The number of two-dimensional (2D) materials has grown steadily since the discovery of graphene. Each new 2D material demonstrated unusual physical properties offering a large flexibility in their tailoring for high-tech applications. Here, we report on the formation and characterization of an uncharted 2D material: ‘Cu2Te alloy monolayer on Cu(111) surface’. We have successfully grown a 2D binary Te-Cu alloy using a straightforward approach based on chemical deposition method. Low electron energy diffraction (LEED) and scanning tunneling microscopy (STM) results reveal the existence of a well-ordered alloy monolayer characterized by (√3 × √3)R30° superstructure, while the x-ray photoemission spectroscopy (XPS) measurements indicate the presence of single chemical environment of the Te atoms associated with the Te-Cu bonding. Analysis of the valence band properties by angle resolved photoemission spectroscopy (ARPES); in particular the electronic states close to the Fermi level suggests a strong hybridization between Te and Cu electronic states leading to an appearance of new dispersive bands localized at the surface alloy, which is confirmed by first-principles calculations. These bands are strongly influenced by the surface reconstruction and undergo a back-folding at the boundaries of the reduced surface Brillouin zone (SBZ). More interesting, a band gap of about 0.91 eV and a Rashba splitting in the conduction band are obtained. These findings taken together clearly prove the presence of 2D-type electron system within the Cu2Te alloy layer, which is promising for spintronic application.
Magnetic material is the key component in lot of electromagnetically-based optical to microwave applications. In the case of radio-frequencies/microwave applications, passive components are developed using planar design to facilitate their fabrication while 3D geometries are the best shapes to improve components properties. But nowadays, 3D printing technologies are coming up in industries and 3D design of passive components grows in interest. But 3D shaping of magnetic material remains a problem which has to be solved before considering industrial implementation.In this work, we demonstrate the possibility of 3D shaping ferrite magnetic powder using Selective laser melting/sintering in ambient air. A ferrimagnetic powder of Yttrium Iron Garnet (YIG) was used to form a 10-layers stack of magnetic material. A simple method for small surface (10x10mm²) deposition of powder was developed by dispersing the YIG powder into ethanol. A drop is then deposited on top of a substrate. Ethanol evaporates and an homogeneous layer is obtained. A 1064nm-nanosecond laser combined to a scanning lens is used to irradiate the powder layer and induce melting/sintering of the powder at ambient temperature and in ambient air. Chemical and structural changes induced by the laser process were studied using Raman spectroscopy. Results show that a part of the YIG was decomposed into a weakly magnetic phase of Fe3O4. Vibrating Sample Magnetometry was then used to compare the magnetic behavior of the YIG multilayer and the YIG powder. The multilayer always exhibit a magnetic behavior whatever the substrate is: YIG powder, YIG bulk or Al bulk.
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