Powder neutron diffraction study of HoCoGa

Kobayashi, Riki; Kaneko, Koji   ; Wakimoto, Shuichi  ; Chi, S.*; Sanada, Naoyuki*; Watanuki, Ryuta*; Suzuki, Kazuya*

We have studied the magnetic structure of HoCoGa which shows successive magnetic phase transition at = 9.6 K and = 7.5 K by using powder neutron diffraction. The data indicates magnetic reflection peaks with propagation vector = (1/2 0 0.35) at (AFIC phase), and then the propagation vector changes to = (1/2 0 1/2) below (AFC phase). In addition, the temperature dependence of magnetic reflection intensity shows temperature hysteresis at . These results suggest that the transition at is an incommensurate to commensurate first order transition. From our analysis, we have decided that the magnetic structure at 3.5 K is collinear antiferromagnetic one with propagation vector , and magnitude of magnetic moment is 8.6(2) along the -axis. This structure is same as TbCoGa which is proposed existence of component separated magnetic order due to the competition between magnetic and quadrupolar interactions.