Coexistence of spin-triplet superconductivity with magnetism within a single mechanism for orbitally degenerate correlated electrons: statistically consistent Gutzwiller approximation

Zegrodnik, M.; Spałek, J.; Bünemann, Jörg

doi:10.1088/1367-2630/15/7/073050

Cited by 28 publications

(47 citation statements)

References 51 publications

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“…The effective attraction for Cooper pairs can be understood from the imbalance of the Coulomb interactions [14,[33][34][35]. To see this, let us consider the situation with two electrons on one lattice site.…”

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confidence: 99%

Superconductivity from Emerging Magnetic Moments

2015

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Multiorbital Hubbard models are shown to exhibit a spatially isotropic spin-triplet superconducting phase, where equal-spin electrons in different local orbitals are paired. This superconducting state is stabilized in the spin-freezing crossover regime, where local moments emerge in the metal phase, and the pairing is substantially assisted by spin anisotropy. The phase diagram features a superconducting dome below a non-Fermi-liquid metallic region and next to a magnetically ordered phase. We suggest that this type of fluctuating-moment-induced superconductivity, which is not originating from fluctuations near a quantum critical point, may be realized in spin-triplet superconductors such as strontium ruthenates and uranium compounds.

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confidence: 99%

Superconductivity from Emerging Magnetic Moments

2015

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“…To determine the stability of SC inside the FM phase, the present approach should be extended to account for the Hund's rule interaction explicitly, which can be crucial for the formation of the unconventional triplet SC [6,7,28,29]. If this is the case, it can be triggered even by a purely repulsive Coulomb interaction in conjunction with the residual Hund's rule coupling, as discussed in Refs.…”

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Ferromagnetism inUGe2: A microscopic model

2014

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The Anderson lattice model is used to explain the principal features of the heavy fermion compound UGe 2 by means of the generalized Gutzwiller approach (the statistically consistent Gutzwiller approximation method). This microscopic approach successfully reproduces the magnetic and electronic properties of this material, in qualitative agreement with experimental findings from magnetization measurements, neutron scattering, and de Haas-van Alphen oscillations. Most importantly, it explains the appearance, sequence, character, and evolution in an applied magnetic field of the observed in UGe 2 ferromagnetic and paramagnetic phases as an effect of a competition between the f -f electron Coulomb interaction energy and f -conduction electron hybridization.

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“…The proposed quantum critical point is of Lifshitz type as it separates states with two distinct Fermi-surface topologies. Quantum critical fluctuations or the residual f -f Hund's rule interaction (neglected here) can become the possible source of the spin-triplet superconductivity [37][38][39][40][41]. A detailed and quantitative discussion of the pairing requires a separate analysis.…”

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Tricritical wings in UGe2: A microscopic interpretation

Abram

Wysokiński

Spałek

2016

Journal of Magnetism and Magnetic Materials

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In the present work we analyze the second order transition line that connect the tricritical point and the quantum critical ending point on the temperature-magnetic-field plane in UGe2. For the microscopic modeling we employ the Anderson lattice model recently shown to provide a fairly complete description of the full magnetic phase diagram of UGe2 including all the criticalities. The shape of the so-called tricritical wings, i.e. surfaces of the first-order transitions, previously reported by us to quantitatively agree with the experimental data, is investigated here with respect to the change of the total filling and the Landé factor for f electrons which can differ from the free electron value. The analysis of the total filling dependence demonstrates sensitivity of our prediction when the respective positions of the critical ending point at the metamagnetic transition and tricritical point are mismatched as compared to the experiment. I. MOTIVATION AND OVERVIEWQuantum critical phenomena have captured general attention due to their unique singular properties observed at low temperature (T → 0) and near the quantum critical point (QCP) which is frequently accompanied by the unconventional superconductivity (SC) [1]. From this perspective, f -electron compound UGe 2 is a system with phase diagram comprising coexistence of spin-triplet SC and ferromagnetism (FM) [2-6], as well as an abundance of critical points (CP), either of quantum and classical nature [7]. Experimental studies among others have revealed existence of the two characteristic classical CPs in the absence of the field (cf. Fig. 1): (i) the critical ending point (CEP) at 7K at the metamagnetic transition separating strong (FM2) and weak magnetization (FM1) regions [8][9][10], and (ii) the tricritical point (TCP) at the FM to paramagnetic (PM) phase transition located at T = 24 K. Additionally, with the applied magnetic field the second order transition line starting from TCP can be followed to T = 0 where it is expected to terminate in a quantum critical ending point (QCEP) [9,10]. In effect the magnetic phase boundaries in UGe 2 reflects so-called tricritical wing shape.Such complex magnetic phase diagram with all the above criticalities, both classical and quantum, is particularly challenging in terms of theoretical modeling. One of the first approaches, based on the single-band model describing tricritical wings, was the work by Belitz, et al. [11]. However, the microscopic description of the magnetic phase diagram with all the CPs including also CEP at the metamagnetic transition, as observed in UGe 2 , has been missing until our recent works [13,14].Our analysis is based on the (two-orbital) Anderson * marcin.abram@uj.edu.pl † marcin.wysokinski@uj.edu.pl ‡ ufspalek@if.uj.edu.pl lattice model (ALM) [13,14], often referred to as the periodic Anderson model. Findings for UGe 2 , both from first principle calculations and experiments are: the quasitwo-dimensional character of the Fermi surface [15], a uniaxial anisotropy for magnetization [16], ...

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Coexistence of spin-triplet superconductivity with magnetism within a single mechanism for orbitally degenerate correlated electrons: statistically consistent Gutzwiller approximation

Cited by 28 publications

References 51 publications

Superconductivity from Emerging Magnetic Moments

Superconductivity from Emerging Magnetic Moments

Ferromagnetism inUGe2: A microscopic model

Tricritical wings in UGe2: A microscopic interpretation

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