Electronic and magnetic properties in strongly correlated heterostructures

TL;DR

This paper theoretically investigates the complex interplay of magnetism and charge distribution in heterostructures like SrTiO3/LaTiO3, revealing multiple ordered phases and magnetic transitions driven by strong correlations.

Contribution

It introduces a mean-field analysis of a generalized Hubbard model for heterostructures, uncovering new magnetic and charge-ordered phases and their transitions under external fields.

Findings

Discovery of canted antiferromagnetic states near interfaces.

Identification of checkerboard charge order stabilized by Coulomb interactions.

Observation of first-order metamagnetic and reentrant charge-order transitions.

Abstract

We present a theoretical study of a model heterostructure for a Mott-insulator sandwiched between two band insulators, such as SrTiO3/LaTiO3. Particular emphasis is given on the interplay between magnetism and inhomogeneous charge distributions. Our mean-field analysis of the generalized Hubbard model displays numerous ordered phases in the ground-state phase diagram. In particular, we find a canted antiferromagnetic state near the interface when antiferromagnetic-ordering exists inside the Mott insulator. A checkerboard charge-ordering proposed previously is also stabilized for large long-range Coulomb interactions. Regarding its origin we also point out the importance of interlayer spin-mediated interactions. It is further shown that such a strong spin-charge coupling gives rise to pronounced magnetic/charge order phase transitions in external magnetic fields: a firstorder metamagnetic transition and a reentrant charge-order transition with checkerboard pattern. The mechanisms stabilizing these intriguing phases are explored through a detailed analysis of the physical quantities with special focus on the spin-charge interplay.