Interface Local Magnetic Moment and Its Near Periodic Modulation in Oxide SrRuO3|LaAlO3 Heterojunctions: An Ab Initio Investigation

Using density functional theory, the interface local magnetic moment and its variation are explored in SrRuO
₃
|LaAlO
₃
|vacuum (001) heterostructures with increasing number of LaAlO
₃
unit cells. The computed magnetic moment projected on interface planes is found to modulate nearly periodically as the number of LaAlO
₃
unit cells is increased in SrRuO
₃
|LaAlO
₃
|vacuum structure. The magnetic moment localized at the interface RuO
₂
plane shifts from a lower value of ~0.7 μ
_B
to a higher value of ~1.35 μ
_B
and changes by ~42% as LaAlO
₃
changes from non-stoichiometric to stoichiometric with increase in its thickness. However, the magnitude shifts from higher to lower value as LaAlO
₃
changes from stoichiometric to non-stoichiometric with further increase in thickness. The large variation and nearly periodic modulation of magnetic moment localized at the interface with increasing LaAlO
₃
thickness arise due to spin-dependent screening of effective total charge of LaAlO
₃
film by accumulated free carriers at the interface in heterostructure. The modulation of interface local magnetic moment using ultrathin LaAlO
₃
film at the oxide heterointerfaces can be exploited as an additional functionality, in conjunction with those reported recently such as control of band alignment and enhancement of the electric conductivity at the interface.