HOMMA Yoshiya Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (00260448)
SHIOKAWA Yoshinobu Tohoku University, Institute for Materials Research, Professor, 金属材料研究所, 教授 (50111307)
|Budget Amount *help
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Ternary intermetallics with composition 2:1:3 are mainly investigated in this work. The obtained results are summarized as following. (1)5f electronic compounds U_2TSi_3 (T=transition metal): Fundamental physical property measurements reveal that compounds with T=Pd,Pt and Au are simple spin glass materials, and those with T=Rh,Ni,Co and Ir show typical spin glass behavior accompanied with short-range ferromagnetic ordering. Moreover, it is confirmed that compounds U_2TSi_3 (T=Co,Ni,Rh,Pd and Pt) and U_2IrSi_3 are XY-type and Ising spin glass compounds, respectively. (2)4f electronic compounds R_2TSi_3 (R=rare earth metal): it is found that Nd_2PdSi_3 is a ferromagnet with weak spin glass behavior,Th_2PdSi_3 and Dy_2PdSi_3 are typical reentrant spin-glass materials, and Nd_2AgIn_3,Pr_2AgIn_3,Nd_2CuIn_3 and Pr_2CuIn_3 are antiferromagnetic cluster glass compounds with freezing temperature T_f=12.6,4.0,14.1 and 5.4 K, respectively. Otherwise, we have prepared a lot of kinds of ternary intermetallics with other compositions such as 1:2:2,1:1:1,1:4:8,3:2:4,3:4:4,2:1:6,and confirmed that UAuSi,UAuAl,Ge-rich UCuGe and PrCoRuSi are long-range magnetic ordering systems with spin glass behaviors. f-d(f-p) hybridization and RKKY exchange interactions are considered to play a important role in the formation of NMAD spin glass state in 5f and 4f electronic systems, respectively. Moreover, the random distribution of nonmagnetic atoms could destroy the long-range magnetic ordering, and results in the formation of magnetic cluster. This is the reason why many NMAD materials show cluster glass behavior.