Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 16: CE: Quantum-Critical Phenomena 1
TT 16.1: Vortrag
Dienstag, 23. März 2010, 14:00–14:15, H19
Specific heat and magnetocaloric effect at the field-induced quantum-critical point in CeCu5.7Au0.3 — •Michael J. Wolf, Gernot Goll, Veronika Fritsch, and Hilbert v. Löhneysen — Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany
The heavy-fermion system CeCu6−xAux can be tuned to a quantum critical point by application of different tuning parameters such as pressure or magnetic field. We present specific heat measurements on single crystalline CeCu5.7Au0.3 in the temperature range from 70 mK to 1.5 K and in magnetic fields up to 4 T with B ∥ c. In addition, the magnetocaloric effect was measured in the temperature range from 70 mK to 1 K and in magnetic fields up to 2 T. The critical magnetic field Bc was determined to be Bc = 0.95±0.1 T. At the critical magnetic field the specific heat data can be well described by the self-consistent spin-fluctuation model of Moriya and Takimoto [1]. The magnetocaloric data at low temperatures show a jump of the magnetic Grüneisen ratio at the phase boundary for B < Bc as well as a monotonic increase towards the lowest measured temperatures for B > Bc. These results are compared to previous magnetization measurements and discussed within the framework of theoretical models.
[1] T. Moriya and T. Takimoto, J. Phys. Soc. Japan 64 (1995), 960.