A study of the LaMn2-xCuxGe2 (0<=x<=1) solid solution by magnetization and neutron diffraction measurements

Crystallographic and magnetic properties of LaMn2-xCuxGe2 (0 less than or equal to x less than or equal to) compounds have been investigated. All compounds display spontaneous magnetization ar 4.2 K. The onset of ferromagnetism at T-c decreases with the copper content from 327 K for x = 0 to 120 K for x = 1. Neutron diffraction patterns for LaMn2-xCuxGex (x = 1, 0.5, 0.25) compounds have been recorded, indicating thr occurrence of purely antiferromagnetic Mn (001) planes for T-N > T > T-c. The Neel temperature T-N decreases from 310 K for x = 0.5 to 250 K for x = 1. A partial x-T magnetic phase diagram of the LaMn2-xCuxGe2 system is proposed, The stability of the different magnetic structures is discussed and the results are compared with those of the LaMn2-xFexGe2 and NdMn2-xFexCe2 systems. rile enhancement of the Ge-Ge bund when replacing Fe by Cu seems to play a role in the evolution of the magnetic properties.