Fermi-surface collapse and dynamical scaling near a quantum-critical point

Sven Friedemann*, Niels Oeschler, Steffen Wirth, Cornelius Krellner, Christoph Geibel, Frank Steglich, Silke Paschen, Stefan Kirchner, Qimiao Si

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

103 Citations (Scopus)

Abstract

Quantum criticality arises when a macroscopic phase of matter undergoes a continuous transformation at zero temperature. While the collective fluctuations at quantum-critical points are being increasingly recognized as playing an important role in a wide range of quantummaterials, the nature of the underlying quantum-critical excitations remains poorly understood. Here we report in-depth measurements of the Hall effect in the heavy-fermion metal YbRh2Si2, a prototypical system for quantum criticality. We isolate a rapid crossover of the isothermal Hall coefficient clearly connected to the quantum-critical point from a smooth background contribution; the latter exists away from the quantum-critical point and is detectable through our studies only over a wide range of magnetic field. Importantly, the width of the critical crossover is proportional to temperature, which violates the predictions of conventional theory and is instead consistent with an energy over temperature, E/T, scaling of the quantum-critical single-electron fluctuation spectrum. Our results provide evidence that the quantum-dynamical scaling and a critical Kondo breakdown simultaneously operate in the same material. Correspondingly, we infer that macroscopic scale-invariant fluctuations emerge from the microscopic many-body excitations associated with a collapsing Fermi-surface. This insight is expected to be relevant to the unconventional finite-temperature behavior in a broad range of strongly correlated quantum systems.

Original languageEnglish
Pages (from-to)14547-14551
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number33
DOIs
Publication statusPublished - 17 Aug 2010

Keywords

  • YbRh2Si2
  • Kondo effect
  • magnetotransport
  • antiferromagnetism
  • local quantum criticality
  • T-C SUPERCONDUCTOR
  • PHASE-TRANSITIONS
  • METALS
  • LIQUID
  • HEAVY
  • YBRH2SI2
  • OSCILLATIONS
  • TEMPERATURE

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