Electronic and magnetic reconstructions in manganite superlattices

Abstract

We investigate the electronic reconstruction at the interface between ferromagnetic metallic (FM) and antiferromagnetic insulating (AFI) manganites in superlattices using a two-orbital doubleexchange model including superexchange interactions, Jahn-Teller lattice distortions, and long range Coulomb interactions. The magnetic and the transport properties critically depend on the thickness of the AFI layers. We focus on superlattices where the constituent parent manganites have the same electron density n = 0.6. The induced ferromagnetic moment in the AFI layers decreases monotonically with increasing layer width, and the electron-density profile and the magnetic structure in the center of the AFI layer gradually return to the bulk limit. The width of the AFI layers and the charge-transfer profile at the interfaces control the magnitude of the magnetoresistance and the metal-insulator transition of the FM/AFI superlattices.

Interfacial magnetic coupling in ultrathin all-manganite La0.7Sr0.3MnO3-TbMnO3 superlattices

“…[12][13][14][15] Epitaxial superlattices (SLs) of complex oxides give access to fascinating physical phenomena as a result of magnetic frustration, charge transfer, and orbital reconstruction across interfaces. [16][17][18][19][20][21][22] In particular, exchange bias, as a prototypical interfacial magnetic interaction between different spin orders, was reported in some manganite-based heterostructures and SLs. [23][24][25][26][27][28][29] Unlike CMR manganites such as La 0.7 Sr 0.3 MnO 3 (LSMO) where double exchange interactions lead to collinear ferromagnetism and metallic states, rare-earth manganite TbMnO 3 (TMO) offers multiferroic properties, coupling ferroelectric and magnetic orders.…”

Interfacial magnetism in manganite superlattices

“…α = e 2 /ǫat is the Coulomb interaction strength where ǫ and a are the dielectric constant and the lattice parameter, respectively. For the 2D case considered here α is approximately 0.1 18 .…”

“…The model and the method we employ have been elaborately discussed in Ref. 18. The model is given by…”

“…This method was already successfully applied in several earlier studies [21][22][23] . At each system sweep, with the additional H lrc term in the Hamiltonian, we solve for the Coulomb potentials φ i self-consistently until the electron density n i at each site is converged 18 . All physical quantities are averaged over the results for ten different 'samples' where each sample denotes a different initial realization of the classical variables.…”

“…Here a self-consistent solution of the Coulomb potentials φ i = αt j =i nj −Zj |Ri−Rj| is set up at the meanfield level [27][28][29] ; for details see Ref. 18. α = e 2 /ǫat is the Coulomb interaction strength where ǫ and a are the dielectric constant and the lattice parameter, respectively.…”