The transport properties of iron under Earths inner core conditions are essential input for the geophysical modelling but are poorly constrained experimentally. Here we show that the thermal and electrical conductivity of iron at those conditions rem
ains high even if the electron-electron-scattering (EES) is properly taken into account. This result is obtained by ab initio simulations taking into account consistently both thermal disorder and electronic correlations. Thermal disorder suppresses the non-Fermi-liquid behavior of the body-centered cubic iron phase, hence, reducing the EES; the total calculated thermal conductivity of this phase is 220 Wm$^{-1}$K$^{-1}$ with the EES reduction not exceeding 20%. The EES and electron-lattice scattering are intertwined resulting in breaking of the Matthiessens rule with increasing EES. In the hexagonal close-packed iron the EES is also not increased by thermal disorder and remains weak. Our main finding thus holds for the both likely iron phases in the inner core.
The electronic state and transport properties of hot dense iron are of the utmost importance to geophysics. Combining the density functional and dynamical mean field theories we study the impact of electron correlations on electrical and thermal resi
stivity of hexagonal close-packed $epsilon$-Fe at Earths core conditions. $epsilon$-Fe is found to behave as a nearly perfect Fermi liquid. The quadratic dependence of the scattering rate in Fermi liquids leads to a modification of the Wiedemann-Franz law with suppression of the thermal conductivity as compared to the electrical one. This significantly increases the electron-electron thermal resistivity which is found to be of comparable magnitude to the electron-phonon one. The implications of this effect on the dynamics of Earths core is discussed.
We report optical measurements demonstrating that the low-energy relaxation rate ($1/tau$) of the conduction electrons in Sr$_2$RuO$_4$ obeys scaling relations for its frequency ($omega$) and temperature ($T$) dependence in accordance with Fermi-liqu
id theory. In the thermal relaxation regime, $1/taupropto (hbaromega)^2 + (ppikB T)^2$ with $p=2$, and $omega/T$ scaling applies. Many-body electronic structure calculations using dynamical mean-field theory confirm the low-energy Fermi-liquid scaling, and provide quantitative understanding of the deviations from Fermi-liquid behavior at higher energy and temperature. The excess optical spectral weight in this regime provides evidence for strongly dispersing resilient quasiparticle excitations above the Fermi energy.
We have obtained the equilibrium volumes, bulk moduli, equations of state of the ferromagnetic cubic $alpha$ and paramagnetic hexagonal $epsilon$ phases of iron in close agreement with experiment using an ab initio dynamical mean-field theory approac
h. The local dynamical correlations are shown to be crucial for a successful description of the ground-state properties of paramagnetic $epsilon$-Fe. Moreover, they enhance the effective mass of the quasiparticles and reduce their lifetimes across the $alpha to epsilon$ transition leading to a step-wise increase of the resistivity, as observed in experiment. The calculated magnitude of the jump is significantly underestimated, which points to non-local correlations. The implications of our results for the superconductivity and non-Fermi-liquid behavior of $epsilon$-Fe are discussed.
We investigate the origin of the high Neel temperature recently found in Tc perovskites. The electronic structure in the magnetic state of SrTcO3 and its 3d analogue SrMnO3 is calculated within a framework combining band-structure and many-body metho
ds. In agreement with experiment, the Neel temperature of SrTcO3 is found to be four times larger than that of SrMnO3. We show that this is because the Tc-compound lies on the verge of the itinerant-to-localized transition, and also has a larger bandwidth, while the Mn-compound lies deeper into the localized side. For SrTcO3 we predict that the Neel temperature depends weakly on applied pressure, in clear violation of Blochs rule, signaling the complete breakdown of the localized picture.
Spin-entanglement of two electrons occupying two spatial regions -- domains -- is expressed in a compact form in terms of spin-spin correlation functions. The power of the formalism is demonstrated on several examples ranging from generation of entan
glement by scattering of two electrons to the entanglement of a pair of qubits represented by a double quantum dot coupled to leads. In the latter case the collapse of entanglement due to the Kondo effect is analyzed.
We calculate the zero temperature conductance and characteristic correlation functions of a molecule with a center of mass (CM) motion which modulates couplings to the leads. In the first model studied, the CM vibrational mode is simultaneously coupl
ed to the electron density on the molecule. The conductance is suppressed in regimes corresponding to non-integer occupancy of the molecule. In the second model, where the CM mode is not directly coupled to the electron density, the suppression of conductance is related to the dynamic breaking of the inversion symmetry.
