Multiorbital physics in Fermi liquids prone to magnetic order

Abstract

The interplay of spin-orbit coupling and strong electronic correlations is studied for the single-layer and the bilayer compound of the strontium ruthenate Ruddlesden-Popper series by a combination of first-principles band-structure theory with mean-field rotationally invariant slave bosons. At equilibrium strongly renormalized (spin-orbit-split) quasiparticle bands are traced and a thorough description of the low-energy regime for the nearly ferromagnetic bilayer system in accordance with experimental data is presented. The metamagnetic response of Sr 3 Ru 2 O 7 in finite magnetic field H is verified and a detailed analysis of the underlying correlated electronic structure provided. Intriguing multiorbital physics on both local and itinerant level, such as competing paramagnetic and diamagnetic contributions, is observed with important differences depending on the magneticfield angle θ with the crystallographic c axis.

TOMBO: All-electron mixed-basis approach to condensed matter physics

“…On the other hand, linear combination of atomic orbital (LCAO) approach enables us to treat core electrons. However, this approach has an intrinsic problem of incomplete basis set: there is a problem in applying approach has been extensively used to study electronic and/or phononic properties in bulk and/or surface systems [13][14][15][16][17][18][19]. Here, we reformulate the mixed-basis approach as an all-electron method, which enables us to study not only crystals but also molecules and clusters without introducing pseudo-potentials.…”

Mott transition, spin-orbit effects, and magnetism in Ca2RuO4

“…In the latter, it is the Coulomb-enhanced spin-orbit interaction, neglected in LDA+DMFT studies of the MIT so far, to actually induce the transition. Indeed, several works point to a relevant role of the spin-orbit coupling for the electronic structure of layered ruthenates [28][29][30][31][32]. To further complicate the picture, it was shown recently that, surprisingly, the effects of anisotropic Coulomb interactions-i.e., the terms with symmetry lower than O(3)-are crucial to reproduce the experimental Fermi surface of Sr 2 RuO 4 [30].…”

Formation of heavy d-electron quasiparticles in Sr3Ru2O7

“…The unusual physics of the bilayer ruthenate Sr 3 Ru 2 O 7 exemplifies some of the unsolved problems in condensed matter physics. Its rich phase diagram includes quantum criticality, magnetism and an electron nematic phase [1][2][3][4][5] and has generated considerable theoretical interest [6][7][8][9][10][11][12][13][14][15][16][17]. While there is no consensus on the precise microscopic origin of these properties, they are often associated with an instability of a heavy Fermi liquid resulting from strong correlations and the existence of a low-energy scale of unknown origin.…”