Layered-Type Antiferromagnetic State in Double-Layered Manganites: (La_1-zNd_z)_2-2xSr_1+2xMn₂O₇

Abstract

Anisotropic magnetic and transport properties have been investigated for single crystals of layered-perovskite manganites (La 1- z Nd z ) 2-2 x Sr 1+2 x Mn 2 O 7 as a function of thendoping level x and averaged ionic radius z of the rare-earth ion. The ferromagnetic metallic (FM) state observed in La 1.2 Sr 1.8 Mn 2 O 7 ( x =0.4; z =0.0) disappears with increasing x or z , and the ground state is replaced by a layered antiferromagnetic (layered-AF) state beyond x ∼0.5. Thus obtained phase diagram is discussed in terms of variation of the e g -band structure with the band-filling (=1- x ).