Scaling of the magnetic entropy and magnetization in   YbRh_2(Si_{0.95}Ge_{0.05})_2
  The magnetic entropy of YbRh_2(Si_{0.95}Ge_{0.05})_2 is derived from low-temperature ($T\geq 18$ mK) specific heat measurements. Upon field-tuning the system to its antiferromagnetic quantum critical point unique temperature over magnetic field scaling is observed indicating the disintegration of heavy quasiparticles. The field dependence of the entropy equals the temperature dependence of the dc-magnetization as expected from the Maxwell relation. This proves that the quantum-critical fluctuations affect the thermal and magnetic properties in a consistent way. 
P. Gegenwart, Y. Tokiwa, K. Neumaier, C. Geibel, F. Steglich