Magnetic-Field Induced Quantum Critical Point in YbRh₂Si₂

الأصل · EN

We report low-temperature calorimetric, magnetic and resistivity measurements on the antiferromagnetic (AF) heavy-fermion metal YbRh₂Si₂ (Tₙ = 70 mK) as a function of magnetic field B. While for fields exceeding the critical value Bc₀ at which Tₙ→0 the low temperature resistivity shows an AT² dependence, a 1/(B-Bc₀) divergence of A(B) upon reducing B to Bc₀ suggests singular scattering at the whole Fermi surface and a divergence of the heavy quasiparticle mass. The observations are interpreted in terms of a new type of quantum critical point separating a weakly AF ordered from a weakly polarized heavy Landau-Fermi liquid state.