The suppression of CMR in Nd(Mn1−xCox)AsO0.95F0.05

E. J. Wildman, K. S. McCombie, G. B. G. Stenning, A. C. McLaughlin (Corresponding Author)

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Abstract

The colossal magnetoresistance (CMR) observed in the oxypnictide NdMnAsO1−xFx has been further investigated. The magnetotransport is dominated by magnetopolarons. Magnetoresistance measurements of the series Nd(Mn1−xCox)AsO0.95F0.05 show that doping with cobalt on the manganese site pins the magnetopolarons and suppresses the CMR, which is completely destroyed by x = 0.047. The chemical doping results in non-stoichiometric samples, with both As and O vacancies. The relationship between the non-stoichiometry, magnetic order, electron doping and CMR is explored. The Nd antiferromagnetic transition and simultaneous reorientation of the Mn spins into the basal plane at 23 K (TSR) is not effected by Co doping. However, there is a significant decrease in TN(Mn) as the antiferromagnetic transition is suppressed from 360 K to 300 K as x increases from 0–0.047. The manganese moment at 10 K is also reduced from 3.86(2)μB to 3.21(2)μB over the same doping range. This reduction in the in-plane Mn moment decreases the electron–electron correlations below TSR and acts to further diminish the magnetoresistance.
Original languageEnglish
Pages (from-to)14726-14733
Number of pages8
JournalDalton Transactions
Volume47
Issue number41
Early online date28 Sep 2018
DOIs
Publication statusPublished - 7 Nov 2018

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