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The European Physical Journal B
ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)
Abstract Volume 1 Issue 2 (1998) pp 145-150
Mn-site doping induced CMR properties in calcium rich manganites $\mathsf{Pr_{{1-x}}Ca_{{x}}MnO_{ 3}}$ ($\mathsf{ 0.6\leq { x} \leq 0.7}$)
A. Barnabé (a), A. Maignan, M. Hervieu, B. Raveau
Laboratoire CRISMAT, ISMRA (CNRS UMR 6508), 6 boulevard du Maréchal Juin, 14050 Caen Cedex, France
Received: 18 June 1997 / Revised: 4 August 1997 / Accepted: 10 November 1997
Abstract: Doping of Mn-site by chromium, cobalt and nickel has been investigated in the calcium rich manganites ${\rm Pr}_{0.4}{\rm Ca}_{0.6}{\rm Mn}{\rm O}_3$ and ${\rm Pr}_{0.3}$${\rm Ca}_{0.7}$${\rm Mn}{\rm O}_3$. Whatever the nature of the doping element, a rapid disappearance of the charge ordered (CO) state is observed, $T_{\rm CO}$ decreasing as the doping rate increases. But the most important result concerns the Cr-doped compounds ${\rm Pr}_{0.4}{\rm Ca}_{0.6}{\rm Mn}_{1-x}{\rm Cr}_x{\rm O}_3$ for which a re-entrant insulator to metal transition at 90-120 K is observed for x=0.10-0.12, in a zero magnetic field. The possibility to induce colossal magnetoresistance (CMR) properties for high ${\rm Mn}$(IV) contents (${\rm Mn}$(IV)/${\rm Mn}{\rm (III)}\geq 3/2$) for x=0.07-0.12 is shown for the first time, the resistance ratios $R_0/R_{\rm 7T}$ reaching $2\times10^6$ at 30 K. This study also shows differently that the small size of the A-site cation (Pr, Ca) is not a redhibitory obstacle to the appearance of CMR properties in manganites, in contrast with previously established phase diagrams.
PACS. 71.30.+hMetal-insulator transitions and other electronic transitions - 75.30.CrSaturation moments and magnetic susceptibilities - 75.70.PaGiant magnetoresistance
(a) e-mail: barnabe@crismat.ismra.fr
Online publication: February 17, 1998
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