  Low-temperature specific-heat measurements on YbRh2Si2 at the second order
antiferromagnetic (AF) phase transition reveal a sharp peak at TN=72 mK. The
corresponding critical exponent alpha turns out to be alpha=0.38, which differs
significantly from that obtained within the framework of the fluctuation theory
of second order phase transitions based on the scale invariance, where
alpha=0.1. We show that under the application of magnetic field the curve of
the second order AF phase transitions passes into a curve of the first order
ones at the tricritical point leading to a violation of the critical
universality of the fluctuation theory. This change of the phase transition is
generated by the fermion condensation quantum phase transition. Near the
tricritical point the Landau theory of second order phase transitions is
applicable and gives alpha=1/2. We demonstrate that this value of alpha is in
good agreement with the specific-heat measurements.
