The Superconducting Ferromagnet UCoGe

Hanoi Advanced School of Science and Technology, Hanoi University of Technology, 1 Dai Co Viet, Hanoi, Vietnam
Journal of Low Temperature Physics (Impact Factor: 1.04). 10/2010; 161(1):134-147. DOI: 10.1007/s10909-010-0188-1
Source: arXiv

ABSTRACT The correlated metal UCoGe is a weak itinerant ferromagnet with a Curie temperature T
C=3K and a superconductor with a transition temperature T
s=0.6K. We review its basic thermal, magnetic—onthe macro and microscopic scale—and transport properties, as well as the
response to high pressure. The data unambiguously show that superconductivity and ferromagnetism coexist below T
s=0.6K and are carried by the same 5f electrons. We present evidence that UCoGe is a p-wave superconductor and argue that superconductivity is mediated by critical ferromagnetic spin fluctuations.

KeywordsSuperconducting ferromagnet-
p-wave superconductor-Magneticquantum critical point-Critical spin fluctuations

  • [Show abstract] [Hide abstract]
    ABSTRACT: We present an overview of unconventional phenomena arising close to ferromagnetic and ferroelectric quantum phase transitions. The applicability and potential breakdown of traditional field theories of quantum criticality and the emergence of a multiplicity of critical fields in particular will be discussed.
    Journal of Physics Conference Series 12/2012; 400(3):2048-. DOI:10.1088/1742-6596/400/3/032048
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Andreev reflection spectra dI/dV(V) of the magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4 have been investigated. Pronounced stimulation of superconductivity by an external magnetic field has been observed for the first time. The effect showed up as enhancement of the gap structure (and hence the gap itself) in the spectra and its shift towards higher voltages with an increasing field. In the intermediate fields the structure also behaved strangely: instead of the usual smooth decrease with an increasing field, the gap features dropped abruptly near the critical point Hc2. Of interest is also the abnormally high relative gap value 2Δ/kBTc ≈ 4 (as compared to conventional singlet superconductors) which was found for some contacts from a comparison of experimental spectra and the modified Blonder–Tinkham–Klapwijk theory. We attribute the features revealed in the point-contact spectroscopic investigations of Dy0.6Y0.4Rh3.85Ru0.15B4 in a magnetic field to the triplet-type Cooper pairing in the compound because only in this case one can expect the stimulation of superconductivity in the stationary magnetic fields up to ∼0.7Hc2.
    Low Temperature Physics 12/2012; 38(12). DOI:10.1063/1.4769209 · 0.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic fluctuations near to quantum criticality can have profound effects. They lead to characteristic scaling at high temperature which may ultimately give way to a reconstruction of the phase diagram and the formation of new phases at low temperatures. The ferromagnet UGe2 is unstable to p-wave superconducting order—an effect presaged by the superfluidity in 3He—whereas in CeFePO fluctuations drive the formation of spiral magnetic order. Here we develop a general quantum order-by-disorder description of these systems that encompasses both of these instabilities within a unified framework. This allows us to demonstrate that in fact these instabilities intertwine toform a pair density wave.
    Physical review. B, Condensed matter 03/2013; 87(12). DOI:10.1103/PhysRevB.87.121112 · 3.66 Impact Factor

Full-text (2 Sources)

Available from
May 23, 2014