High-magnetic-fields thermodynamics of the heavy-fermion metal YbRh₂Si₂

¹ Petersburg Nuclear Physics Institute - Gatchina, 188300, Russia
² Komi Science Center, Ural Division, RAS - Syktyvkar, 167982, Russia
³ Opole University, Institute of Physics - Opole, 45-052, Poland, EU
⁴ St. Petersburg Division of the Classical Academy - Varshavskaya street 50/2, St. Petersburg, Russia
⁵ Opole University, Institute of Mathematics and Informatics - Opole, 45-052, Poland, EU

^a vrshag@thd.pnpi.spb.ru
^b stef@math.uni.opole.pl

Received: 1 November 2010
Accepted: 22 December 2010

Abstract

We perform a comprehensive theoretical analysis of the high-magnetic-field behavior of the heavy-fermion (HF) compound YbRh₂Si₂. At low magnetic fields B, YbRh₂Si₂ has a quantum critical point related to the suppression of antiferromagnetic ordering at a critical magnetic field B⊥c of B = B_c0 ≃ 0.06 T. Our calculations of the thermodynamic properties of YbRh₂Si₂ in wide magnetic field range from B_c0 ≃ 0.06 T to B ≃ 18 T allow us to straddle a possible metamagnetic transition region and probe the properties of both low-field HF liquid and high-field fully polarized one. Namely, high magnetic fields B∼B^*∼10 T fully polarize the corresponding quasiparticle band generating a Landau-Fermi-liquid (LFL) state and suppressing the HF (actually NFL) one, while at increasing temperatures both the HF state and the corresponding NFL properties are restored. Our calculations are in good agreement with experimental facts and show that the fermion condensation quantum phase transition is indeed responsible for the observed NFL behavior and quasiparticles survive both high temperatures and high magnetic fields.