Coexistence of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi></mml:math>-state superconductivity and itinerant ferromagnetism

Fay, D.; Appel, J.

doi:10.1103/physrevb.22.3173

Cited by 338 publications

(379 citation statements)

References 24 publications

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“…This strongly suggests the resistivity is dominated by the scattering at ferromagnetic spin waves. It also shows the abundance of low-energy magnetic excitations on approaching the ferromagnetic quantum critical point near UCoGe, in line with the scenario of magnetically mediated superconductivity [4]. It will be highly interesting to investigate in detail the anisotropy of the magnetic fluctuations in the orthorhombic structure by magnetotransport experiments on single-crystalline samples.…”

Section: Discussionmentioning

confidence: 99%

Ferromagnetic order in U(Rh, Co)Ge

Huy

Visser

2009

Solid State Communications

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Abstract:We report the variation of ferromagnetic order in the pseudo-ternary compounds URh 1-x Co x Ge (0 ≤ x ≤ 1). Magnetization and transport data taken on polycrystalline samples show that the Curie temperature T C gradually increases with increasing Co content from a value of 9.5 K for URhGe to a maximum value of 20 K for x = 0.6 and then steadily decreases to 3 K for UCoGe. The magnetic interaction strength varies smoothly across the series. For all samples the electrical resistivity for T < T C follows the behaviour ρ = ρ 0 + AT 2 . The A coefficient is dominated by scattering at spin waves and is strongly enhanced for x = 0 and 1.

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Section: Discussionmentioning

confidence: 99%

Ferromagnetic order in U(Rh, Co)Ge

Huy

Visser

2009

Solid State Communications

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“…The bulk of the large theoretical literature [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50] dealing with this subject that evolved since then departs from an assumption dating back to the seminal work of Herz in the 1970's [51]. This involves the nature of the ultraviolet: at some relatively short time scale where the electron system has closely approached a Fermi-liquid the influence of the critical order parameter fluctuations become noticable.…”

Section: Introductionmentioning

confidence: 99%

BCS superconductivity in quantum critical metals

She

Zaanen

2009

Phys. Rev. B

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[file: qcbcs-arxiv2])We present a simple phenomenological scaling theory for the pairing instability of a quantum critical metal. It can be viewed as a minimal generalization of the classical Bardeen-Cooper-Schrieffer theory of superconductivity for normal Fermi-liquid metals. We assume that attractive interactions are induced in the fermion system by an external 'bosonic glue' that is strongly retarded. Resting on the small Migdal parameter, all the required information from the fermion system needed to address the superconductivity enters through the pairing susceptibility. Asserting that the normal state is a strongly interacting quantum critical state of fermions, the form of this susceptibility is governed by conformal invariance and one only has the scaling dimension of the pair operator as free parameter. Within this scaling framework, conventional BCS theory appears as the 'marginal' case but it is now easily generalized to the (ir)relevant scaling regimes. In the relevant regime an algebraic singularity takes over from the BCS logarithm with the obvious effect that the pairing instability becomes stronger. However, it is more surprising that this effect is strongest for small couplings and small Migdal parameters, highlighting an unanticipated important role of retardation. Using exact forms for the finite temperature pair susceptibility from 1+1D conformal field theory as models, we study the transition temperatures, finding that the gap to transition temperature ratio's are generically large compared to the BCS case, showing however an opposite trend as function of the coupling strength compared to conventional Migdal-Eliashberg theory. We show that our scaling theory naturally produces the superconducting 'domes' surrounding the quantum critical points, even when the coupling to the glue itself is not changing at all. We argue that hidden relations will exist between the location of the cross-over lines to the Fermi-liquids away from the quantum critical points , and the detailed form of the dome when the glue strength is independent of the zero temperature control parameter. Finally, we discuss the behavior of the orbital limited upper critical magnetic field as function of the zero temperature coupling constant. Compared to the variation of the transition temperature, the critical field might show a much stronger variation pending the value of the dynamical critical exponent.

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“…The intimate relationship between ferromagnetic (FM) fluctuations and superconductivity in UCoGe 5 , is a strong experimental suggestion of spintriplet superconductivity. In an itinerant FM superconductor with the presence of a large energy splitting between the majority and minority spin Fermi surfaces, exotic spin-triplet superconductivity is anticipated from a theoretical point of view 6 , in which pairing is between parallel spins within each spin Fermi surface. Since spintriplet superconductivity possesses multiple internal degrees of freedom, the identification of the spin state is a first step in understanding the spin-triplet superconductors.…”

Section: Introductionmentioning

confidence: 99%

Spin susceptibility in the superconducting state of the ferromagnetic superconductor UCoGe

et al. 2013

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In order to determine the superconducting paring state in the ferromagnetic superconductor UCoGe, 59 Co NMR Knight-shift, which is directly related to the microscopic spin susceptibility, was measured in the superconducting state under magnetic fields perpendicular to spontaneous magnetization axis: 59 K a,b . 59 K a,b shows to be constant, but does not decrease below a superconducting transition. These behaviors as well as the invariance of the internal field at the Co site in the superconducting state exclude the spin-singlet pairing, and can be interpreted with the equal-spin pairing state with a large exchange field along the c axis, which was studied by Mineev [Phys. Rev. B 81, 180504 (2010)].

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Coexistence ofp-state superconductivity and itinerant ferromagnetism

Cited by 338 publications

References 24 publications

Ferromagnetic order in U(Rh, Co)Ge

Ferromagnetic order in U(Rh, Co)Ge

BCS superconductivity in quantum critical metals

Spin susceptibility in the superconducting state of the ferromagnetic superconductor UCoGe

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