X-ray magnetic circular dichroism of ferromagnetic Co4N epitaxial films on SrTiO3(001) substrates grown by molecular beam epitaxy

5-nm thick Co4N layers capped with 3-nm thick Au layers were grown epitaxially on SrTiO3(001) substrates by molecular beam epitaxy using solid Co and a radio-frequency NH3 plasma. Spin and orbital magnetic moments of the Co4N layers were estimated using x-ray magnetic circular dichroism (XMCD) measurements at 300 K. The site-averaged Co 3d spin magnetic moment is evaluated to be about 1.4 μB, which is smaller than that predicted theoretically (1.58 μB). The element-specific XMCD intensities for the Co L3 edge and N K edge show that the magnetic moment is induced at the N atoms

Soft X-ray Absorption and Photoemission Studies of Ferromagnetic Mn-Implanted 3CC-SiC

We have performed x-ray photoemission spectroscopy (XPS), x-ray absorption spectroscopy (XAS), and resonant photoemission spectroscopy (RPES) measurements of Mn-implanted 3$C$-SiC (3$C$-SiC:Mn) and carbon-incorporated Mn$_{5}$Si$_{2}$ (Mn$_{5}$Si$_{2}$:C). The Mn 2$p$ core-level XPS and XAS spectra of 3$C$-SiC:Mn and Mn$_{5}$Si$_{2}$:C were similar to each other and showed "intermediate" behaviors between the localized and itinerant Mn 3$d$ states. The intensity at the Fermi level was found to be suppressed in 3$C$-SiC:Mn compared with Mn$_{5}$Si$_{2}$:C. These observations are consistent with the formation of Mn$_{5}$Si$_{2}$:C clusters in the 3$C$-SiC host, as observed in a recent transmission electron microscopy study.Comment: 4 pages, 3 figure

Mechanism of the performance improvement of TiO2-x-based field-effect transistor using SiO2 as gate insulator

RF magnetron sputtered titanium oxide (TiO2-x) thin films were used as active channel layer to fabricate field-effect transistors (FETs). In the as-prepared FETs, poor FET performance was found, with a low on-to-off current ratio of ∼500 and a high sub-threshold slope. It is attributed the existence of Si-O-Ti cross-linking bonding at TiO2-x/SiO2 interface, which was probed by X-ray Photoelectron Spectroscopy (XPS) measurement. A remark improvement of sub-threshold slope and on-to-off current ratio was observed due to post annealing in vacuum at 300 °C for 30min. By using the electron energy loss spectroscope (EELS) analysis, oxidization of TiO2-x layer closing to SiO2 layer region was found, suggesting that Si-O-Ti cross-linking bonding at TiO2-x/SiO2 interface breaks due to post annealing treatment

Reactive ion etching of transition-metal alloys

For production of advanced spin-electronic devices, such as a magnetic random access memory with the higher-density memory cell, a reactive ion etching (RIE) process of transition metal alloys is the indispensable component of development, while no transition-metal compounds with the relatively high vapor pressure have been founded so far. Here, we show the RIE process of a NiFe thin film by using CH4:O2:NH3 discharge. The RIE process was designed by ab initio calculations, and the present result is the first successful demonstration of the chemical effect in the RIE process for transition-metal alloys. The relative etching ratio of NiFe against Ti as the metal mask was decreased by substituting CH4 with CHF3

First principles based investigations of materials for resistive RAM

We investigate the suitable materials and device structures for Resistive Random Access Memory (ReRAM) based on the first principles calculations. Our calculations base on the model in which the transition metal oxide layers consist of three atomic layers. From the results of energy gap and magnetic moment of the transition metals, we can expect that CoO/NiO/CoO for the transition metal oxide layer exhibits high-resistance change and high-speed response. Copyright © 2008 American Scientific Publishers. All rights reserved