The Impact of Quantum-critical Instabilities on the Magnetic Phase Diagram of CePdAl

Long-range magne􀆟c order of heavy-fermion compounds can be suppressed along two,
fundamentally different routes: either by screening the magne􀆟c moments by virtue of the Kondo
effect, or by affec􀆟ng the magne􀆟c interac􀆟ons between moments by geometric frustra􀆟on or
reduced dimensionality. It is expected that the interplay between these different quantum-cri􀆟cal
fluctua􀆟ons gives rise to the emergence of novel electronic states. The heavy-fermion compound
CePdAl adopts a distorted kagome crystal structure and is, therefore, in close proximity to both
instabili􀆟es. Recent transport and μSR measurements under hydrosta􀆟c pressure show that at the
border to long-range an􀆟ferromagne􀆟c order, an anomalous quantum-cri􀆟cal state with spinliquid-
like proper􀆟es emerges [1,2]. To explore the impact of the quantum-cri􀆟cal instabili􀆟es on
the phase diagram of CePdAl we used thermal-expansion, magnetostric􀆟on, and magne􀆟za􀆟on
measurements in a wide temperature and field range. The uniaxial-pressure, field, and
temperature dependence of the entropy was employed to infer the underlying characteris􀆟c
energies and to disentangle their effect on the different phases. ... mehrThe resul􀆟ng, extended phase
diagram is compared with those of other related compounds and will be discussed in context with
the global phase diagram of heavy-fermion systems.