TY  - JOUR
A1  - Ciuchi, Sergio
A1  - Di Sante, Domenico
A1  - Dobrosavljević, Vladimir
A1  - Fratini, Simone
T1  - The origin of Mooij correlations in disordered metals
JF  - npj Quantum Materials
N2  - Sufficiently disordered metals display systematic deviations from the behavior predicted by semi-classical Boltzmann transport theory. Here the scattering events from impurities or thermal excitations can no longer be considered as additive-independent processes, as asserted by Matthiessen’s rule following from this picture. In the intermediate region between the regime of good conduction and that of insulation, one typically finds a change of sign of the temperature coefficient of resistivity, even at elevated temperature spanning ambient conditions, a phenomenology that was first identified by Mooij in 1973. Traditional weak coupling approaches to identify relevant corrections to the Boltzmann picture focused on long-distance interference effects such as “weak localization”, which are especially important in low dimensions (1D and 2D) and close to the zero-temperature limit. Here we formulate a strong-coupling approach to tackle the interplay of strong disorder and lattice deformations (phonons) in bulk three-dimensional metals at high temperatures. We identify a polaronic mechanism of strong disorder renormalization, which describes how a lattice locally responds to the relevant impurity potential. This mechanism, which quantitatively captures the Mooij regime, is physically distinct and unrelated to Anderson localization, but realizes early seminal ideas of Anderson himself, concerning the interplay of disorder and lattice deformations.
KW  - electronic properties and materials
KW  - phase transitions and critical phenomena
KW  - theory and computation
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-223148
VL  - 3
ER  - 
TY  - JOUR
A1  - Wagner, N.
A1  - Crippa, L.
A1  - Amaricci, A.
A1  - Hansmann, P.
A1  - Klett, M.
A1  - König, E. J.
A1  - Schäfer, T.
A1  - Di Sante, D.
A1  - Cano, J.
A1  - Millis, A. J.
A1  - Georges, A.
A1  - Sangiovanni, G.
T1  - Mott insulators with boundary zeros
JF  - Nature Communications
N2  - The topological classification of electronic band structures is based on symmetry properties of Bloch eigenstates of single-particle Hamiltonians. In parallel, topological field theory has opened the doors to the formulation and characterization of non-trivial phases of matter driven by strong electron-electron interaction. Even though important examples of topological Mott insulators have been constructed, the relevance of the underlying non-interacting band topology to the physics of the Mott phase has remained unexplored. Here, we show that the momentum structure of the Green’s function zeros defining the “Luttinger surface" provides a topological characterization of the Mott phase related, in the simplest description, to the one of the single-particle electronic dispersion. Considerations on the zeros lead to the prediction of new phenomena: a topological Mott insulator with an inverted gap for the bulk zeros must possess gapless zeros at the boundary, which behave as a form of “topological antimatter” annihilating conventional edge states. Placing band and Mott topological insulators in contact produces distinctive observable signatures at the interface, revealing the otherwise spectroscopically elusive Green’s function zeros.
KW  - electronic properties and materials
KW  - topological insulators
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-358150
VL  - 14
ER  - 
TY  - JOUR
A1  - Hausoel, A.
A1  - Karolak, M.
A1  - Şaşιoğlu, E.
A1  - Lichtenstein, A.
A1  - Held, K.
A1  - Katanin, A.
A1  - Toschi, A.
A1  - Sangiovanni, G.
T1  - Local magnetic moments in iron and nickel at ambient and Earth's core conditions
JF  - Nature Communications
N2  - Some Bravais lattices have a particular geometry that can slow down the motion of Bloch electrons by pre-localization due to the band-structure properties. Another known source of electronic localization in solids is the Coulomb repulsion in partially filled d or f orbitals, which leads to the formation of local magnetic moments. The combination of these two effects is usually considered of little relevance to strongly correlated materials. Here we show that it represents, instead, the underlying physical mechanism in two of the most important ferromagnets: nickel and iron. In nickel, the van Hove singularity has an unexpected impact on the magnetism. As a result, the electron–electron scattering rate is linear in temperature, in violation of the conventional Landau theory of metals. This is true even at Earth’s core pressures, at which iron is instead a good Fermi liquid. The importance of nickel in models of geomagnetism may have therefore to be reconsidered.
KW  - ferromagnetism
KW  - electronic properties and materials
KW  - magnetic properties and materials
KW  - nickel
KW  - iron
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170681
VL  - 8
IS  - 16062
ER  -