Heavy-fermion physics

Quantum critical point
When a phase transition temperature Tord is extremely small, the quantum mechanical effect plays an important role in physical properties. This quantum effect is one of our interests. We can control the T_ord by a parameter δ. We call a critical parameter δ_c Quantum Critical Point (QCP) reducing Tord to 0 K. Since the parameter δ experimentally corresponds to pressure, magnetic field, and substitution of atom, we investigate physical properties at low temperatures, high magnetic fields, and high pressures in order to observe the novel physics.

Pressure-induced superconductor
The competition of the Kondo effect and the RKKY(Ruderman-Kittle-Kasuya-Yosida) interaction leads to a small magnetic transition temperture in rare earth compounds. This is the reason why rare earth compounds can be good candidates to investigate the physical properties around QCP. The Kondo effect and the RKKY interaction are controled by pressure, which reduces the magnetic temperature and achieve the QCP in Ce compounds. Around the QCP, unconventiona superconductors mediated by a magnetic fluctuation have been reported. Addition to pressure, the magnetic field also affect the electronic state of sample. In this sense, we can create novel physics by applying external field.