Collapse and Enhancement of the Heavy Fermion State in CeCu6 under Magnetic Field and Pressure

We measured the electrical resistivity under magnetic field and pressure and de Haas van Alphen (dHvA) oscillations in CeCu6. The A value in the Fermi liquid relation of the electrical resistivity rho = rho 0 + AT(2) and the cyclotron effective mass are reduced with increasing magnetic fields and pressures. The A value, however, becomes distinct and/or is enhanced at the metamagnetic field, especially, in a characteristic pressure region where the electronic state deviates from the heavy fermion state, for example, at 2.00 GPa.