According to density functional theory （DFT） using the plane wave base and pseudo-potential, we investigate the effects of the specific location of oxygen vacancy （Vo） in a （Ti,Co）06 distorted octahedron on the ...According to density functional theory （DFT） using the plane wave base and pseudo-potential, we investigate the effects of the specific location of oxygen vacancy （Vo） in a （Ti,Co）06 distorted octahedron on the spin density and magnetic properties of Co-doped rutile Ti02 dilute magnetic semiconductors. Our calculations suggest that the Vo location has a significant influence on the magnetic moment of individual Co cations. In the case where two Co atoms are separated far away from each other, when the Vo is located at the equatorial site of a Co-contained octahedron, the ground state of the two Co cations is d6（t3g↑, t23g ↓） without any magnetic moment. However, if the Vo is located at the apical site, these two Co sites have different ground states and magnetic moments. The spin densities are also observed to be modified by the exchange coupling between the Co cations and the location of Vo. Some positive spin polarization is induced around the adjacent O ions.展开更多
Present paper describes the investigation of vacancy (V) and interstitial (I) annihilation on oxygen atoms by means of infrared (IR) absorption and Hall-effect measurements of the accumulation of vacancy-oxygen comple...Present paper describes the investigation of vacancy (V) and interstitial (I) annihilation on oxygen atoms by means of infrared (IR) absorption and Hall-effect measurements of the accumulation of vacancy-oxygen complexes (VO) in Si crystals at high energy electron irradiation. Silicon samples, containing along with isolated oxygen atoms, more complicated oxygen quasi-molecules of SiOn (n = 1, 2, 3…) type, were used. At isochronal and isothermal annealing in the temperature range of 300°C - 350°C, apart from the reaction of vacancy capturing by oxygen atoms with formation of A-centers, more complicated reactions with participation of vacancies and oxygen atoms were observed: A-centers, oxygen containing quasi-molecules. A model is suggested to describe the observed processes that are qualitatively different from those taking place in samples containing completely dissociated oxygen.展开更多
The nitrogen vacancy(NV)center in diamond has been well applied in quantum sensing of electromagnetic field and temperature,where the sensitivity can be enhanced by the number of NV centers.Here,we used electron beam ...The nitrogen vacancy(NV)center in diamond has been well applied in quantum sensing of electromagnetic field and temperature,where the sensitivity can be enhanced by the number of NV centers.Here,we used electron beam irradiation to increase the generation rate of NV centers by nearly 22 times.We systematically studied the optical and electronic properties of the NV center as a function of an electron irradiation dose,where the detection sensitivity of magnetic fields was improved.With such samples with dense NV centers,a sub-pico-Tesla sensitivity in magnetic fields detection can be achieved with optimal controls and detections.展开更多
基金supported by the National Basic Research Program of China (Grant Nos. 2009CB929201, 2010CB934202, and2011CB921801) the National Natural Sciences Foundation of China (Grant Nos. 50931006, 50721001, and 11034004)
文摘According to density functional theory （DFT） using the plane wave base and pseudo-potential, we investigate the effects of the specific location of oxygen vacancy （Vo） in a （Ti,Co）06 distorted octahedron on the spin density and magnetic properties of Co-doped rutile Ti02 dilute magnetic semiconductors. Our calculations suggest that the Vo location has a significant influence on the magnetic moment of individual Co cations. In the case where two Co atoms are separated far away from each other, when the Vo is located at the equatorial site of a Co-contained octahedron, the ground state of the two Co cations is d6（t3g↑, t23g ↓） without any magnetic moment. However, if the Vo is located at the apical site, these two Co sites have different ground states and magnetic moments. The spin densities are also observed to be modified by the exchange coupling between the Co cations and the location of Vo. Some positive spin polarization is induced around the adjacent O ions.
文摘Present paper describes the investigation of vacancy (V) and interstitial (I) annihilation on oxygen atoms by means of infrared (IR) absorption and Hall-effect measurements of the accumulation of vacancy-oxygen complexes (VO) in Si crystals at high energy electron irradiation. Silicon samples, containing along with isolated oxygen atoms, more complicated oxygen quasi-molecules of SiOn (n = 1, 2, 3…) type, were used. At isochronal and isothermal annealing in the temperature range of 300°C - 350°C, apart from the reaction of vacancy capturing by oxygen atoms with formation of A-centers, more complicated reactions with participation of vacancies and oxygen atoms were observed: A-centers, oxygen containing quasi-molecules. A model is suggested to describe the observed processes that are qualitatively different from those taking place in samples containing completely dissociated oxygen.
基金supported by the National Key Research and Development Program of China(No.2017YFA0304504)the National Natural Science Foundation of China(Nos.91536219 and 91850102)+2 种基金the Anhui Initiative in Quantum Information Technologies(No.AHY130000)the Science Challenge Project(No.TZ2018003)the Fundamental Research Funds for the Central Universities(No.WK2030000020)。
文摘The nitrogen vacancy(NV)center in diamond has been well applied in quantum sensing of electromagnetic field and temperature,where the sensitivity can be enhanced by the number of NV centers.Here,we used electron beam irradiation to increase the generation rate of NV centers by nearly 22 times.We systematically studied the optical and electronic properties of the NV center as a function of an electron irradiation dose,where the detection sensitivity of magnetic fields was improved.With such samples with dense NV centers,a sub-pico-Tesla sensitivity in magnetic fields detection can be achieved with optimal controls and detections.
