METAL-INSULATOR-TRANSITION IN LAYERED MANGANITES - (LA1-ZNDZ)(1.2)SR1.8MN2O7

Lattice effects on the anisotropic magnetic and transport properties h ave been investigated for single crystals of (La1-zNdz)(1.2)Sr1.8Mn2O7 with a layered structure. The ferromagnetic transition temperature T- C is suppressed from T-C=130 K for z=0.0 to 80 K for z=0.2, and eventu ally the transition disappears beyond z=0.4. From the significant chan ge of the magnetic anisotropy, we have found that the suppression orig inates from the increasing d(3z2-r2) character in the occupied e(g) st ate due to the Jahn-Teller distortion of the MnO6 octahedra. Our obser vations indicate that the effects of chemical substitution are qualita tively different between the cubic and layered doped manganites.