A Variable Temperature Synchrotron X-ray Diffraction Study of Colossal Magnetoresistant NdMnAsO0.95F0.05

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Abstract

The recent discovery of high temperature superconductivity in Fe arsenides has invigorated research into transition metal pnictides. Colossal magnetoresistance (CMR) has recently been reported for NdMnAsO1-xFx for x = 0.05–0.08, with a maximum magnetoresistance achieved at low temperature (MR9T(3 K)) = −95%). This appears to be a novel mechanism of CMR, which is as a result of a second order phase transition in field from an insulating antiferromagnet to a semiconducting paramagnet. Here we report a variable temperature synchrotron X-ray powder diffraction study of the CMR oxypnictide NdMnAsO0.95F0.05 between 4 K–290 K. An excellent fit to the tetragonal unit cell with space group P4/nmm is obtained over the entire temperature range, with no change in crystal structure detected down to 4 K. A coupling of the lattice and magnetic order is observed, where subtle discontinuities in the temperature variation of a and the c/a ratio are apparent as the Nd spins order antiferromagnetically and the Mn moments reorient into the basal plane at TSR. The results suggest that very small changes in lattice parameters effect the coupling between lattice, electronic and magnetic degrees of freedom.
Original languageEnglish
Article number20705
Pages (from-to)1-7
Number of pages7
JournalScientific Reports
Volume6
DOIs
Publication statusPublished - 15 Feb 2016

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synchrotrons
diffraction
arsenides
Group 5A compounds
x rays
temperature
lattice parameters
discontinuity
superconductivity
degrees of freedom
transition metals
moments
crystal structure
cells
electronics

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@article{273fd4b69c764771b67313303214d228,
title = "A Variable Temperature Synchrotron X-ray Diffraction Study of Colossal Magnetoresistant NdMnAsO0.95F0.05",
abstract = "The recent discovery of high temperature superconductivity in Fe arsenides has invigorated research into transition metal pnictides. Colossal magnetoresistance (CMR) has recently been reported for NdMnAsO1-xFx for x = 0.05–0.08, with a maximum magnetoresistance achieved at low temperature (MR9T(3 K)) = −95{\%}). This appears to be a novel mechanism of CMR, which is as a result of a second order phase transition in field from an insulating antiferromagnet to a semiconducting paramagnet. Here we report a variable temperature synchrotron X-ray powder diffraction study of the CMR oxypnictide NdMnAsO0.95F0.05 between 4 K–290 K. An excellent fit to the tetragonal unit cell with space group P4/nmm is obtained over the entire temperature range, with no change in crystal structure detected down to 4 K. A coupling of the lattice and magnetic order is observed, where subtle discontinuities in the temperature variation of a and the c/a ratio are apparent as the Nd spins order antiferromagnetically and the Mn moments reorient into the basal plane at TSR. The results suggest that very small changes in lattice parameters effect the coupling between lattice, electronic and magnetic degrees of freedom.",
author = "Wildman, {E. J.} and McLaughlin, {A. C.}",
note = "This research was supported by the EPSRC (EP/L002493/1). We also acknowledge STFC-GB for provision of beamtime at the ESRF.",
year = "2016",
month = "2",
day = "15",
doi = "10.1038/srep20705",
language = "English",
volume = "6",
pages = "1--7",
journal = "Scientific Reports",
issn = "2045-2322",
publisher = "Nature Publishing Group",

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TY - JOUR

T1 - A Variable Temperature Synchrotron X-ray Diffraction Study of Colossal Magnetoresistant NdMnAsO0.95F0.05

AU - Wildman, E. J.

AU - McLaughlin, A. C.

N1 - This research was supported by the EPSRC (EP/L002493/1). We also acknowledge STFC-GB for provision of beamtime at the ESRF.

PY - 2016/2/15

Y1 - 2016/2/15

N2 - The recent discovery of high temperature superconductivity in Fe arsenides has invigorated research into transition metal pnictides. Colossal magnetoresistance (CMR) has recently been reported for NdMnAsO1-xFx for x = 0.05–0.08, with a maximum magnetoresistance achieved at low temperature (MR9T(3 K)) = −95%). This appears to be a novel mechanism of CMR, which is as a result of a second order phase transition in field from an insulating antiferromagnet to a semiconducting paramagnet. Here we report a variable temperature synchrotron X-ray powder diffraction study of the CMR oxypnictide NdMnAsO0.95F0.05 between 4 K–290 K. An excellent fit to the tetragonal unit cell with space group P4/nmm is obtained over the entire temperature range, with no change in crystal structure detected down to 4 K. A coupling of the lattice and magnetic order is observed, where subtle discontinuities in the temperature variation of a and the c/a ratio are apparent as the Nd spins order antiferromagnetically and the Mn moments reorient into the basal plane at TSR. The results suggest that very small changes in lattice parameters effect the coupling between lattice, electronic and magnetic degrees of freedom.

AB - The recent discovery of high temperature superconductivity in Fe arsenides has invigorated research into transition metal pnictides. Colossal magnetoresistance (CMR) has recently been reported for NdMnAsO1-xFx for x = 0.05–0.08, with a maximum magnetoresistance achieved at low temperature (MR9T(3 K)) = −95%). This appears to be a novel mechanism of CMR, which is as a result of a second order phase transition in field from an insulating antiferromagnet to a semiconducting paramagnet. Here we report a variable temperature synchrotron X-ray powder diffraction study of the CMR oxypnictide NdMnAsO0.95F0.05 between 4 K–290 K. An excellent fit to the tetragonal unit cell with space group P4/nmm is obtained over the entire temperature range, with no change in crystal structure detected down to 4 K. A coupling of the lattice and magnetic order is observed, where subtle discontinuities in the temperature variation of a and the c/a ratio are apparent as the Nd spins order antiferromagnetically and the Mn moments reorient into the basal plane at TSR. The results suggest that very small changes in lattice parameters effect the coupling between lattice, electronic and magnetic degrees of freedom.

U2 - 10.1038/srep20705

DO - 10.1038/srep20705

M3 - Article

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JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

M1 - 20705

ER -