Common field-induced quantum critical point in high-temperature superconductors and heavy-fermion metals
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.