Ferromagnetic quantum critical endpoint in UCoAl

Dai Aoki, Tristan Combier, Valentin Taufour, Tatsuma D. Matsuda, Georg Knebel, Hisashi Kotegawa, Jacques Flouquet

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78 Citations (Scopus)


Resistivity and magnetostriction measurements were performed at high magnetic fields and under pressure on UCoAl. At ambient pressure, the 1st order metamagnetic transition at Hm ∼ 0.7 T from the paramagnetic ground state to the field-induced ferromagnetic state changes to a crossover at finite temperature T0 ∼ 11K. With increasing pressure, Hm linearly increases, while T0 decreases and is suppressed at the quantum critical endpoint (QCEP, Pqcep ∼ 1.5 GPa, Hm ∼ 7T). At higher pressure, the value of Hm identified as a crossover continuously increases, while a new anomaly appears above Pqcep at higher field H* in resistivity measurements. The field dependence of the effective mass (m*) obtained by resistivity and specific heat measurements exhibits a step-like drop at Hm at ambient pressure. With increasing pressure, it gradually changes into a peak structure and a sharp enhancement of m* is observed near the QCEP. Above Pqcep, the enhancement of m* is reduced, and a broad plateau is found between Hm and H*. We compare our results on UCoAl with those of the ferromagnetic superconductor UGe2 and the itinerant metamagnetic ruthenate Sr3 Ru2 O7.

Original languageEnglish
Article number094711
Journaljournal of the physical society of japan
Issue number9
Publication statusPublished - 2011 Sept
Externally publishedYes


  • Effective mass
  • Ferromagnetism
  • Metamagnetism
  • Quantum critical endpoint
  • UCoAl
  • UGe

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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