Variable temperature study of the crystal and magnetic structures of the giant magnetoresistant materials LMnAsO (L=La, Nd)

N. Emery, E. J. Wildman, J. M. S. Skakle, Abbie McLaughlin, R. I. Smith, A. N. Fitch

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Abstract

A variable temperature neutron and synchrotron diffraction study has been performed on the giant magnetoresistant oxypnictides LMnAsO (L=La, Nd). The low-temperature magnetic structures have been studied, and results show a spin reorientation of the Mn2+ spins below T-N (Nd) for NdMnAsO. The Mn2+ spins rotate from alignment along c to alignment into the basal plane, and the Mn2+ and Nd3+ moments refine to 3.54(4) mu(B) and 1.93(4) mu(B), respectively, at 2 K. In contrast, there is no change in magnetic structure with temperature for LaMnAsO. There is no evidence of a structural transition down to 2 K; however, discontinuities in the cell volume and L-O and Mn-As bond lengths are detected at similar to 150 K for both materials. This temperature coincides with the electronic transition previously reported and suggests a coupling between electronic and lattice degrees of freedom.

Original languageEnglish
Article number144429
Number of pages6
JournalPhysical Review B Condensed Matter and Materials Physics
Volume83
Issue number14
DOIs
Publication statusPublished - 29 Apr 2011

Keywords

  • Zrcusias-type-structure
  • superconductivity
  • systems
  • earth
  • metal
  • GD
  • SM

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