General Properties of Phase Diagrams of Heavy-Fermion Metals

We study the temperature-magnetic field T-B phase diagrams of heavy-fermion (HF) metals, and show that at sufficiently high temperatures outside the ordered phase the crossover temperature , regarded as the energy scale, follows a linear B-dependence, crossing the origin of the T-B phase diagram. This behavior of constitutes the general property, and is formed by the presence of the fermion condensation quantum phase transition hidden within the ordered phase. Our result is in good agreement with the experimental T-B phase diagram of the HF metals YbRh2Si2, Yb(Rh0.93Co0.07)2Si2, and Yb(Rh0.94Ir0.06)2Si2. To support our observations, we analyze the isothermal magnetization M, and demonstrate that exhibits a universal temperature behavior over magnetic field scaling. The obtained results are in good agreement with the corresponding data collected on YbRh2Si2 as a function of the magnetic field at different temperatures under hydrostatic pressure.