Ferromagnetic quantum criticality studied by hall effect measurements in UCoAl

Tristan Combier, Dai Aoki, Georg Knebel, Jacques Flouquet

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12 Citations (Scopus)


Hall effect measurements were performed under pressure and magnetic field up to 2.2 GPa and 16 T on a single crystal of UCoAl. At ambient pressure, the system undergoes a first order metamagnetic transition at the critical field Bm = 0:7 T from a paramagnetic ground state to a field-induced ferromagnetic state. The Hall signal is linear at low field and shows a step-like anomaly at the transition, with only little change of the Hall coefficient. The anomaly is sharpest at the temperature of the critical end point T0 = 12K above which the first order metamagnetic transition becomes a crossover. Under pressure Bm increases and T0 decreases. The step-like anomaly in the Hall effect disappears at PM ≈ 1:3 GPa and the metamagnetic transition is not detected above the quantum critical end point (QCEP) at PΔ ≈ 1:7 GPa, Bm ≈ 7 T. Using magnetization data, we analyse our Hall resistivity data at ambient pressure in order to quantitatively account for both ordinary and anomalous contributions to the Hall effect. Under pressure, a drastic change in the field dependence of the Hall coefficient is found on crossing the QCEP. A possible Fermi surface change at Bm remains an open question.

Original languageEnglish
Article number104705
JournalJournal of the Physical Society of Japan
Issue number10
Publication statusPublished - 2013 Oct


  • Anomalous Hall effect
  • Ferromagnetism
  • Metamagnetism
  • Quantum critical end point
  • UCoAl


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