# Dresden 2006 – wissenschaftliches Programm

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# TT: Tiefe Temperaturen

## TT 3: Correlated Electrons: Quantum-Critical Phenomena

### TT 3.1: Vortrag

### Montag, 27. März 2006, 09:30–09:45, HSZ 301

**Smeared Ferromagnetic Quantum Phase Transition in CePd**_{1−x}**Rh**_{x} — •Tanja Westerkamp, Robert Küchler, Adam Pikul, Nubia Caroca-Canales, Micha Deppe, Philipp Gegenwart, Julian Sereni, Christoph Geibel, and Frank Steglich — Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden

Quantum phase transitions in Ce-based systems are presently a
subject of strong interest. While there exists a number of
compounds showing an antiferromagnetic quantum critical point
(QCP), appropriate candidates for the study of the disappearance
of a ferromagnetic (FM) state are very scarce. Theories favor a
first-order transition in pure systems, while disorder might lead
to a continuous second order QCP. In this respect the alloy
CePd_{1−x}Rh_{x} might be interesting, because it evolves from
a FM Ce^{3+} state at *x*=0 to a non-magnetic, valence
fluctuating state at *x*=1.
A detailed investigation of this system by means of
ac-susceptibility and specific heat at *T*≥ 0.4 K as well as
thermal expansion at *T*≥ 0.1 K suggests a continuous
suppression of the FM order. However, *T*_{C}(*x*) shows an extended tale and the Grüneisen-ratio analysis raises doubts on a well defined QCP.
Here, we report ac-susceptibility measurements down to very low
temperatures *T*≥ 0.02 K at concentrations in the tale region
of the phase diagram which characterize the nature of the quantum
phase transition in this system.