Synthesis and characterization of two metallic spin-glass phases of Fe Mo4 Ge3

Prior, Timothy; Baker, Peter J.; Battle, Peter D.; Blundell, Stephen J.; Grandjean, Fernande; Lancaster, Tom; Long, Gary J.; Oldham, Sophie E.; Prior, Timothy J.

Abstract

Polycrystalline samples of Fe Mo4 Ge3 have been synthesized by the reduction of an oxide mixture at 1248 K and characterized by a combination of diffraction, muon spin relaxation (μ+ SR), Mössbauer spectroscopy, magnetometry, transport, and heat-capacity measurements. The compound adopts a tetragonal W5 Si3 structure (space group I4 mcm); the iron and molybdenum atoms are disordered over two crystallographic sites, 16k and either 4a or 4b. The synthesis conditions determine which fourfold site is selected; occupation of either leads to the presence of one-dimensional chains of transition metals in the structure. In both cases, the electrical resistivity below 200 K is ∼175 μΩ cm. The dc magnetization rapidly rises below 35 K (Fe Mo on 16k and 4b sites) or 16 K (16k and 4a sites), and a magnetization of 1 μB or 0.8 μB per Fe atom is observed in 4 T at 2 K. The ac susceptibility and the heat capacity both suggest that these are glasslike magnetic transitions, although the transition shows a more complex temperature dependence (with two maxima in χ″) when the 4b sites are partially occupied by iron. No long-range magnetic order is thought to be present at 5 K in either structural form; this has been proven by neutron diffraction and μ+ SR for the case when Fe and Mo occupy the 16k and 4b sites. © 2008 The American Physical Society.

Citation

Baker, P. J., Battle, P. D., Blundell, S. J., Grandjean, F., Lancaster, T., Long, G. J., Oldham, S. E., & Prior, T. J. (2008). Synthesis and characterization of two metallic spin-glass phases of Fe Mo4 Ge3. Physical review B: Condensed matter and materials physics, 77(13), 134405-1 - 134405-13. https://doi.org/10.1103/physrevb.77.134405

• Journal Article Type: Article
• Online Publication Date: Apr 2, 2008
• Publication Date: Apr 1, 2008
• Journal: PHYSICAL REVIEW B
• Print ISSN: 1098-0121
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 77
• Issue: 13
• Pages: 134405-1 - 134405-13
• DOI: https://doi.org/10.1103/physrevb.77.134405
• Keywords: heat-capacity crystal-structure temperature relaxation refinement transition mo5ge3 mo5si3 muons field
• Public URL: https://hull-repository.worktribe.com/output/405220
• Publisher URL: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.77.134405