Phenomena of elementary excitation in rear-earth materials under pressure, magnetic field at low temperatures

本课题的目的是在低温高压高磁场条件下寻找包含电荷波动稀土元素的各种材料的异常现象。研制了一种用于原位x射线衍射和电阻测量的高压仪器，该仪器使用立方砧，工作温度从300 K到7K，压力为10gpa。采用流体静压仪和单轴压力仪，结合SQUID磁力计进行了压力下的磁化测量。工作在300K到1.5K，压力分别达到1GPa和0.5GPa。采用改进的Bridgman铁砧，建立了一种在高达8GPa压力下的低温下精确测量磁输运的技术。开发了一种高压下的XAFS技术，用于使用传统的x射线发生器与金刚石砧相结合来测量价跃迁。利用上述仪器，我们观察到稀土元素Ce、Pr、Eu、Sm、Tm、Yb、Lu等多种材料在输运和磁性方面的许多前所未有的现象：CeP、Ce_<0.9>La_<0.1>P、CeP_<0.9>N_<0.1>、Ce_2Fe_<17>、CePtGa、Ces_3SnC、Ce_3PbC、Ce_3Pd_<20>Si_6、Ce_<0.5>La_<0.5> b6、CeNi、CeSbNi_x、PrInAg_2、PrCu_2、EuNi_2(Ge_<1-X>Si_x)_2、SmS、TmTe、TmSe、YbAs、YbInCu_4、Yb_4(As_< 1-X> Sb_x)_3、Lu(Co_<1-X>Al_x)_2。

The purpose of this project is to search various materials that include charge fluctuating rare-earth elements for unusual phenomena under high pressure and high magnetic field at low temperatures.1. A high pressure apparatus for in-situ X-ray diffraction and electrical resistance measurements was developed using cubic anvils, which works at low temperatures from 300 K down to 7K under pressure of 10GPa.2. Hydrostatic and uniaxial pressure apparatuses combined with a SQUID magnetometer were made for magnetization measurements under pressure. Those work from 300K to 1.5K under pressure up to 1GPa and 0.5GPa, respectively.3. A technique for precise magneto-transport measurements at low temperatures under pressure up to 8GPa was established by applying a modified Bridgman anvil.4. A technique for XAFS under high pressure was developed for measurements of valence transition using a conventional X-ray generator combined with diamond anvils.5. By using above mentioned apparatus, we observed many unprecedented phenomena in the transport and magnetic properties of various materials, which include one of rare-earth elements, Ce, Pr, Eu, Sm, Tm, Yb and Lu, as follows : CeP, Ce_<0.9>La_<0.1>P, CeP_<0.9>N_<0.1>, Ce_2Fe_<17>, CePtGa, Ces_3SnC, Ce_3PbC, Ce_3Pd_<20>Si_6, Ce_<0.5>La_<0.5>B 6, CeNi, CeSbNi_x, PrInAg_2, PrCu_2, EuNi_2(Ge_<1-X>Si_x)_2, SmS, TmTe, TmSe, YbAs, YbInCu_4, Yb_4As_3, Yb_4(As_<1-x>Sb_x)_3, Lu(Co_<1-X>Al_x)_2.