ABSTRACT
All-oxide-based synthetic antiferromagnets (SAFs) are attracting intense research interest due to their superior tunability and great potentials for antiferromagnetic spintronic devices. In this work, using the La2/3Ca1/3MnO3/CaRu1/2Ti1/2O3 (LCMO/CRTO) superlattice as a model SAF, we investigated the layer-resolved magnetic reversal mechanism by polarized neutron reflectivity. We found that the reversal of LCMO layer moments is mediated by nucleation, expansion, and shrinkage of a magnetic soliton. This unique magnetic reversal process creates a reversed magnetic configuration of the SAF after a simple field cycling. Therefore, it can enable vertical data transfer from the bottom to the top of the superlattice. The physical origin of this intriguing magnetic reversal process could be attributed to the cooperation of the surface spin-flop effect and enhanced uniaxial magnetic anisotropy of the bottom LCMO layer. This work may pave a way to utilize all-oxide-based SAFs for three-dimensional spintronic devices with vertical data transfer and high-density data storage.
ABSTRACT
Manganites have shown potential in spintronics because they exhibit high spin polarization. Here, by ferromagnetic resonance we have studied the damping properties of La0.67Sr0.33MnO3/Pt bilayers which are prepared by oxide molecular beam epitaxy. The damping coefficient (α) of a La0.67Sr0.33MnO3 (LSMO) single layer is found to be 0.0104. However the LSMO/Pt bilayers exhibit a decrease in α with an increase in Pt thickness. This decrease in the value of α is probably due to high anti-damping like torque. Furthermore, we have investigated the angle dependent inverse spin Hall effect (ISHE) to quantify the spin pumping voltage from other spin rectification effects such as the anomalous Hall effect and anisotropic magnetoresistance. We have observed a high spin pumping voltage (â¼20 µV). The results indicate that both anti-damping and spin pumping phenomena occur simultaneously.
ABSTRACT
To shed light on the role of magnetism on the superconducting mechanism of the oxygen-free FeAs pnictides, we investigate the effect of magnetic ordering on phonon dynamics in the low-temperature orthorhombic parent compounds, which present a spin density wave. The study covers both the 122 (AFe(2)As(2); A = Ca, Sr, Ba) and 1111 (AFeAsF; A = Ca, Sr) phases. We extend our recent work on the Ca (122 and 1111) and Ba (122) cases by treating, computationally and experimentally, the 122 and 1111 Sr compounds. The effect of magnetic ordering is investigated through detailed non-magnetic and magnetic lattice dynamical calculations. The comparison of the experimental and calculated phonon spectra shows that the magnetic interactions/ordering have to be included in order to reproduce well the measured density of states. This highlights a spin-correlated phonon behavior which is more pronounced than the apparently weak electron-phonon coupling estimated in these materials. Furthermore, there is no noticeable difference between phonon spectra of the 122 Ba and Sr, whereas there are substantial differences when comparing these to CaFe(2)As(2) originating from different aspects of structure and bonding.
