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The growth and magnetic properties of epitaxial magnetite Fe3O4 on Si(100) using MgO buffer layer have been studied by reflection high-energy electron diffraction, X-ray photoelectron spectroscopy, and magneto-optical Kerr effect. The epitaxial Fe3O4 films were prepared by in situ post growth annealing of ultrathin epitaxial Fe films at 220 °C in an oxygen partial pressure of 8 × 10-4 mbar. The epitaxial relationship was found to be Fe3O4(100)(001)//MgO(100)(001)//Si(100)(001) with the MgO film grown cube-on-cube orientation with the Si substrate. While the Fe unit cell rotates 450 to match that of the MgO buffer layer, it rotates 45° back upon oxidation. A low saturation field has been observed indicating low density of antiphase boundaries. [ABSTRACT FROM AUTHOR]

In this paper, the authors report on the investigation on the effect of inserting an epitaxial MgO layer on the structural and magnetic properties of Fe[sub3]O[sub4] ultrathin films grown on GaAs(100) by combined techniques of molecular beam epitaxy and postgrowth annealing in an oxygen atmosphere. The MgO films were grown with a cube-on-cube orientation to GaAs. The epitaxial Fe[sub3]O[sub4] lattice cell was rotated by 45° in respect to that of MgO and GaAs due to the lattice relaxation of the magnetic layer. All samples studied exhibited strong fourfold cubic magnetic anisotropy with easy axes along the (001) directions of GaAs. A dramatic decrease in the uniaxial anisotropy constant in the presence of the MgO barrier was observed. The existence of the uniaxial magnetic anisotropy in the Fe[sub3]O[sub4]/GaAs hybrid structure has been attributed to the interfacial contact between the magnetite film and the GaAs. [ABSTRACT FROM AUTHOR]

We report the evolution of Fe oxide nanostructures on GaAs(100) upon pre- and post-growth annealing conditions. GaAs nanoscale pyramids were formed on the GaAs surface due to wet etching and thermal annealing. An 8.0-nm epitaxial Fe film was grown, oxidized, and annealed using a gradient temperature method. During the process the nanostripes were formed, and the evolution has been demonstrated using transmission and reflection high energy electron diffraction, and scanning electron microscopy. These nanostripes exhibited uniaxial magnetic anisotropy. The formation of these nanostructures is attributed to surface anisotropy, which in addition could explain the observed uniaxial magnetic anisotropy. [ABSTRACT FROM AUTHOR]

Ultrathin Fe oxide films of various thicknesses prepared by post-growth oxidation on GaAs(100) surface have been investigated with X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD). The XPS confirms that the surfaces of the oxide are Fe3 O4 rather than Fe2O3. XAS and XMCD measurements indicate the presence of insulating Fe divalent oxide phases (FeO) beneath the surface Fe3 O4 layer with the sample thickness above 4 nm. This FeO might act as a barrier for the spin injection into the GaAs. [ABSTRACT FROM AUTHOR]

Thin film multilayer materials are very important for a variety of key technologies such as hard drive storage. However, their multilayered nature means it can be difficult to examine them after production and determining properties of individual layers is harder still. Here, methods of preparing multilayer samples for examination using scanning thermal microscopy are compared, showing that both a combination of mechanical and ion beam polishing, and ion beam milling to form a crater produce suitable surfaces for scanning thermal microscopy examination. However, the larger exposed surfaces of the ion beam milled crater are the most promising for distinguishing between the layers and comparison of their thermal transport properties., (Creative Commons Attribution license.)

Molybdenum disulfide (MoS 2 ) nanosheets exhibit anisotropic optical and electronic properties, stemming from their shape and electronic structure. Unveiling this anisotropy for study and usage in materials and devices requires the ability to control the orientation of dispersed nanosheets, but to date this has proved a challenging proposition. Here, we demonstrate magnetic field driven alignment of MoS 2 nanosheets in a liquid crystal (LC) polymer and unveil the optical properties of the resulting anisotropic assembly. Nanosheet optical anisotropy is observed spectroscopically by Raman and direction-dependent photoluminescence (PL) measurements. Resulting data indicate significantly lower PL emission due to optical excitation with electric field oscillation out of plane, parallel to the MoS 2 c -axis, than that associated with perpendicular excitation, with the dichroic ratio I perp / I par = 3. The approach developed here provides a useful route to elucidate anisotropic optical properties of MoS 2 nanosheets and to utilize such properties in new materials and devices.

Purpose The incidence of contralateral prophylactic mastectomy (CPM) has continued to increase. We prospectively examined psychosocial outcomes before and up to 18 months after surgery in women who did or did not have CPM. Methods Women with unilateral, nonhereditary breast cancer completed questionnaires before and 1, 6, 12, and 18 months after surgery. Primary psychosocial measures were cancer worry and cancer-specific distress. Secondary measures were body image, quality of life (QOL), decisional satisfaction, and decisional regret. Results A total of 288 women (mean age, 56 years; 58% non-Hispanic white) provided questionnaire data, of whom 50 underwent CPM. Before surgery, women who subsequently received CPM had higher cancer distress ( P = .04), cancer worry ( P < .001), and body image concerns ( P < .001) than women who did not have CPM. In a multivariable repeated measures model adjusted for time, age, race/ethnicity, and stage, CPM was associated with more body image distress ( P < .001) and poorer QOL ( P = .02). There was a significant interaction between time point and CPM group for cancer worry ( P interaction < .001), suggesting that CPM patients had higher presurgery cancer worry, but their postsurgery worry decreased over time and was similar to the worry of patients who did not have CPM. QOL was similar between CPM groups before surgery but declined 1 month after surgery and remained lower than patients who did not have CPM after surgery ( P interaction = .05). Conclusion These results may facilitate informed discussions between women and their physicians regarding CPM. Fear and worry may be foremost concerns at the time surgical decisions are made, when women may not anticipate the adverse future effect of CPM on body image and QOL.