Eur. Phys. J. B 16, 469-474 (2000)
https://doi.org/10.1007/s100510070205

Extension of ferromagnetism and metallicity to electron-rich manganites by Ru-doping: Generation of new CMR oxides Sm_0.2Ca_0.8Mn_1-xRu_xO₃

¹ Laboratoire CRISMAT (UMR 6508 associée au CNRS) , ISMRA, 6 boulevard du Maréchal Juin, 14050 Caen Cedex, France
² Institute of Physics of ASCR, Cukrovarnicka 10, 16253 Praha 6, Czech Republic

Corresponding author: ^a christine.martin@ismra.fr

Received: 2 March 2000
Published online: 15 August 2000

Abstract

The doping of Mn site with ruthenium, in the n-type manganite Sm_0.2Ca_0.8MnO₃, has been studied using magnetic and transport measurements. We show that Ru induces a ferromagnetic metallic state at low temperature in this Mn⁴⁺ rich compound, a metal to metal transition replacing the metal to insulator one in the pristine phase. A spectacular increase of T_C up to 240 K is achieved, together with CMR effect. Based on thermoelectric power measurements, we propose that Ru(V) could be at the origin of these exceptional properties, due to ferromagnetic superexchange interactions between Ru(V) and Mn(III), forming in a first step ferromagnetic metallic clusters in the C-type antiferromagnetic insulating matrix.