Spin transport properties in a naphthyl diamine derivative film investigated by the spin pumping

We report the spin transport properties in a thin film of a naphthyl diamine derivative: N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine (alpha-NPD). In a palladium(Pd)/alpha-NPD/Ni80Fe20 tri-layer structure sample, a pure spin current is generated in the alpha-NPD layer with the spin pumping driven by ferromagnetic resonance (FMR). The generated spin current is absorbed into the Pd layer, and converted into a charge current with the inverse spin-Hall effect (ISHE) in Pd. An electromotive force due to the ISHE in the Pd layer is observed under the FMR of the Ni80Fe20 layer, which is clear evidence for the spin transport in an alpha-NPD film. The spin diffusion length in an alpha-NPD film is estimated to be about 62 nm at room temperature, which is long enough as a spin transport material for spintronic devices.Comment: 21 pages, 5 figures. To be appeared in Solid State Commu

Solvent effects on charge transfer bands of nitrogen-centered intervalence compounds

Electron transfer parameters are extracted from the optical spectra of intervalence bis(hydrazine) radical cations. Compounds with 2-tert-butyl-3-phenyl-2,3-diazabicyclo[2.2.2]octyl-containing charge-bearing units that are doubly linked by 4-σ-bond and by 6-σ-bond saturated bridges are compared with ones having tert-butylisopropyl- and diphenyl-substituted charge bearing units and others having the aromatic units functioning as the bridge. Solvent effect studies show that the optical transition energy (E_(op)) does not behave as dielectric continuum theory predicts but that solvent reorganization energy may be usefully separated from the vibrational reorganization energy by including linear terms in both the Pekar factor (γ) and the Gutmann donor number (DN) in correlating the solvent effect. Solvation of the bridge for these compounds is too large to ignore, which makes dielectric continuum theory fail to properly predict solvent effects on either E_(op) or the free energy for comproportionation

Real-time nanodiamond thermometry probing in vivo thermogenic responses

蛍光ナノダイヤモンドを用いた量子温度計により動物個体の発熱を捉えることに成功. 京都大学プレスリリース. 2020-09-25.Get diamonds, take temperature. 京都大学プレスリリース. 2020-10-06.Real-time temperature monitoring inside living organisms provides a direct measure of their biological activities. However, it is challenging to reduce the size of biocompatible thermometers down to submicrometers, despite their potential applications for the thermal imaging of subtissue structures with single-cell resolution. Here, using quantum nanothermometers based on optically accessible electron spins in nanodiamonds, we demonstrate in vivo real-time temperature monitoring inside Caenorhabditis elegans worms. We developed a microscope system that integrates a quick-docking sample chamber, particle tracking, and an error correction filter for temperature monitoring of mobile nanodiamonds inside live adult worms with a precision of ±0.22°C. With this system, we determined temperature increases based on the worms’ thermogenic responses during the chemical stimuli of mitochondrial uncouplers. Our technique demonstrates the submicrometer localization of temperature information in living animals and direct identification of their pharmacological thermogenesis, which may allow for quantification of their biological activities based on temperature

Self-induced inverse spin-Hall effect in an iron and a cobalt single-layer films themselves under the ferromagnetic resonance

The inverse spin-Hall effect (ISHE) is produced even in a “single-layer” ferromagnetic material film. Previously, the self-induced ISHE in a Ni80Fe20 film under the ferromagnetic resonance (FMR) was discovered. In this study, we observed an electromotive force (EMF) in an iron (Fe) and a cobalt (Co) single-layer films themselves under the FMR. As origins of the EMFs in the films themselves, the ISHE was main for Fe and dominant for Co, respectively 2 and 18 times larger than the anomalous Hall effect. Thus, we demonstrated the self-induced ISHE in an Fe and a Co single-layer films themselves under the FMR