2D Electron Gas with 100% Spin‐Polarization in the (LaMnO₃)₂/(SrTiO₃)₂ Superlattice under Uniaxial Strain

Abstract

By first‐principles calculations we investigate the structural, electronic, and magnetic properties of the (LaMnO3)2/(SrTiO3)2 superlattice. We find that a monoclinic C2h symmetry is energetically favorable and that the spins order ferromagnetically. Under both compressive and tensile uniaxial strain the electronic structure of the superlattice shows a half‐metallic character. In particular, a fully spin‐polarized two‐dimensional electron gas, which traces back to the Ti 3dxy orbitals, is achieved under compressive uniaxial strain.

Persistent half-metallic ferromagnetism in a (111)-oriented manganite superlattice

“…Despite their apparent simplicity, bulk materials exhibit a variety of ground states, driven by the strong interplay of different degrees of freedom [13][14][15][16][17]. The symmetry breaking at interfaces [18][19][20][21] leads to even more exciting phenomena, such as flat bands [22], anisotropic conductivity [23], magnetic anisotropy [24,25], exchange bias [26], spin-glass [27], electronic quantum confinement [28][29][30], unconventional superconductivity [31], topologically protected edge states [32,33], unexpected metallicity [34][35][36][37][38] and tunable quantum phase transitions [38][39][40].…”

Manganite/Cuprate Superlattice as Artificial Reentrant Spin Glass

“…One central issue is the lack of exact control of the spin order on the atomic scale, which is the prerequisite to the artificial modification of the glassy magnetic behavior. Recently, advances in fabricating high‐quality epitaxial thin film multilayers and superlattices (SLs) with unit‐cell‐level precision have led to a rapid surge of interest in the interface engineering of transition‐metal oxides, and such artificial heterostructures open new doors toward controlling the magnetic order in transition‐metal oxides.…”

“…For example, ferromagnetism was observed at the interfaces between two antiferromagnetic (AFM) materials . In LaMnO 3 /SrTiO 3 SL, charge transfer to the empty conduction band of titanate and orbital reconstruction cause the emergence of Ti 3+ ferromagnetism at the interface . In addition, the modification of octahedral rotation at the interface of oxide heterostructures was reported to tailor the ferromagnetism of ultrathin layers .…”

Magnetically controlled space charge capacitance at La1−xSrxMnO3/SrxLa1−xTiO3 interfaces

“…The possibility of stabilizing new phases at the epitaxial interfaces between dissimilar complex oxides has attracted great research interest in recent years not only for its fundamental importance, but also for the exciting opportunities of new functionalities and device architectures . A large variety of unexpected interface phenomena has already been discovered like a two‐dimensional electron gas between LaAlO 3 and SrTiO 3 epitaxial layers , conventional metallicity between non‐metals and super‐conductivity between non‐superconducting oxides .…”