Pressure-temperature phase diagram of the heavy-electron superconductor URu2 Si2

H. Amitsuka, K. Matsuda, I. Kawasaki, K. Tenya, M. Yokoyama, C. Sekine, N. Tateiwa, T. C. Kobayashi, S. Kawarazaki, H. Yoshizawa

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143 Citations (Scopus)


The pressure-temperature phase diagram of the heavy-electron superconductor URu2 Si2 has been reinvestigated by AC-susceptibility and elastic neutron-scattering (NS) measurements performed on a small single-crystalline rod (2 mm in diameter, 6 mm in length) in a Cu-Be clamp-type high-pressure cell (P < 1.1 GPa). At ambient pressure, this sample shows the weakest antiferromagnetic (AF) Bragg reflections reported so far, corresponding to the volume-averaged staggered moment of μo ∼ 0.011 μB / U. Under applied pressure, the AF scattering intensity exhibits a sharp increase at P ∼ 0.7 GPa at low temperatures. The saturation value of the AF scattering intensity above 0.7 GPa corresponds to μo ∼ 0.41 μB / U, which is in good agreement with that (∼ 0.39 μB / U) observed above 1.5 GPa in our previous NS measurements. The superconductivity is dramatically suppressed by the evolution of AF phase, indicating that the superconducting state coexists only with the hidden order phase. The presence of parasitic ferro- and/or antiferromagnetic phases with transition temperatures T1{star, open} = 120 (5), T2{star, open} = 36 (3) and T3{star, open} = 16.5 (5) K and their relationship to the low-T ordered phases are also discussed.

Original languageEnglish
Pages (from-to)214-220
Number of pages7
JournalJournal of Magnetism and Magnetic Materials
Issue number2 SUPPL. PART 1
Publication statusPublished - Mar 2007


  • Antiferromagnetism
  • Hidden order
  • Hydrostatic pressure
  • Superconductivity
  • URu Si

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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