First-principles study of the spin-mixing conductance in Pt/Ni81_{81}Fe19_{19} junctions

Based on the spin-pumping theory and first-principles calculations, the spin-mixing conductance (SMC) is theoretically studied for Pt/Permalloy (Ni$_{81}$Fe$_{19}$, Py) junctions. We evaluate the SMC for ideally clean Pt/Py junctions and examine the effects of interface randomness. We find that the SMC is generally enhanced in the presence of interface roughness as compared to the ideally clean junctions. Our estimated SMC is in good quantitative agreement with the recent experiment for Pt/Py junctions. We propose possible routes to increase the SMC in Pt/Py junctions by depositing a foreign magnetic metal layer in Pt, offering guidelines for designing the future spintronic devices.Comment: Accepted for publication in Applied Physics Letter

Towards precise measurement of oscillatory domain wall by ferromagnetic Josephson junction

We theoretically propose a principle for precise measurement of oscillatory domain wall (DW) by a ferromagnetic Josephson junction, which is composed of a ferromagnetic wire with DW and two superconducting electrodes. The current-voltage curve exhibits stepwise structures, only when DW oscillates in the ferromagnetic wire. The voltage step appears at V = n(\hbar/2e)\omega_DW with the fundamental constant \hbar/e, integer number n, and the DW frequency \omega_DW. Since V can be determined in the order of 10^9 accuracy, the oscillatory DW will be measured more precisely than present status by conventional method.Comment: 3 pages, 2 figure

Optical properties of N+ ion-implanted and rapid thermally annealed Si(100) wafers studied by spectroscopic ellipsometry

The optical properties of N+ ion-implanted Si(100) wafers have been studied using the spectroscopic ellipsometry (SE). The N+ ions are implanted at 150 keV with fluences in the range between 1 ×10↑16 and 7.5×10↑16 cm−2 at room temperature. A Bruggeman effective-medium-approximation and a linear-regression analysis require a four-phase model (substrate/first and second damaged layers/ambient) to explain the experimental data of the as-implanted samples. These analyses suggest that the buried fully amorphous layer can be formed at around ～5×10↑16 cm−2 dose. The rapid thermal annealing is performed at 750°C in a dry N2 atmosphere on N+ ion-implanted samples. The SE data reveal that the recrystallization starts to occur very quickly. The time constant for the defect annealing in the deeper damaged layer is determined to be 36 s. The dielectric-function spectra ε(E) of microcrystalline silicon deduced here differ appreciably from that of the single-crystalline silicon, especially in the vicinity of the critical points