New Phase of Matter in Multidisciplinary Approach

我们的主要目标是通过阐明强相关物质中超导性和磁有序性的物质新相，以及通过多学科方法测量材料的特性来创造独特的材料，从而在材料科学中建立新的概念。我们列出了该项目所取得的显著成果。反铁磁性（AFM）和超导性（SC）在单一CuO_2层中均匀共存相的发现，使我们揭示了它们真正的相图，包括AF量子临界点，这与以前认为的高T_c铜氧化物超导体的相图作为载流子掺杂水平的函数有很大不同.在前人研究的基础上，揭示了重费米子（HF）化合物CeRhIn_5的温度（T）-压力（P）相图中存在一个四临界点.在UGe_2中发现了铁磁性和超导相共存的量子一级相变.发现了新的压力感应超导体CeNiGe_3和Ce_2Ni_3Ge_5.不具有反转对称性的HF化合物如UIr和CeIrSi_3的压力诱导超导的发现，指出了一种新的、独特的超导态的可能性。Miyake等人等的理论解释了HF化合物高温超导的出现。这些关于强关联物质新相的发现，将有助于我们对HF化合物和高温超导体中非常规超导机制的理解，而这是它们发现以来的一个长期问题。

Our main objectives have established new concepts in materials science through the elucidation of the new phases of matter that underlies the superconductivity and magnetic ordering in strongly correlated matter, and the creation of unique materials, by measuring the properties of the materials in multidisciplinary approach. We list up the remarkable results obtained by this project.1. The discovery of the uniformly coexisting phase of antiferromagnetism (AFM) and superconductivity (SC) in a single CuO_2 layer has lead us to uncover their genuine phase diagram including an AF quantum critical point, which significantly differs from the previously believed phase diagrams as the function of carrier doping level for high-T_c copper-oxides superconductors.2. A tetracritical point in the temperature(T)-pressure(P) phase diagram of the heavy-fermion (HF) compound CeRhIn_5 was unraveled against the previous research results.3. The coexistence phase of ferromagnetism and SC was identified in UGe_2 around a quantum first-order phase transition.4. Novel pressure-induced superconductors CeNiGe_3 and Ce_2Ni_3Ge_5 were discovered.5. The discovery of the pressure-induced SC of HF compounds without inversion symmetry, such as UIr and CeIrSi_3 has pointed to the possibility of a new and unique superconducting state.6. Miyake, et. al. have been able to explain the appearance of high-T_c SC for HF compounds with the sudden change in the. valence number of Ce upon the application of pressure, by a novel anisotropic SC mechanism triggered by the critical valence number fluctuation.These remarkable findings on the new phases of strongly correlated matter would lead us to a coherent understanding of the mechanism of unconventional SC in HF compounds and high-T_c superconductors which is a long-term issue since their discoveries.