionality between 1 and 2, and all the data may be fit by a theoretical calculation for the rectangular Ising lattice, with Jx/Jy = 0.31 ± 0.02 for the chloride and 0.10 ± 0.02 for the bromide. These results require that the |±3/2) component of the 4A2 level be the ground state in both systems. © 1982 American Chemical Society

Low Temperature Magnetic Properties of the Bimetallic Compounds [Co(C₅H₅NO)₆](MX₄) (M = Co²⁺, Zn²⁺; X = Cl⁻, Br⁻)

We have measured the specific heat and suceptibility of the compounds [Co(C5H5NO)6] (MX4) (M = Co, Zn; X = Cl, Br), which are all isostructural and monoclinic. The data show that two magnetic subsystems are present in the Co/Co compounds. The Co2+ ions on the octahedral positions of the chlorine compounds exhibit antiferromagnetic ordering at Tc = 0.95(1) K, the Co2+ ions on the tetrahedral positions remaining paramagnetic down to at least 0.04 K. The paramagnetic ions appear to experience two different molecular fields from the ordered Co2+ ions. The behaviour of the bromine compounds is similar, the ordering temperature being about 0.65 K. Both chlorine compounds are apparently canted antiferromagnets. The bromine compounds show compensated antiferromagnetism. © 1984