Eur. Phys. J. B 1, 145-150 (1998)
https://doi.org/10.1007/s100510050164

Mn-site doping induced CMR properties in calcium rich manganites Pr_1-xCa_xMnO₃ (0.6 ≤ x ≤ 0.7)

Laboratoire CRISMAT, ISMRA ( CNRS UMR 6508) , 6 boulevard du Maréchal Juin, 14050 Caen Cedex, France

Corresponding author: ^a barnabe@crismat.ismra.fr

Received: 18 June 1997
Revised: 4 August 1997
Accepted: 10 November 1997
Published online: 15 January 1998

Abstract

Doping of Mn-site by chromium, cobalt and nickel has been investigated in the calcium rich manganites Pr_0.4Ca_0.6MnO₃ and Pr_0.3Ca_0.7MnO₃. Whatever the nature of the doping element, a rapid disappearance of the charge ordered (CO) state is observed, T_CO decreasing as the doping rate increases. But the most important result concerns the Cr-doped compounds Pr_0.4Ca_0.6Mn_1-xCr_xO₃ 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 Mn(IV) contents (Mn(IV)/Mn(III) ≥ 3/2) for x = 0.07-0.12 is shown for the first time, the resistance ratios R₀/R_7T reaching 2×10⁶ 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.