Near-room-temperature control of magnetization in field effect devices based on La0.67Sr0.33MnO3 thin films

Abstract

The control of the magnetization in ferromagnetic layers via electric fields is a hot topic in view of applications to the next generation of spintronic devices, where writing the magnetic information through current lines could be replaced by electric writing. Mixed valence manganites are good candidates for such a purpose because they present an intriguing coupling between ferromagnetism and charge ordering/doping which can be tuned by the application of an electric field. Here we present results on the near-room temperature control of the magnetization of optimally doped La0.67Sr0.33MnO3 ultrathin films in vertical field effect devices, where they act as top or bottom electrodes. In the latter case a slight decrease in the Curie temperature 5 K is observed after application of 5107 V/m, i.e., the maximum field preventing electric breakdown, compatible with the induced variation in the charge density and mixed valence within the Thomas Fermi screening length. These results indicate that electric fields achievable in vertical field effect devices, of the same entity of interfacial fields originating from differences in the work function in heterostructures, have only minor influence on the magnetic properties of optimally doped ultrathin La0.67Sr0.33MnO3 films

Ferroelectric capped magnetization in multiferroic PZT/LSMO tunnel junctions

“…19 In most investigations, the active layers of heterostructures are much thicker than the dead layers; only a few reports on multiferroic heterostructure field-effect devices even mention the existence of dead layers. Brivio et al 20 report the absence of any electric field effect on magnetic modulation of 3-nm LSMO thin film when it was bottom-gated with non-polar SrTiO 3 (STO) thin film, however, the effect was significant when applied from the top side. They proposed that this effect was due to the presence of a dead layer at the bottom STO/LSMO interface.…”

Hybrid supercapacitors for reversible control of magnetism

“…Typically, two possible charging mechanisms may occur at solid/solid or solid/liquid interfaces. The first involves non-faradaic electrostatic doping, where the charge carriers are electrostatically separated at the interface between a magnetic material and a ferroelectric78910, a dielectric11 or an electrolyte1213, in analogy to a parallel plate capacitor. The second implies faradaic electrochemical doping, where redox reactions with exchange of charge carriers14151617 occur across the interface between a magnetic material and a different chemical species, resembling the behaviour of an electrochemical cell.…”

Polarization screening-induced magnetic phase gradients at complex oxide interfaces

“…Moreover, it is known that a suppression of ferroelectric polarization may occur at interfaces, but it is unclear how this may play a role in the LSMO/PZT system 17 . Recently, Lu et al 18 have proposed a theoretical mechanism whereby charge-transfer screening electrostatically dopes an interface region of the LSMO into a paramagnetic insulating state, which might explain the larger screening lengths we and others have measured 16,19 . More insight is clearly needed into local ferroelectric polarization and the presence of such a 'doping-induced double layer,' which would have fundamental implications for oxide-based electronics.…”