Co-Doped(La,Sr)TiO3−δ: A High Curie Temperature Diluted Magnetic System with Large Spin Polarization

Abstract

We report on tunneling magnetoresistance (TMR) experiments that demonstrate the existence of a significant spin polarization in Co-doped (La, Sr)TiO(3-delta) (Co-LSTO), a ferromagnetic diluted magnetic oxide system (DMOS) with high Curie temperature. These TMR experiments have been performed on magnetic tunnel junctions associating Co-LSTO and Co electrodes. Extensive structural analysis of Co-LSTO combining high-resolution transmission electron microscopy and Auger electron spectroscopy excluded the presence of Co clusters in the Co-LSTO layer and thus, the measured ferromagnetism and high spin polarization are intrinsic properties of this DMOS. Our results argue for the DMOS approach with complex oxide materials in spintronics.

Full oxide heterostructure combining a high-TCdiluted ferromagnet with a high-mobility conductor

“…In the present case, we know ρ N /ρ F ≈ 1 and β should be close to -1 as the spin-polarization of Co-LSTO is -80% 18 . In conventional metals, l sf is usually much longer than the mean free path λ.…”

“…2 shows that Co-LSTO films are ferromagnetic at room temperature, with a maximum saturation magnetization (M S ) of about 5 emu/cm 3 obtained for films grown at the lowest pressures (P O2 ≤ 5×10 experiments with, in particular, the analysis of the peculiar TMR bias dependence and the determination of the spin polarization (-80%) are presented elsewhere 18 .…”

Magnetism and metal-insulator transition in oxygen-deficientSrTiO3

“…This has been seen in interfacial structures 6,7 , but also in bulk and thin film , both in systems that are doped with other transition metals, but also those that are not. 1,[8][9][10][11] Recent advances in the synthesis of oxygendeficient structures have allowed for the detection, measurement and control of optically induced long-lived magnetic moments in STO, further implicating Ov 12 . Very recently is was shown than electrical gating at STO-based interfaces can be controlled to induce the appearance of magnetic moments dependent on the mobile carrier density 13 .…”

Systematic changes of the electronic structure of the diluted ferromagnetic oxide Li-dopedNi1−xFexOwith hole doping

“…Ever since the reports on theoretical material design for high T C DMS's [3,4], the discovery of room-temperature ferromagnetism in DMS's based on wide-band gap or oxide semiconductors has been reported [5,6] although the origin of the ferromagnetism has not been clarified yet. Meanwhile, various attempts of other approaches to higher T C have been made: These include nanostructure designing such as digital ferromagnetic heterostructures [7,8] and nanoparticles [9,10]; employment of new host materials such as, e.g., layered compound Sb 2 Te 3 [11], correlated metal (La,Sr)TiO 3 [12], and rare-earth oxide CeO 2 [13] instead of conventional semiconductors.…”