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
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.
PACS: 71.27.+a – Strongly correlated electron systems; heavy fermions / 72.15.Gd – Galvanomagnetic and other magnetotransport effects / 75.10.-b – General theory and models of magnetic ordering
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998