Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo

Research Groups

Zenji Hiroi Group

Group of Solid State Physics (The Institute for Solid State Physics) [New Materials Science]

Zenji Hiroi Group

Inquiry

Home Page , TEL : +81-(0)4-7136-3445 FAX : +81-(0)4-7136-3446 , e-mail: hiroi@issp.u-tokyo.ac.jp


New horizon in materials science explored on
the basis of solid state chemistry and physics

We are exploring exotic phenomena such as superconductivity and quantum magnetism in solid state physics by searching for new materials using various techniques in solid state chemistry. Myriad of electrons in a crystal can move around almost freely to give a metallic conduction and sometimes exhibit superconductivity below a critical temperature Tc by forming quantum-mechanical pairs called Cooper pairs. New compounds with higher Tcs, hopefully above room temperature, are desired for future applications and would be achieved by finding a new strong "glue" for Cooper pairs. On the other hand, once electrons stop at each atom to be localized, the spin degree of freedom emerges. Particularly, when they are located on lattice points of the triangle geometry, magnetic frustration takes place, which tends to suppress conventional magnetic order and may lead to an exotic spin "liquid" state at absolute zero temperature. We are now looking for model compounds to study these interesting phenomena and trying to uncover the physics behind.

Professor Zenji Hiroi

Profile

Professor Zenji Hiroi

  • 1983 Graduated from the Department of Chemistry, Faculty of Science, Kyoto University
  • 1987 Graduated from the Graduate School of Science, Kyoto University
  • 1989 Doctor of Science, Kyoto University
  • 1989 Technical Associate, Institute for Chemical Research (ICR), Kyoto University
  • 1992 Research Associate, ICR, Kyoto University
  • 1995 Associate Professor, ICR, Kyoto University
  • 1998 Associate Professor, Institute for Solid State Physics (ISSP), University of Tokyo
  • 2004 Professor, ISSP, University of Tokyo

Introduction of the study

Introduction of the study

The remarkable discovery of high-Tc superconductivity and the following enthusiastic research in the last decades have clearly demonstrated how the finding of new materials would give a great impact on the progress of materials research and solid state physics. Now related topics are spreading over not only superconductivity but also unusual metallic behavior that is generally observed near the metal-insulator transition in the strongly correlated electron systems. We believe that for the next few decades it will become more important to explore novel physics through searching for new materials. Transition-metal oxides are one of the most typical systems where the effect of Coulomb interactions plays a critical role on their magnetic and electronic properties. Especially interesting is what is expected when electrons localized due to the strong Coulomb repulsion start moving by changing the bandwidth or the number of carriers. We anticipate there an unknown, dramatic phenomenon governed by quantum fluctuations. Topics we are now studying are superconductivity hopefully with higher Tc values and quantum spin systems with the triangle geometry where a magnetic frustration may lead to an unusual spin liquid ground state. One of our recent progresses is that we found superconductivity for the first time in the pyrochlore oxides α-Cd2Re2O7 and β-AOs2O6 (A = K, Rb, Cs), as shown in the above figure.

Introduction of the study

Message from a senior

Hajime Ishikawa

Hajime Ishikawa

We talk with Professor Hiroi friendly on various topics on daily life as well as research. He always gives us important suggestions during discussion on research, from which we have learned a lot on the chemistry and physics of materials. Students can do their research in a relaxed atmosphere at their own paces in the Hiroi laboratory. I myself would like to open up a new horizon in materials science through the discovery of new compounds, the growth of high-quality single crystals and detailed physical characterizations.

Hajime Ishikawa