Quantum criticality in NbFe<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>induced by zero carrier velocity

Neal, Brian; Ylvisaker, E. R.; Pickett, Warren E.

doi:10.1103/physrevb.84.085133

Cited by 22 publications

(16 citation statements)

References 33 publications

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“…It may be possible to access these band critical points that have vanishing quasiparticle velocities via small perturbations due to impurities, doping, or changes in structural parameters. The role of such band critical points in quantum criticality has been emphasized recently [12], and similar physics may be relevant in this system.…”

Section: Resultsmentioning

confidence: 75%

Unconventional sign-changing superconductivity near quantum criticality in YFe2Ge2

Subedi

2014

Phys. Rev. B

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I present the results of first principles calculations of the electronic structure and magnetic interactions for the recently discovered superconductor YFe 2 Ge 2 and use them to identify the possible nature of superconductivity and quantum criticality in this compound. I find that the Fe 3d derived states near the Fermi level show a rich structure with the presence of both linearly dispersive and heavy bands. The Fermi surface exhibits nesting between hole and electron sheets that manifests as a peak in the susceptibility at (1/2,1/2). The antiferromagnetic spin fluctuations associated with this peak may be responsible for mediating the superconductivity in this compound resulting in a s ± state similar to that of the previously discovered iron-based superconductors. I also find that various magnetic orderings are almost degenerate in energy, which indicates that the proximity to quantum criticality is due to competing magnetic interactions.

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Section: Resultsmentioning

confidence: 75%

Unconventional sign-changing superconductivity near quantum criticality in YFe2Ge2

Subedi

2014

Phys. Rev. B

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“…19). The fact that both iron and niobium-rich samples are FM at low temperature has been linked to the peculiar electronic structure of this material (Alam and Johnson, 2011;Neal et al, 2011;Subedi and Singh, 2010;Tompsett et al, 2010). Part of the phase diagram can also be reproduced by applying hydrostatic pressure : Starting with a FM sample with y = 0.015, increasing pressure is equivalent to moving the system to the left in the phase diagram of Fig.…”

Section: Simple Ferromagnetsmentioning

confidence: 99%

Metallic quantum ferromagnets

et al. 2016

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We give an overview of quantum phase transitions (QPTs) in metallic ferromagnets, discussing both experimental and theoretical aspects. These QPTs can be classified with respect to the presence and strength of quenched disorder: Clean systems generically show a discontinuous, or first-order, QPT from a ferromagnetic to a paramagnetic state as a function of some control parameter, as predicted by theory. Disordered systems are much more complicated, depending on the disorder strength and the distance from the QPT. In many disordered materials the QPT is continuous, or second order, and Griffiths-phase effects coexist with QPT singularities near the transition. In other systems the transition from the ferromagnetic state at low temperatures is to a different type of long-range order, such as an antiferromagnetic or a spin-density-wave state. In still other materials a transition to a state with glass-like spin dynamics is suspected. The review provides a comprehensive discussion of the current understanding of these various transitions, and of the relation between experiment and theory.

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“…In the Nb 1−y Fe 2+y composition series, the magnetic state depends sensitively on composition [8][9][10][11] . Nbrich (y < −0.02) and Fe-rich (y > 0.005) Nb 1−y Fe 2+y are weakly ferromagnetic (FM) at low temperature, which may be attributed to changes in the electronic structure [12][13][14][15] . At intermediate compositions y ≃ 0 in Nb 1−y Fe 2+y , however, samples are not FM, although they still appear to order magnetically as shown by susceptibility measurements, and which was tentatively interpreted as a SDW state.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic study of metallic magnetism in single-crystallineNb1−yFe2+y

et al. 2015

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We have investigated single crystals and polycrystals from the series Nb1−yFe2+y, −0.004 ≤ y ≤ 0.018 by electron spin resonance, muon spin relaxation and Mössbauer spectroscopy. Our data establish that at lowest temperatures all samples exhibit bulk magnetic order. Slight Feexcess induces low-moment ferromagnetism, consistent with bulk magnetometry, while Nb-rich and stoichiometric NbFe2 display spin density wave order with small magnetic moment amplitudes of the order ∼ 0.001 − 0.01µB /Fe. This provides microscopic evidence for a modulated magnetic state on the border of ferromagnetism in NbFe2.

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Quantum criticality in NbFe2induced by zero carrier velocity

Cited by 22 publications

References 33 publications

Unconventional sign-changing superconductivity near quantum criticality in YFe2Ge2

Unconventional sign-changing superconductivity near quantum criticality in YFe2Ge2

Metallic quantum ferromagnets

Spectroscopic study of metallic magnetism in single-crystallineNb1−yFe2+y

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