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The ability to control the spin textures in semiconductors is a fundamental step toward novel spintronic devices, while seeking desirable materials exhibiting persistent spin texture (PST) remains a key challenge. The PST is the property of materials preserving a unidirectional spin orientation in the momentum space, which has been predicted to support an extraordinarily long spin lifetime of carriers. Herein, by using first-principles density functional theory calculations, we report the emergence of the PST in the two-dimensional (2D) germanium monochalcogenides (GeMC). By considering two stable formation of the 2D GeMC, namely the pure GeX and Janus Ge 2 XY monolayers (X, Y = S, Se, and Te), we observed the PST around the valence band maximum where the spin orientation is enforced by the lower point group symmetry of the crystal. In the case of the pure GeX monolayers, we found that the PST is characterized by fully out-of-plane spin orientation protected by C 2v point group, while the canted PST in the y-z plane is observed in the case of the Janus Ge 2 XY monolayers due to the lowering symmetry into C s point group. More importantly, we find large spin-orbit coupling (SOC) parameters in which the PST sustains, which could be effectively tuned by in-plane strain. The large SOC parameter observed in the present systems leads to the small wavelength of the spatially periodic mode of the spin polarization, which is promising for realization of the short spin channel in the spin Hall transistor devices.

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Hydroxyapatite (Ca10(PO4)6(OH2), HA has similarities with human bone mineral composition and morphology, bioactive, and non-toxic. However, HA has a weakness in the decay of material, so it can inhibit the growth of new bone tissue. The other materials used as biodegradable bone substitute are Tri Calcium Phosphate (TCP). It has the reception of the body is almost as good as HA but it have fast decay time, so that the material has been discharged before the newly formed tissue. This study aimed to developed a Biphasic Calcium Phosphate (BCP) which is a combination of the properties of HA and TCP, it makes the decay time can be in accordance with the growth of new bone tissue. Calcination method was used in this study. Four groups of bovine bone samples were calcined at four different temperatures ranging from 1000oC to 1300oC using the electric furnace. The heating rate during calcination process was 5oC/minute and dwell time of 2 hours. The calcined bioceramics samples are being examined to determine the characterization of materials. XRD testing to determine the chemical compounds, FTIR performed to determine the ionic bonds that exist in materials and SEM to determine the microstructure of the material calcination results. The current investigation confirms the possibility of producing porous BCP bone graft from porous bovine bone cube, without any important impurities as indicated by XRD and FT-IR techniques. The partially decomposition of HA into TCP was started when bovine bone samples were heated at 1200oC.