Macroscopic Properties in Incommensurate Magnetic Ordered Phases of PrB6 in Magnetic Field around the Direction

We measured the thermal expansion and magnetostriction of PrB 6 under the longitudinal magnetic fields up to 15 T for three magnetic field directions. We found the following results in the IC1 and IC2 phases for H ∥ . The magnetostriction shows only a small magnetic field dependence in the IC1 phase but exhibits a large shrinkage with increasing magnetic field roughly proportional to - H 2 in the IC2 phase. The thermal expansion exhibits a small change in the IC1 phase but a large increase in the IC2 phase with decreasing temperature. These different behaviors between the IC1 and IC2 phases originate from the existence of both χ || and χ ⊥ components exist in the IC1 phase and only the χ ⊥ component in the IC2 phase. The characteristic magnetic and magnetoelastic properties of the experimental results are reproduced by the simple calculation for the two sublattice model, although this model does not represent the incommensurate magnetic strucutres of PrB 6 . The important point is the weight of χ || a...