Dilatometric Measurements and Multipole Ordering in DyB_2C_2 and HoB_2C_2(Condensed Matter : Structure, Mechanical and Thermal Properties)

概要

論文の詳細を見る
We have performed dilatometric measurements by the capacitance method on tetragonal rare earth compounds DyB_2C_2 and HoB_2C_2 that show antiferro-quadrupole (AFQ) ordering. The tetragonal structure is invariant across the paramagnetic phase to the AFQ phase at T_Q=24.7K in DyB_2C_2. In the case of intermediate phase IV of HoB_2C_2, between T_<C1>=5.9K and T_<C2>=5.0K, the lattice length along the [101] direction reveals an abrupt increase, while the lengths along the [100] and [110] directions shrink slightly. This lattice distortion is described in terms of triclinic strain ε_<yz>=ε_<zx>≐̸0 indicating the spontaneous ferro-quadrupole moment <O_<yz>>=<O_<zx>>≐̸0. A plausible model, based on an octupole ordering <T_x>=<T_y>=<T_z>≐̸0, in phase IV of HoB_2C_2, is argued.
社団法人日本物理学会の論文
2005-06-15