Dilute magnetic semiconductor and half metal behaviors in 3d transition-metal doped black and blue phosphorenes: a first-principles study

We present first-principles density-functional calculations for the structural, electronic, and magnetic properties of substitutional 3d transition metal (TM) impurities in two-dimensional black and blue phosphorenes. We find that the magnetic properties of such substitutional impurities can be understood in terms of a simple model based on the Hund's rule. The TM-doped black phosphorenes with Ti, V, Cr, Mn, Fe and Ni impurities show dilute magnetic semiconductor (DMS) properties while those with Sc and Co impurities show nonmagnetic properties. On the other hand, the TM-doped blue phosphorenes with V, Cr, Mn and Fe impurities show DMS properties, those with Ti and Ni impurities show half-metal properties, whereas Sc and Co doped systems show nonmagnetic properties. We identify two different regimes depending on the occupation of the hybridized electronic states of TM and phosphorous atoms: (i) bonding states are completely empty or filled for Sc- and Co-doped black and blue phosphorenes, leading to non-magnetic; (ii) non-bonding d states are partially occupied for Ti-, V-, Cr-, Mn-, Fe- and Ni-doped black and blue phosphorenes, giving rise to large and localized spin moments. These results provide a new route for the potential applications of dilute magnetic semiconductor and half-metal in spintronic devices by employing black and blue phosphorenes.Comment: 9 pages, 7 figure

The Safety and Efficacy of Transconjunctival Sutureless 23-gauge Vitrectomy

PURPOSE: To evaluate the efficacy and safety of vitreoretinal surgery using a 23-gauge transconjunctival sutureless vitrectomy (TSV) system for various vitreoretinal diseases. METHODS: A retrospective, consecutive, interventional case series was performed for 40 eyes of 40 patients. The patients underwent vitreoretinal procedures using the 23-gauge TSV system, including idiopathic epiretinal membrane (n=7), vitreous hemorrhage (n=11), diabetic macular edema (n=10), macular hole (n=5), vitreomacular traction syndrome (n=5), diabetic tractional retinal detachment (n=1), and rhegmatogenous retinal detachment (n=1). Best corrected visual acuity (BCVA), intraocular pressure (IOP), and intra- and post-operative complications were evaluated. RESULTS: Intraoperative suture placement was necessary in 3 eyes (7.5%). The median BCVA improved from 20/400 (LogMAR, 1.21+/-0.63) to 20/140 (LogMAR, 0.83+/-0.48) at 1 week (p=0.003), 20/100 (LogMAR, 0.85+/-0.65) at 1 month (p=0.002), 20/100 (LogMAR, 0.73+/-0.6) at 3 months (p=0.001). In 1 eye, IOP was 5 mmHg at 2 hours and 4 mmHg at 5 hours, but none of the eyes showed hypotony after 1 postoperative day. No serous postoperative complications were observed during a mean follow-up of 8.4+/-3.4 months (range 3-13 months) CONCLUSIONS: The 23-gauge TSV system shows promise as an effective and safe technique for a variety of vitreoretinal procedures. It appears to be a less traumatic, more convenient alternative to 20-gauge vitrectomy in some indications

A 'reality of return': the case of the Sarawakian-Chinese visiting China

Using an interpretive ethnographic framework, this paper focuses on how travel to the homeland informs the identity of the Sarawakian-Chinese, a diaspora that contains a composite of subcultures. The data collection is based upon 35 semi-structured interviews and participant observation of a Sarawakian-Chinese tour group to China. Whilst emotional connections with China are universally significant in constructing the diaspora's ethnic identity, the strength of association is influenced by characteristics of education, religion and language, as identity becomes re-defined and plural. The findings suggest that the influence of tourism to the homeland may not necessarily be significant in enhancing emotional and cultural connections with China. Instead, ambivalent connections to homeland become established during tourism experiences. Visits to the homeland could play a significant role in forging new and hybrid identities of ethnic communities outside the homeland, thereby bringing a new vital dimension to identity formation and communication of the Sarawakian-Chinese in the future

Electron transport properties in magnetic tunnel junctions with epitaxial NiFe (111) ferromagnetic bottom electrodes

科研費報告書収録論文(課題番号:13305001・基盤研究(A)(2) ・H13～H15/研究代表者:宮崎, 照宣/高品位微小トンネル接合へのスピン注入

Charge density wave and superconductivity in the kagome metal CsV3_3Sb5_5 around a pressure-induced quantum critical point

Using first-principles density functional theory calculations, we investigate the pressure-induced quantum phase transition (QPT) from the charge density wave (CDW) to the pristine phase in the layered kagome metal CsV$_3$Sb$_5$ consisting of three-atom-thick Sb$-$V$_3$Sb$-$Sb and one-atom-thick Cs layers. The CDW structure having the formation of trimeric and hexameric V atoms with buckled Sb honeycomb layers features an increase in the lattice parameter along the $c$ axis, compared to its counterpart pristine structure having the ideal V$_3$Sb kagome and planar Sb honeycomb layers. Consequently, as pressure increases, the relatively smaller volume of the pristine phase contributes to reducing the enthalpy difference between the CDW and pristine phases, yielding a pressure-induced QPT at a critical pressure $P_c$ of ${\sim}$2 GPa. Furthermore, we find that (i) the superconducting transition temperature $T_c$ increases around $P_c$ due to a phonon softening associated with the periodic lattice distortion of V trimers and hexamers and that (ii) above $P_c$, optical phonon modes are hardened with increasing pressure, leading to monotonous decreases in the electron-phonon coupling constant and $T_c$. Our findings not only demonstrate that the uniaxial strain along the $c$ axis plays an important role in the QPT observed in CsV$_3$Sb$_5$, but also provide an explanation for the observed superconductivity around $P_c$ in terms of a phonon-mediated superconducting mechanism

A Narrow Linewidth Singly Resonant ZGP OPO for Multiple Lidar Applications

A singly resonant, injection seeded Zinc Germanium Phosphide (ZGP) optical parametric oscillator (OPO), capable to tune over 4.3-10.1 microns, is demonstrated. This ZGP OPO uses a bow-tie cavity with a partially reflective mirror for injection seeding at the signal wavelength. The injection seed source can be either a continuous wave 3.39 m laser or a tunable near-infrared OPO laser, which provides wide wavelength tuning capability. The injection seeded ZGP OPO narrows the idler wavelength linewidth to less than 1nm, limited by the measurement resolution of the monochromator. This device has potential to be used as a transmitter for multiple purpose lidar applications