Orbital selective directional conductor in the two-orbital Hubbard model

Abstract

Employing a recently developed many-body technique that allows for the incorporation of thermal effects, the rich phase diagram of a two dimensional two orbital (degenerate dxz and dyz) Hubbard model is presented varying temperature and the repulsion U . Our main result is the finding at intermediate U of a novel antiferromagnetic orbital selective state where an effective dimensional reduction renders one direction insulating and the other metallic. Possible realizations of this state are discussed. In addition we also study nematicity above the Néel temperature. After a careful finite-size scaling analysis the nematicity temperature window appears to survive in the bulk limit although it is very narrow.

Nonlocal correlations in the orbital selective Mott phase of a one-dimensional multiorbital Hubbard model

“…[1][2][3][4] On a theoretical front, this is a challenging problem due to a lack of non-perturbative methods for treating multiorbital Hubbard models at intermediate or strong couplings and on extended systems. Nevertheless, considerable progress has been made using mean-field-based approaches, [4][5][6][7][8][9][10][11][12][13][14][15][16] resulting in new concepts such as that of a Hund's metal 7,10,17,18 and the orbital-selective Mott phase (OSMP). 10,19 These concepts are central to our understanding the paradoxical appearance of both localized and itinerant characteristics in many multi-orbital systems 20,21 and bad metallic behavior in the presence of sizable electronic correlations.…”

Momentum distribution and non-Fermi-liquid behavior in low-doped two-orbital model: Finite-size cluster quantum Monte Carlo approach

“…Quasi one-dimensional "ladder" geometry was used in [8] for the study of the properties of the ground state of the two-orbital model by density matrix renormalization group approach. In the recent paper [9], the scheme "Monte-Carlo + meanfield", which has successfully approved itself in study of one-dimensional models, was generalized, and thermal properties of the two-orbital model were investigated. Exact numerical simulations of the two-orbital model, which include the method of exact diagonalization and the quantum Monte Carlo algorithms, are also limited in their applications.…”