Investigation of Strongly Correlated Electron Systems using Multi-Extreme Conditions

该项目的目标是建立实验室技术，用于测量各种极端条件下材料的基本性质，包括低温、高压、强磁场及其组合，并应用实验技术从电子学角度控制和理解强相关f-和d-电子系统的各种异常性质。以下是我们三年来的研究成果总结。我们还发表了34篇与该项目有关的论文。1）已建立的技术是在高达12 T的高场中测量低温下至15 mK的电阻率和磁化率，比热和弹性模量低至60 mK高达14 T，在高达8 GPa的高压下电阻率低至1.5 K，2）对f电子化合物CeSb、CeRu_2、CeFe_2、CeTe_2、LuB_2<12>、CeNiSn、Ce（Ni，Cu）Sn、YbPtSn、UPt、UNiSn、UNiAl、UirGe、UirGe、UCu_2Sn、d电子氧化物La_<1-x>Sr_xCuO_4、La_ Nd_ySr_xCuO_4<2-x-y>、Sr_2RuO_4、Sr_<3-x>Ca_xRu_2O_7进行了测量。我们发现了一些具有特征序的反常基态，包括反铁磁性、铁磁性、二维d波超导、p波超导、铁四极序、反铁四极序、中间价态。

The objectives of this project are to establish laboratory techniques for measuring fundamental properties of materials under various extreme conditions, including low temperatures, high pressures, strong magnetic fields and their combinations, and to apply the experimental techniques to controlling and understanding a variety of anomalous properties of the strongly correlated f- and d-electron systems from electronic points of view. The following is a summary of our research results which we performed during 3 years. We also published 34 papers in relation to this project.1) Established techniques are for measurements of electric resistivity and magnetic susceptibility at low temperatures down to 15 mK in high fields up to 12 T, of specific heat and elastic modulus down to 60 mK up to 14 T, of resistivity down to 1.5 K under high pressures up to 8 GPa, and of resistivity and specific heat under triple-extreme conditions of temperature down to 100 mK, field up to 8 T and pressure up to 2 GPa.2) We performed various measurements on f-electron compounds : CeSb, CeRu_2, CeFe_2, CeTe_2, LuB_<12>, CeNiSn, Ce(Ni, Cu)Sn, YbPtSn UPt, UNiSn, UNiAl, UirGe, URhGe, UCu_2Sn,d-electron Oxide : La_<1-x>Sr_xCuO_4, La_<2-x-y>Nd_ySr_xCuO_4, Sr_2RuO_4, Sr_<3-x>Ca_xRu_2O_7.3) We revealed a number of anomalous ground states with characteristic orders including antiferromagnetism, ferromagnetism, 2-dimensional d-wave Superconductivity, p-wave superconductivity, ferro-quadrupole order, antiferro-quadrupole order, intermediate valence state.