Growth morphology, structure, and magnetism of ultrathin Co films on W(111)

Abstract

The growth morphology, structure, and magnetism of ultrathin Co films on the W͑111͒ surface are studied with conventional and spin polarized low energy electron microscopy and diffraction and first principles total energy calculations. Pseudo-layer-by-layer growth of thick pseudomorphic ͑ps͒ Co films is observed at 380 K, while Stranski-Krastanov growth and transformation to a ͑6ϫ6͒ closed-packed structure are observed at higher temperatures. On the basis of the calculations, only one ps Co monolayer is expected to be thermodynamically stable against three-dimensional island formation. Calculations also indicate that the magnetic moment on Co atoms at the interface is reduced due to strong hybridization with the substrate, but remains non-zero even for the single ps monolayer. Metastable ps Co/W͑111͒ is found experimentally to be ferromagnetically ordered at 380 K when film thickness exceeds 7.6 ps ML. Although only in-plane magnetization is observed, substrate atomic steps have a strong influence on the magnetization easy axis and magnetic domain structure, which suggests that the in-plane magnetocrystalline anisotropy is weak.

Hydrogen adsorption promoted perpendicular magnetic anisotropy in nano-structured Fe coverage on Pd/W{112} faceting surface

“…Besides, tungsten-based devices have been extensively studied and applied in spin detector and single atom tip, due to the high thermal stability of tungsten. 9 [13][14][15] However the preparation of a magnetic nano-pyramid on the tip point is still challenging, and the study of the related magnetic properties is lacking. This leads us to the investigation of magnetic coverage on the Pd/W{112} faceting surface.…”

Full field electron spectromicroscopy applied to ferroelectric materials

“…75,76 Spin polarized LEEM can probe both in and out of plane magnetization by means of the spin dependent exchange scattering. 77 A final direction of research which will benefit from PEEM and LEEM techniques is the behavior and the characterization of structures on device scales. Using suitable, customized sample holders, it is possible to wire up for example a single microscopic capacitor and, using the high spatial resolution study its response to current or voltage.…”

Oxygen surfactant-assisted growth and dewetting of Co films on O-3 × 3/W(111)

“…In 2003, Man et al reported the growth morphology, structure, and magnetism of Co films on clean W(111) surface by spinpolarized low energy electron microscope (SP-LEEM) and LEED. 19 Pseudo-layer-by-layer growth of Co films was observed at 380 K, while Stranski-Krastanov growth was observed at higher temperature. However, based on their calculation but contradicting the conclusion of Guan et al, only one pseudomorphic layer (¼1/3 PML) was predicted to be thermodynamically stable against 3D island formation.…”

“…17,18 Despite the above promising applications, there are only a few studies reporting magnetic transition metals on the W(111) surface. 10,[19][20][21] In 1996, the structure and morphology of Co films on a clean W(111) surface were reported by Guan et al using low energy electron spectroscopy (LEED) and Auger electron spectroscopy (AES). Pseudomorphic Co films were grown at room temperature (RT) with thickness up to 4 PML.…”