arXiv subjects

Chris Leighton

Publications and source records attributed to Chris Leighton.

21 records · Page 2Linked to original sources

arXiv2016

Theory of Kondo suppression of spin polarization in nonlocal spin valves

We theoretically analyze contributions from the Kondo effect to the spin polarization and spin diffusion length in all-metal nonlocal spin valves. Interdiffusion of ferromagnetic atoms into the normal metal layer creates a region in which Kondo physics plays a significant role, giving discrepancies between experiment and existing theory. We start from a simple model and construct a modified spin drift-diffusion equation which clearly demonstrates how the Kondo physics not only suppresses the electrical conductivity but even more strongly reduces the spin diffusion length. We also present an explicit expression for the suppression of spin polarization due to Kondo physics in an illustrative regime. We compare this theory to previous experimental data to extract an estimate of the Elliot-Yafet probability for Kondo spin flip scattering of 0.7 $\pm$ 0.4, in good agreement with the value of 2/3 derived in the original theory of Kondo.

cond-mat.mes-hall↗

arXiv2016

Electronic structure of BaSnO3 investigated by high-energy-resolution electron energy-loss spectroscopy and ab initio calculations

There has been growing interest in perovskite BaSnO3 due to its desirable properties for oxide electronic devices including high electron mobility at room temperature and optical transparency. As these electronic and optical properties originate largely from the electronic structure of the material, here the basic electronic structure of epitaxially-grown BaSnO3 films is studied using high-energy-resolution electron energy-loss spectroscopy in a transmission electron microscope and ab initio calculations. This study provides a detailed description of the dielectric function of BaSnO3, including the energies of bulk plasmon excitations and critical interband electronic transitions, the band structure and partial densities of states, the measured band gap, and more. To make the study representative of a variety of deposition methods, results from BaSnO3 films grown by both hybrid molecular beam epitaxy and high pressure oxygen sputter deposition are reported.

cond-mat.mtrl-sci↗

arXiv2012

Surface Roughness Dominated Pinning Mechanism of Magnetic Vortices in Soft Ferromagnetic Films

Although pinning of domain walls in ferromagnets is ubiquitous, the absence of an appropriate characterization tool has limited the ability to correlate the physical and magnetic microstructures of ferromagnetic films with specific pinning mechanisms. Here, we show that the pinning of a magnetic vortex, the simplest possible domain structure in soft ferromagnets, is strongly correlated with surface roughness, and we make a quantitative comparison of the pinning energy and spatial range in films of various thickness. The results demonstrate that thickness fluctuations on the lateral length scale of the vortex core diameter, i.e. an effective roughness at a specific length scale, provides the dominant pinning mechanism. We argue that this mechanism will be important in virtually any soft ferromagnetic film.

cond-mat.mtrl-sci↗