Eur. Phys. J. B 3, 185-188 (1998)
https://doi.org/10.1007/s100510050301

Magnetic phase diagram of perovskite Mn oxides at T=0

¹ Department of Physics, Nanjing University, Nanjing 210008, P.R. China
² National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210008, P.R. China
³ Center for Advanced Studies in Science and Technology of Microstructures, Nanjing 210093, P.R. China

Corresponding author: ^a zyq@netra.nju.edu.cn

Received: 11 July 1996
Revised: 7 December 1996
Accepted: 24 July 1997
Published online: 15 May 1998

Abstract

Minimizing total free energy by numerical calculations, we obtain the magnetic phase diagram of perovskite Mn oxides, such as with X=Ba, Ca, Sr, etc. in the whole doping region from x=0 to x=1 at temperature T=0. It is discovered that a spiral state is stable in a low concentration of X ions while a canted state is stable in a high concentration of X ions, and a ferromagnetic phase can exist in the intermediate concentrations when the antiferromagnetic interaction is weak. The energy difference between spiral and canted states is found to be small when the Hund coupling is large. Magnetic field induced spiral/canted phase transition is considered as a possible mechanism of the colossal magnetoresistance (CMR) in the Mn oxides.