On the microscopic model of Fe and Ni: the possible breakdown of the ferromagnetic fermi-liquid picture

Irkhin, V. Yu.; Katsnelson, M. I.; Trefilov, A. V.

doi:10.1088/0953-8984/5/46/014

Cited by 38 publications

(16 citation statements)

References 41 publications

(7 reference statements)

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“…Thus, the opening of a soft gap observed here has an origin different from the electron-electron Coulomb repulsion observed in other systems [17]. The exponent of 3/2 in SDOS suggests strong influence of electron-magnon coupling on the electronic structure [18] presumably responsible for the ferromanetic ground state.…”

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confidence: 50%

Origin of Charge Density Wave Formation in Insulators from a High Resolution Photoemission Study ofBaIrO3

et al. 2005

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We investigate the origin of charge density wave (CDW) formation in insulators by studying BaIrO3 using high-resolution (1.4 meV) photoemission spectroscopy. The spectra reveal the existence of localized density of states at the Fermi level, E(F), in the vicinity of room temperature. These localized states are found to vanish as the temperature is lowered, thereby, opening a soft gap at E(F), as a consequence of CDW transition. In addition, the energy dependence of the spectral density of states reveals the importance of magnetic interactions, rather than well-known Coulomb repulsion effect, in determining the electronic structure thereby implying a close relationship between ferromagnetism and CDW observed in this compound. Also, Ba core level spectra surprisingly exhibit an unusual behavior prior to CDW transition.

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confidence: 50%

Origin of Charge Density Wave Formation in Insulators from a High Resolution Photoemission Study ofBaIrO3

et al. 2005

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“…The decay leading to a t ↑ 2g final hole with m v = ±1 (d xz ,d yz ) gives the strongest contribution, making a distinction between different orbitals in the DOS around the absorber ion. Indeed, considering the localized na-ture of the recombination, such DOS unravels the orbital character of the decaying states better than the DOS of the whole cluster, revealing narrow and prounounced peaks from different orbitals of the two irreducible representations in the spin up main peak, reminding of Van Hove singularities in the extended electronic structure 67,68 . Angular momentum conservation rules then dictate a Y ↓ 33 emitted wave, with strong intensity reduction along the quantization axis, similarly to the one expected in direct photoemission from a dshell (Clebsch-Gordan coefficients indeed give the highest probablity for a final m = ±3 state generated by photon absorption at the m v = ±2 states) and in line with previous reports on aligned f ±3 emitted waves for different compounds 32 .…”

Section: Resultsmentioning

confidence: 99%

Fingerprints of entangled spin and orbital physics in itinerant ferromagnets via angle-resolved resonant photoemission

Pieve

2016

Phys. Rev. B

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A novel method for mapping the local spin and orbital nature of the ground state of a system via corresponding flip excitations in both sectors is proposed based on angle resolved resonant photoemission and related diffraction patterns, presented here for the first time via an ab-initio modified one-step theory of photoemission. The analysis is done on the paradigmatic weak itinerant ferromagnet bcc Fe, whose magnetism, seen as a correlation phenomenon given by the coexistence of localized moments and itinerant electrons, and the non-Fermi liquid behaviour at ambient and extreme conditions both remain unclear. The results offer a real space imaging of local pure spin flip and entangled spin flip-orbital flip excitations (even at energies where spin flip transitions are hidden in quasiparticle peaks) and of chiral, vortex-like wavefronts of excited electrons, depending on the orbital character of the bands and the direction of the local magnetic moment. Such effects, mediated by the hole polarization, make resonant photoemission a promising tool to perform a full tomography of the local magnetic properties of a system with a high sensitivity to localization/correlation, even in itinerant or macroscopically non magnetic systems.

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“…Another important aspect is the interplay between the local Coulomb interaction, characterized by large J H , and crystal-field splitting of Fe 3d states. This interplay is particularly striking in the bcc α phase, where the partial e g density-of-states (DOS) features a large peak pinned at the Fermi level due to a van Hove singularity [25,26]. Correspondingly, this high DOS at the Fermi level in nonmagnetic α-Fe explains its tendency towards the ferromagnetism in accordance with the Stoner criterion.…”

Section: Introductionmentioning

confidence: 87%

Electronic correlations in dense iron: from moderate pressure to Earth’s core conditions

Pourovskii

2019

J. Phys.: Condens. Matter

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We discuss the role of dynamical many-electron effects in the physics of iron and ironrich solid alloys under applied pressure on the basis of recent ab initio studies employing the dynamical mean-field theory (DMFT). We review in details two particularly interesting regimes: first, a moderate pressure range up to 60 GPa and, second, the ultra-high pressure of about 360 GPa expected inside the solid inner core of Earth.Electronic correlations in iron under the moderate pressure of several tens GPa are discussed in the first section. DMFT-based methods predict an enhancement of electronic correlations at the pressure-induced body-centered cubic α → hexagonal close-packed phase transition. In particular, the electronic effective mass, scattering rate and electron-electron contribution to the electrical resistivity undergo a step-wise increase at the transition point. One also finds a significant many-body correction to the -Fe equation of state, thus clarifying the origin of discrepancies between previous DFT studies and experiment. An electronic topological transition is predicted to be induced in -Fe by many-electron effects; its experimental signatures are analyzed.Next section focuses on the geophysically relevant pressure-temperature regime of the Earth's inner core (EIC) corresponding to the extreme pressure of 360 GPa combined with temperatures up to 6000 K. The three iron allotropes (α, and face-centered-cubic γ) previously proposed as possible stable phases at such conditions are found to exhibit qualitatively different many-electron effects as evidenced by a strongly non-Fermi-liquid metallic state of α-Fe and an almost perfect Fermi liquid in the case of -Fe. A recent active discussion on the electronic state and transport properties of -Fe at the EIC conditions is reviewed in details. Estimations for the dynamical many-electron contribution to the relative phase stability are presented. We also discuss the impact of a Ni admixture, which is expected to be present in the core matter. We conclude by outlining some limitation of the present DMFTbased framework relevant for studies of iron-base systems as well as perspective directions for further development.

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On the microscopic model of Fe and Ni: the possible breakdown of the ferromagnetic fermi-liquid picture

Cited by 38 publications

References 41 publications

Origin of Charge Density Wave Formation in Insulators from a High Resolution Photoemission Study ofBaIrO3

Origin of Charge Density Wave Formation in Insulators from a High Resolution Photoemission Study ofBaIrO3

Fingerprints of entangled spin and orbital physics in itinerant ferromagnets via angle-resolved resonant photoemission

Electronic correlations in dense iron: from moderate pressure to Earth’s core conditions

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