Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 35: Correlated Electrons - Quantum Critical Phenomena
TT 35.1: Vortrag
Mittwoch, 9. März 2005, 11:15–11:30, TU H104
Evidence for a ferromagnetic quantum critical point in CePd1−xRhx — •Christoph Geibel1, Julian Sereni2, Robert Küchler1, and Teodora Radu1 — 1MPI für Chemische Physik fester Stoffe, D-01187 Dresden, Germany — 2Centro Atomica Bariloche-CNEA, 8400 S.C. de Bariloche, Argentina
The behavior at the disappearance of magnetic order in Ce-based systems is presently a subject of strong interest. While their exist many Ce-based compounds showing an antiferromagnetic critical point, appropriate candidates for the study of the disappearance of a ferromagnetic (F) state are very scarce. Theories presently favor a first order critical point in pure systems, while disorder is suspected to lead to a continuous second order quantum critical point. One attractive candidate is the alloy CePd1−xRhx reported to evolve from an F - Ce3+ state at x = 0 to a non-magnetic, valence fluctuating state at x = 1. However, the disappearance of its F state has never been thoroughly investigated. We report here a detailled investigation of this system by means of ac-susceptibility (χ ′ac), specific heat (Cp) and thermal expansion (β) measurements. Our results indicate a continuous disappearance of the F-state, with Tc → 0 K at around xcr ≈ 0.85 as traced following the sharp χ ′ac(T) maximum. In the vicinity of the quantum critical point at xcr, power law behavior is observed in Cp (T) and in β (T). These results shall be discussed in the context of present theories