Peculiarities in low temperature properties of doped manganites A(1-x)B(x)MnO(3)

The phase diagram and low temperature properties of the doped manganites A( 1-x)B(x)MnO(3) are discussed for the concentrations x less than or equal to 0.4. The transition from insulating antiferromagnetic to metallic ferromag netic state at x(cr) similar or equal to 0.16 is treated by means of percol ation theory. The unifying description of insulating and metallic states is presented. The undoped manganite is a band insulator consisting of ferroma gnetic layers, which are coupled antiferromagnetically along the c directio n with a low Neel temperature. The metallic phase can be described by the t wo-band Fermi liquid picture. The behavior of conductivity, spin wave excit ations, etc. is analyzed and the comparison with experimental data is carri ed out.