Tailoring Magnetic and Transport Anisotropies in Co100−x–Cux Thin Films through Obliquely Grown Nano-Sheets

The magnetic and transport properties of pulsed laser-deposited Co100−x–Cux thin films were tailored through their nano-morphology and composition by controlling for the deposition geometry, namely normal or oblique deposition, and their Cu content. All films were composed of an amorphous Co matrix and a textured growth of Cu nanocrystals, whose presence and size d increased as x increased. For x = 50, all films were superparamagnetic, regardless of deposition geometry. The normally deposited films showed no in-plane magnetic anisotropy. On the contrary, controllable in-plane uniaxial magnetic anisotropy in both direction and magnitude was generated in the obliquely deposited films. The magnetic anisotropy field Hk remained constant for x = 0, 5 and 10, Hk ≈ 35 kAm−1, and decreased to 28 and 26 kAm−1 for x = 20 and 30, respectively. This anisotropy had a magnetostatic origin due to a tilted nano-sheet morphology. In the normally deposited films, the coercive field Hc increased when x increased, from 200 (x = 0) to 1100 Am−1 (x = 30). In contrast, in obliquely deposited films, Hc decreased from 1500 (x = 0) to 100 Am−1 (x = 30) as x increased. Activation energy spectra corresponding to structural relaxation phenomena in obliquely deposited films were obtained from transport property measurements. They revealed two peaks, which also depended on their nano-morphology and composition.

Achieving broad absorption band and high incident angles by stochastically-distributed oblique-flat-sheet metamaterial perfect absorbers

In this work, we integrated a periodic seed layer and oblique deposition method to fabricate a stochastically-distributed oblique-flat-sheet metamaterial perfect absorber (MPA). Such design could increase its absorption bandwidth and tolerance to high angle-incidence due to the fact that various oblique flat sheets offer different resonance conditions while even a single oblique flat sheet could provide different optical paths for resonance. On the other hand, a seed layer could reduce uncertainty regarding to direct oblique deposition and provide abilities to manipulate the bandwidth of the MPA. We also setup a simulation model in the aids of Visual Basic Application and examined the absorption behavior of the MPA under TM and TE oblique incidence that could achieve high absorbance under 80° and 60° incidence, respectively. Finally, in measurement, the fabricated sample owns 65% absorbance within 80–250 THz and over 90% absorbance within 250–320 THz at x-polarization normal incidence; as for the y-polarization normal incidence, we could achieve overall 70% absorbance within 80–300 THz. The measured results reveal similar tendency compared to the simulated ones.

Oblique Deposition of Ti/Pt/Au Electrode on Photonic Crystal for Vertical Current Injection

We describe a device for inter-chip or intra-chip optical communications that contains the Circular Defect in photonic crystal (CirD) lasers array driven by vertical current injection. In order to improve the conductivity of the structure while also preventing current leakage, we introduce the oblique deposition of electrodes on a photonic crystal pattern by using an electron beam evaporation apparatus. The performance of an electrode is investigated by a transmission line method, and the CirD structure is fabricated with the electrode. We analyze the voltage-current relationship and confirm the CirD structure’s low resistance of under 1 kΩ.

Marked Enhancement of Roll-Off Frequency in FeCoN Synthetic Antiferromagnetic Films Deposited by Oblique Incidence

A series of FeCoN films were successfully deposited on glass substrates in a magnetron sputtering system. Using oblique incidence method and FeCoN/Ru/FeCoN synthetic antiferromagnetic (SAF) structure, two additional anisotropies energy were introduced: oblique incidence anisotropy and exchange anisotropy energy, which marked enhancement of the effective magnetic anisotropy (Hk). The increment of Hk results in a significant improvement in the roll-off frequency of these films. The roll-off frequency of FeCoN/Ru/FeCoN films with SAF structure can reach up to 8.6 GHz. A feasible approach to conveniently controlling Hk of soft magnetic thin films by using oblique deposition and SAF structure can further improve their properties for the potential applications in the high frequency region.