Experimental studies of the antiferromagnetic (AF) heavy fermion metal YbRh2Si2 in a magnetic field B indicate the presence of a jump in the Hall coefficient at a magnetic-field tuned quantum state in the zero temperature limit. This quantum state occurs at B≥Bc0 and induces the jump even though the change of the magnetic field at B=Bc0 is infinitesimal. We investigate this by using the model of heavy electron liquid with the fermion condensate. Within this model the jump takes place when the magnetic field reaches the critical value Bc0 at which the ordering temperature TN(B=Bc0) of the AF transition vanishes. We show that at B→Bc0, this second order AF phase transition becomes the first order one, making the corresponding quantum and thermal critical fluctuations vanish at the jump. At T→0 and B=Bc0, the Gr\"uneisen ratio as a function of temperature T diverges. We demonstrate that both the divergence and the jump are determined by the specific low temperature behavior of the entropy S(T)∝S0+aT+bT with S0, a and b are temperature independent constants.
@article{arxiv.cond-mat/0506794,
title = {Hall coefficient in heavy fermion metals},
author = {V. R. Shaginyan and K. G. Popov and S. A. Artamonov},
journal= {arXiv preprint arXiv:cond-mat/0506794},
year = {2009}
}