  High-temperature superconductors (HTSC) and heavy-fermion (HF) metals exhibit
extraordinary properties. They are so unusual that the traditional Landau
paradigm of quasiparticles does not apply. It is widely believed that utterly
new concepts are required to describe the underlying physics. There is a
fundamental question: how many concepts do we need to describe the above
physical mechanisms? This cannot be answered on purely experimental or
theoretical grounds. Rather, we have to use both of them. Recently, in HTSC,
the new and exciting measurements have been performed, demonstrating a puzzling
magnetic field induced transition from non-Fermi liquid to Landau Fermi liquid
behavior. We show, that in spite of very different microscopic nature of HTSC
and HF metals, the behavior of HTSC is similar to that observed in HF
compounds. We employ a theory, based on fermion condensation quantum phase
transition which is able to resolve the above puzzles.
