We investigate the electronic and magnetic properties of the diluted magnetic semiconductors Zn1-xMnxS（001） thin films with different Mn doping concentrations using the total energy density functional theory. The en...We investigate the electronic and magnetic properties of the diluted magnetic semiconductors Zn1-xMnxS（001） thin films with different Mn doping concentrations using the total energy density functional theory. The energy stability and density of states of a single Mn atom and two Mn atoms at various doped configurations and different magnetic coupling state were calculated. Different doping configurations have different degrees of p-d hybridization, and because Mn atoms are located in different crystal-field environment, the 3d projected densities of states peak splitting of different Mn doping configurations are quite different. In the two Mn atoms doped, the calculated ground states of three kinds of stable configurations are anti-ferromagnetic state. We analyzed the 3d density of states diagram of three kinds of energy stability configurations with the two Mn atoms in different magnetic coupling state. When the two Mn atoms are ferromagnetic coupling, due to d-d electron interactions, density of states of anti-bonding state have significant broadening peaks. As the concentration of Mn atoms increases, there is a tendency for Mn atoms to form nearest neighbors and cluster around S. For such these configurations, the antiferromagnetic coupling between Mn atoms is energetically more favorable.展开更多
Epitaxial （0001）-oriented Zn1-xCoxO （x= 0.01, 0.05 and 0.1） thin films were grown on c-sapphire substrates by pulsed laser deposition. The XRD analysis, optical transmittance and XPS measurements revealed that the...Epitaxial （0001）-oriented Zn1-xCoxO （x= 0.01, 0.05 and 0.1） thin films were grown on c-sapphire substrates by pulsed laser deposition. The XRD analysis, optical transmittance and XPS measurements revealed that the Co2＋ substituted Zn2＋ ions were incorporated into the lattice of ZnO in Zn1-xCoxO thin films. The electrical properties measurements revealed that the Co concentration had a non- monotonic influence on the electrical properties of the Zn1-xCoxO thin films due to the defects resulted from imperfections induced by Co substitution. The resistivity remarkably increased and the carrier concentration remarkably decreased in Zn1-x CoxO thin films after oxygen annealing at 600 ℃ under 15 Pa O2 pressure for 60 mins. Room-temperature ferromagnetic was observed and the ferromagnetic Co amount was smaller than the nominal Co concentration for Zn1-xCoxO samples before oxygen annealing. After oxygen annealing, the Zn1-x CoxO thin films exhibited paramagnetic behavior. It is suggested that the room-temperature ferromagnetic ofZn1-x CoxO thin films may attribute to defects or carriers induced mechanism.展开更多
Zn1-xCuxO thin films were synthesized by the radio frequency （RF） magnetron sputtering technique using a ZnO target containing different pieces of small Cu-chips. X-ray diffraction （XRD） and scanning electron micr...Zn1-xCuxO thin films were synthesized by the radio frequency （RF） magnetron sputtering technique using a ZnO target containing different pieces of small Cu-chips. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were employed to analyze the crystalline and microstructure of the film, and X-ray photoelectron spectroscopy （XPS） was used to establish the bonding characteristics and oxidation states of copper inside the ZnO host. Room temperature （RT） ferromagnetism was observed in the Znl-xCuxO films by a Quantum Design superconducting quantum interference device （SQUID） and the saturation magnetic moment of the films was found to decrease with the increase in Cu content.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.60776039 and No.60406005）, the Natural Science Foundation of Beijing （No.3062016）, and the School Foundation of Beijing Jiaotong University.
文摘We investigate the electronic and magnetic properties of the diluted magnetic semiconductors Zn1-xMnxS（001） thin films with different Mn doping concentrations using the total energy density functional theory. The energy stability and density of states of a single Mn atom and two Mn atoms at various doped configurations and different magnetic coupling state were calculated. Different doping configurations have different degrees of p-d hybridization, and because Mn atoms are located in different crystal-field environment, the 3d projected densities of states peak splitting of different Mn doping configurations are quite different. In the two Mn atoms doped, the calculated ground states of three kinds of stable configurations are anti-ferromagnetic state. We analyzed the 3d density of states diagram of three kinds of energy stability configurations with the two Mn atoms in different magnetic coupling state. When the two Mn atoms are ferromagnetic coupling, due to d-d electron interactions, density of states of anti-bonding state have significant broadening peaks. As the concentration of Mn atoms increases, there is a tendency for Mn atoms to form nearest neighbors and cluster around S. For such these configurations, the antiferromagnetic coupling between Mn atoms is energetically more favorable.
基金Funded by New Century Excellent Talents in University(No.NCET-10-0662)International Science and Technology Cooperation Project of Hubei Province(No.2010BFA017)International Science&Technology Cooperation Program of China(No.2011DFA52650)
文摘Epitaxial （0001）-oriented Zn1-xCoxO （x= 0.01, 0.05 and 0.1） thin films were grown on c-sapphire substrates by pulsed laser deposition. The XRD analysis, optical transmittance and XPS measurements revealed that the Co2＋ substituted Zn2＋ ions were incorporated into the lattice of ZnO in Zn1-xCoxO thin films. The electrical properties measurements revealed that the Co concentration had a non- monotonic influence on the electrical properties of the Zn1-xCoxO thin films due to the defects resulted from imperfections induced by Co substitution. The resistivity remarkably increased and the carrier concentration remarkably decreased in Zn1-x CoxO thin films after oxygen annealing at 600 ℃ under 15 Pa O2 pressure for 60 mins. Room-temperature ferromagnetic was observed and the ferromagnetic Co amount was smaller than the nominal Co concentration for Zn1-xCoxO samples before oxygen annealing. After oxygen annealing, the Zn1-x CoxO thin films exhibited paramagnetic behavior. It is suggested that the room-temperature ferromagnetic ofZn1-x CoxO thin films may attribute to defects or carriers induced mechanism.
基金National Natural Science Foundation of China (Nos.10275047,10575073)the Natural Science Foundation of Jiangsu Province of China (03KJB140116)
文摘Zn1-xCuxO thin films were synthesized by the radio frequency （RF） magnetron sputtering technique using a ZnO target containing different pieces of small Cu-chips. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were employed to analyze the crystalline and microstructure of the film, and X-ray photoelectron spectroscopy （XPS） was used to establish the bonding characteristics and oxidation states of copper inside the ZnO host. Room temperature （RT） ferromagnetism was observed in the Znl-xCuxO films by a Quantum Design superconducting quantum interference device （SQUID） and the saturation magnetic moment of the films was found to decrease with the increase in Cu content.
