Neutron Investigation of Tb_1-xCa_xMnO₃ (x ≥ 0.5)

Abstract

Crystal and magnetic structures of Tb_1-xCa_xMnO₃ (x ≥ 0.5) have been investigated by means of neutron powder diffraction experiments. We have derived the magnetic phase diagram against hole concentration x and temperature T: the spin structure changes as CE- → C- → G-type structure with increase of x. In the vicinity of the magnetic phase boundaries, magnetically phase separated state has been observed. At high temperature region, we observe the metallic behavior in a wide x region (0.70 ≤ x ≤ 0.95), and ascribe it to the enhanced one-electron bandwidth W of the e_g state.