Hall-effect evolution across a heavy-fermion quantum critical point.
Silke Paschen,T. Lühmann,Steffen Wirth,Philipp Gegenwart,O. Trovarelli,C. Geibel,Frank Steglich,Piers Coleman,Qimiao Si +8 more
TLDR
Measurements of the low-temperature Hall coefficient (RH)—a measure of the Fermi surface volume—in the heavy-fermion metal YbRh2Si2 upon field-tuning it from an antiferromagnetic to a paramagnetic state are reported.Abstract:
A quantum critical point (QCP) develops in a material at absolute zero when a new form of order smoothly emerges in its ground state. QCPs are of great current interest because of their singular ability to influence the finite temperature properties of materials. Recently, heavy-fermion metals have played a key role in the study of antiferromagnetic QCPs. To accommodate the heavy electrons, the Fermi surface of the heavy-fermion paramagnet is larger than that of an antiferromagnet1,2,3. An important unsolved question is whether the Fermi surface transformation at the QCP develops gradually, as expected if the magnetism is of spin-density-wave (SDW) type4,5, or suddenly, as expected if the heavy electrons are abruptly localized by magnetism6,7,8. Here we report measurements of the low-temperature Hall coefficient (RH)—a measure of the Fermi surface volume—in the heavy-fermion metal YbRh2Si2 upon field-tuning it from an antiferromagnetic to a paramagnetic state. RH undergoes an increasingly rapid change near the QCP as the temperature is lowered, extrapolating to a sudden jump in the zero temperature limit. We interpret these results in terms of a collapse of the large Fermi surface and of the heavy-fermion state itself precisely at the QCP.read more
Citations
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Fermi-liquid instabilities at magnetic quantum phase transitions
TL;DR: In this article, the authors discuss the instabilities of the Fermi-liquid state of conduction electrons in metals with particular emphasis on magnetic quantum critical points, with the aim of assessing the validity of presently available theory.
Journal ArticleDOI
Quantum criticality in heavy-fermion metals
TL;DR: In this paper, the authors summarize some of the basic issues, including the extent to which the quantum criticality in heavy-fermion metals goes beyond the standard theory of order-parameter fluctuations, the nature of the Kondo effect in the quantum-critical regime, the non-Fermi-liquid phenomena that accompany quantum criticalities and the interplay between quantum criticalness and unconventional superconductivity.
Journal ArticleDOI
Heavy Fermions and Quantum Phase Transitions
Qimiao Si,Frank Steglich +1 more
TL;DR: Recent years have seen the identification of continuous quantum phase transitions, or quantum critical points, in a host of antiferromagnetic heavy-fermion compounds and quantum criticality has provided fresh insights into the electronic, magnetic, and superconducting properties of the heavy-FERmion metals.
Journal ArticleDOI
Multiple Energy Scales at a Quantum Critical Point
Philipp Gegenwart,T. Westerkamp,Cornelius Krellner,Yoshifumi Tokiwa,Silke Paschen,C. Geibel,Frank Steglich,Elihu Abrahams,Qimiao Si +8 more
TL;DR: In this article, thermodynamic measurements in a magnetic-field-driven quantum critical point of a heavy fermion metal, YbRh2Si2, were reported, which provided evidence for an energy scale in the equilibrium excitation spectrum that is in addition to the one expected from the slow fluctuations of the order parameter.
Journal ArticleDOI
Quantum Criticality Without Tuning in the Mixed Valence Compound β-YbAlB4
Yosuke Matsumoto,Satoru Nakatsuji,Kentaro Kuga,Yoshitomo Karaki,Naoki Horie,Yasuyuki Shimura,Toshiro Sakakibara,Andriy H. Nevidomskyy,Andriy H. Nevidomskyy,Piers Coleman,Piers Coleman +10 more
TL;DR: High-precision magnetization measurements of the ultrapure f-electron–based superconductor β-YbAlB4 demonstrate a scaling of its free energy that is indicative of zero-field quantum criticality without tuning in a metal.
References
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