Dualism of the 5<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>f</mml:mi></mml:math>electrons of the ferromagnetic superconductor UGe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>as seen in magnetic, transport, and specific-heat data

Troć, R.; Gajek, Z.; Pikul, Adam

doi:10.1103/physrevb.86.224403

Cited by 54 publications

(65 citation statements)

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“…In conclusion, due to predominantly itinerant nature of f electrons in UGe 2 [26], it is very likely that any crystal-field derived multiplet structure is washed out and hence the value g f ≃ 2 should be regarded as realistic value. Nevertheless, the problem of double localized-itinerant nature of f -electrons [24,26] may arise as the system evolves with the increasing temperature, in comparison to the pressure evolution at low temperature studied in detail here.…”

Section: Resultsmentioning

confidence: 99%

“…The discussion of the dependence on (ii) has its justification in the not fully resolved nature of magnetism in heavy-fermion systems in general and UGe 2 in particular. Although it is assumed and widely accepted to be fully itinerant [2], there is evidence for a partially localized contribution [24,26]. In such case, the influence of the orbital effects and their coupling to the spin should have an influence on g f value.…”

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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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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Tricritical wings in UGe2: A microscopic interpretation

Abram

Wysokiński

Spałek

2016

Journal of Magnetism and Magnetic Materials

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“…It is justified because the higher multiplets are so high in energy that their population even in the room and ambient temperatures is negligibly small. Calculations of Troc et al [17] show that higher states make less than 10 percents contribution to the ground-state eigenfunction -the four terms of the ground-state eigenfunction associated with the 3 H 4 multiplet, shown in Table III in Ref. [17] gives 90% of the whole ground-state eigenfunction.…”

Section: Theoretical Outlinementioning

confidence: 99%

“…B publications [8,9] claim that in UGe 2 all f electrons are itinerant -in fact these publications were a direct motivation for this paper and its title, in particular. When we have been preparing this publication we have learnt about studies of Troc et al [17] with analysis of magnetic properties of UGe 2 with the 5f 2 (U 4+ ) configuration. A basic idea of studies of Troc et al for searching for the crystal-field-based explanation of magnetic properties is quite similar to the main idea of studies of Radwanski undertaken almost 30 years ago for rareearth and actinide intermetallics (later for 3d oxides): try to understand as much as possible by conventional physical interactions.…”

Section: Introductionmentioning

confidence: 99%

Three Localized f Electrons in UPd₂Al₃and in UGe₂Intermetallics

Radwański

Nalecz

Ropka³

2016

Acta Phys. Pol. A

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We have calculated the strength of the excitations between the crystal-field states which are in agreement with inelastic-neutron-scattering results. This agreement confirms the existence in the heavy-fermion superconductor UPd2Al3 the crystal-field electronic structure being the finger-print of the U 3+ ions with three localized f electrons forming strongly-correlated atomic-like quantum system 5f 3 . The ionic integrity and the low-energy crystal-field electronic structure is preserved in this metallic system in the meV scale as has been postulated in the Quantum Atomistic Solid State theory (QUASST). We provide preliminary results with the U 3+ ion in UGe2 showing the ground-state eigenfunction which reproduces the ordered magnetic-moment value of 1.48 µB. This moment is composed from the dominant orbital contribution (2.6 µB) and the opposite spin moment (1.12 µB).

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“…Uhlarz et al, 2004;Thessieu et al, 1995]. Unlike the localized 4f -electrons in the lanthanide series or the multiconfigurational 5f -electrons in some of the actinide elements [Booth et al, 2012;Troc et al, 2012] [Stoner, 1933], at a critical value of the density of states (DOS) and on-site repulsion, d-electrons can spontaneously split into spin-up and spin-down sub-bands, which leads to ferromagnetic ordering. Although the Stoner theory [Stoner, 1933] provides the grounds for understanding the itinerant ferromagnetic state, there are still questions left to be answered about the role of spin fluctuations and the quantum criticality in the itinerant ferromagnetic systems.…”

Section: Introductionmentioning

confidence: 99%

Development and exploration of potential routes of discovery of new superconductors

Lin

2013

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Dualism of the 5felectrons of the ferromagnetic superconductor UGe2as seen in magnetic, transport, and specific-heat data

Cited by 54 publications

References 56 publications

Tricritical wings in UGe2: A microscopic interpretation

Tricritical wings in UGe2: A microscopic interpretation

Three Localized f Electrons in UPd₂Al₃and in UGe₂Intermetallics

Development and exploration of potential routes of discovery of new superconductors

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Dualism of the 5felectrons of the ferromagnetic superconductor UGe2as seen in magnetic, transport, and specific-heat data

Cited by 54 publications

References 56 publications

Tricritical wings in UGe2: A microscopic interpretation

Tricritical wings in UGe2: A microscopic interpretation

Three Localized f Electrons in UPd2Al3and in UGe2Intermetallics

Development and exploration of potential routes of discovery of new superconductors

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Three Localized f Electrons in UPd₂Al₃and in UGe₂Intermetallics