Magnetic properties of almost localized fermions revisited: spin dependent masses and quantum critical behavior

Abstract

The magnetic properties of almost localized (heavy) quasiparticles have been a subject of renewed interest in recent years. This is caused by the discovery of spin dependent masses predicted by us some time ago, as well as quantum critical behavior at the metal -insulator boundary. We discuss those phenomena, as well as metamagnetic behavior. These phenomena are discussed by regarding Gutzwiller approach (in the slave-boson version) as the mean-field approach to the correlated electron systems.

Unconventional topological superconductivity and phase diagram for an effective two-orbital model as applied to twisted bilayer graphene

“…It is established that d + id pairing symmetry might render the system a topological SC. 29 For the model (6) we have explicitly computed the Chern number by the efficient method of Brillouin-zone triangulation 30 with the result ±4, depending on the direction of phase winding of the d+id order parameter. In this situation, a distinct set of topologically-protected edge states is expected for finite-size sample.…”

“…This is because in the systems such as heavy fermions, 1 high-temperature superconductors (SC), 2 or selected atomic systems in optical lattice, 3 the interparticle interaction energy can exceed by far the single-particle (kinetic, band) energy. In that situation, specific phenomena induced by the interelectronic correlations occur, such as the Mott or the Mott-Hubbard localization, 4 unconventional superconductivity (SC) associated with real-space pairing, 5 as well as specific magnetic behavior, such as metamagnetic transition to localized state, spin-dependent masses of quasiparticles, 6 and quantum critical behavior. 7 In this context, the recent discovery of SC and the concomitant Mott insulating (MI) behavior [8][9][10] of twisted bilayer graphene (TBG) provides a model situation for studying phenomena ascribed to high-temperature SC.…”

Fermi Surface Properties, Metamagnetic Transition and Quantum Phase Transition of CeRu2Si2 and Its Alloys Probed by the dHvA Effect

“…106,107,111,[133][134][135][136][137][138][139][140][141] The spin dependence has been discussed also theoretically. [142][143][144][145][146] The spin dependence is observed when the f electron is in a polarized state under magnetic fields. It seems that the spin dependence is more significant when the polarization is larger.…”

Extended Hubbard model with renormalized Wannier wave functions in the correlated state III: Statistically consistent Gutzwiller approximation and the metallization of atomic solid hydrogen

“…Finally, one can extend our analysis to nonzero temperatures in a straightforward manner, starting from the free-energy functional (9). This should be carried out separately and the results can be compared with GA results providing the first-order line ending in a classical critical point, as well as the reentrant metallic behavior [19,20,27].…”

“…We observe the two important features. First, the quasiparticle mass is spin-independent in this halffilled band case, unlike in the non-half-filled case [19,20]. Also, the mass enhancement due to the correlations increases in SGA relatively slowly compared to that in the parametrized GA approach [21] as R → R c − 0.…”