Motoyama Gaku, Nishioka Takashi, Sato Noriaki K
Department of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
Phys Rev Lett. 2003 Apr 25;90(16):166402. doi: 10.1103/PhysRevLett.90.166402. Epub 2003 Apr 22.
We have carried out thermal expansion measurements on the heavy fermion compound URu2Si2. We have discovered a new anomaly that appears only under pressure for both the tetragonal a and c axes. Plotting these temperatures on a temperature-pressure plane, we have constructed a phase diagram, in which there is a first order phase transition boundary separating a hidden and antiferromagnetic order. When the system enters the antiferromagnetic phase from the hidden order, the lattice constant shrinks along the a axis and elongates along the c axis, leading to an increase in the lattice constant ratio of c/a. We conclude that the system lies close to a bicritical point from which the first order phase transition line emanates.
我们对重费米子化合物URu2Si2进行了热膨胀测量。我们发现了一种新的异常现象，该现象仅在压力作用下出现在四方晶系的a轴和c轴上。将这些温度绘制在温度-压力平面上，我们构建了一个相图，其中存在一个一阶相变边界，将隐藏序和反铁磁序分隔开来。当系统从隐藏序进入反铁磁相时，晶格常数沿a轴收缩，沿c轴伸长，导致c/a晶格常数比增加。我们得出结论，该系统接近一个双临界点，一阶相变线从该点发出。
