ALMOST LOCALIZED FERMIONS IN A MAGNETIC-FIELD - PROPERTIES AT THE METAMAGNETIC TRANSITION

We present applied magnetic-field dependences of the magnetization, li near specific heat, and de Haas-van Alphen oscillations for the almost -localized Fermi liquid (ALFL) close to the metamagnetic transition. T he analysis is performed within the mean-field slave-boson approach, w hich provides a realistic description in the strong applied-field limi t. The Fermi liquid is thermodynamically unstable at the metamagnetic point, at which it is proposed that the system transforms into a stati stical spin liquid (SSL) in the partially-filled-band case. This trans ition corresponds to the Mott-Hubbard localization in the half-filled band situation. The effective mass in the ALFL phase is spin dependent and large, whereas it is spin independent and has a band value in the SSL phase.