Spinterface Effects in Hybrid La_0.7Sr_0.3MnO₃/SrTiO₃/C₆₀/Co Magnetic Tunnel Junctions

Abstract

The orbital hybridization at the Co/C 60 interface has proved to strongly enhance the magnetic anisotropy of the cobalt layer, promoting such hybrid systems as appealing components for sensing and memory devices. Correspondingly, the same hybridization induces substantial variations in the ability of Co/C 60 interface to support spin polarized currents and can bring out spin filtering effect.The knowledge of the effects at both sides shall allow for a better and more complete understanding of interfacial physics. In this paper we investigate the Co/C 60 bilayer in the role of spin polarized electrode in the La 0.7 Sr 0.3 MnO 3 /SrTiO 3 /C 60 /Co configuration, thus substituting the bare Co electrode in the well-known La 0.7 Sr 0.3 MnO 3 /SrTiO 3 /Co magnetic tunnel junction. The study revealed that the spin polarization (SP) of the tunneling currents escaping from the Co/C 60 electrode is generally negative, i.e. inverted with respect to the expected SP of the Co electrode. The observed sign of the spin polarization was confirmed via DFT calculations by considering the hybridization between cobalt and molecular orbitals.

Enhancement of Magnetic Stability in Antiferromagnetic CoO Films by Adsorption of Organic Molecules

“…The spinterface formation affects the spin properties of both interface components. For example, it is responsible for the generation of spin polarization in the molecules , and for the change of the magnetic behavior of the ferromagnetic (FM) layer. , An emblematic example is provided by the adsorption of buckminster fullerene molecule (C 60 ) onto a cobalt (Co) layer: as a result of hybridization between metallic d z 2 and carbon p z orbitals, the Co layer acquires an out-of-plane interfacial anisotropy that is able to give rise to a spin reorientation transition from in-plane to out-of-plane magnetization. Hybridization effects have been widely investigated both theoretically and experimentally considering FM metallic layers − while the adsorption and coupling of molecules on oxide surfaces with antiferromagnetic (AF) order have not been elucidated yet. − The investigation of such effects on systems featuring complex spin configurations allows thus to enrich our fundamental knowledge of spinterfaces and also to explore the possibility of tuning with molecules some intrinsic AF properties such as ultra-fast magnetization dynamics and magnon-mediated spin transport .…”

“…The spinterface formation affects the spin properties of both interface components. For example, it is responsible for the generation of spin polarization in the molecules 4 , 5 and for the change of the magnetic behavior of the ferromagnetic (FM) layer. 6 , 7 An emblematic example is provided by the adsorption of buckminster fullerene molecule (C 60 ) onto a cobalt (Co) layer: 7 as a result of hybridization between metallic d z 2 and carbon p z orbitals, the Co layer acquires an out-of-plane interfacial anisotropy that is able to give rise to a spin reorientation transition from in-plane to out-of-plane magnetization.…”