Studies of dissipative state in non-Kramers system Pr-based compounds

对PrMg_3的超声测量表明，弹性常数(C_(11-C_(12))/2)随磁场的变化具有很强的磁各向异性。通过低温热膨胀实验测得PrMg3的低温小Gruneisen常数为5。这一结果表明PrMg3具有小态密度的锯齿状准粒子。我们还对PrV2Al20进行了比热和磁化强度的测量。我们的测量表明，PrV2Al20在零场下Tq=0.73K和T*=0.61K时出现两相转变。我们描述了三个主要方向的T-H相图。需要强调的是，高场相只存在于[100]场方向。我们提出高场相是由于在八极矩的辅助下从电四极O20相转变到O22相的结果。

Ultrasonic measurements on PrMg3 reveals that the magnetic field dependence of elastic constant (C11-C12)/2 shows strong magnetic anisotropy. We obtained small Gruneisen constant of 5 for PrMg3 at low temperatures from low-temperature thermal expansion measurements. This result implies that PrMg3 has sermonic quasiparticles with small density of states. We have also performed specific heat and magnetization measurements on PrV2Al20. Our measurements reveals that PrV2Al20 exhibits two-phase transition at TQ = 0.73 K and T* = 0.61 K at zero field. We describe a T-H phase diagram in the three principal directions. It should be emphasized that high field phase exists in only [100] field direction. We proposed that the high field phase is due to the switching from the electric quadrupole O20 phase to O22 phase assisted by the octupole moment.