Magnetic Properties and Magnetoresistance of HfFe₆Ge₆-Type Er_1-xGd_xMn₆Ge₆ and Ho_1-xGd_xMn₆Ge₆ (0.2 ≤ x ≤ 0.9) Compounds

Magnetic properties and magnetoresistance effects of the Er_1-xGd_xMn₆Ge₆ and Ho_1-xGd_xMn₆Ge₆ (0.2 ≤ x ≤ 0.9) compounds have been studied by magnetic property and resistivity measurements in applied magnetic field up to 5 T. For increasing Gd content, two series display a transition from the antiferromagnetic state to the ferrimagnetic state. The Er_1-xGd_xMn₆Ge₆(x = 0.2 and 0.5) and Ho_1-xGd_xMn₆Ge₆ (x = 0.2 and 0.4) compounds order antiferromagnetically at 430, 432, 423 and 425 K, respectively. The Er_1-xGd_xMn₆Ge₆ (x = 0.8 and 0.9) and Ho_1-xGd_xMn₆Ge₆ (x = 0.7, 0.8 and 0.9) compounds order ferrimagnetically at 462, 471, 450, 463 and 470 K, respectively. The Er_1-xGd_xMn₆Ge₆ and Ho_1-xGd_xMn₆Ge₆ compounds undergo the second transitions below 71 and 82 K, respectively. The magnetoresistance curves of the Er_0.1Gd_0.9Mn₆Ge₆ and Ho_0.1Gd_0.9Mn₆Ge₆ compounds in a field of 5 T are presented and the magnetoresistance effects are related to the metamagnetic transitions.