Quantum fluctuation driven first-order phase transition in weak ferromagnetic metals

• Published in: Philosophical magazine (Abingdon, England) England), 2005-06, Vol.85 (16), p.1755-1763
• Main Authors: Jackiewicz, Jason A., Bedell, Kevin S.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.); Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Other ferromagnetic metals and alloys; Physics; Studies of specific magnetic materials
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430500040720

In a local Fermi liquid (LFL), we show that there is a line of weak first-order phase transitions between the ferromagnetic and paramagnetic phases due to purely quantum fluctuations. We predict that an instability towards superconductivity is only possible in the ferromagnetic state. At T = 0 we find a point on the phase diagram where all three phases meet and we call this a quantum triple point (QTP). A simple application of the Gibbs phase rule shows that only these three phases can meet at the QTP. This provides a natural explanation of the absence of superconductivity at this point coming from the paramagnetic side of the phase diagram, as observed in the recently discovered ferromagnetic superconductor, UGe 2 .