Pub Date : 1999-04-01DOI: 10.1088/1004-423X/8/4/009
Guo Shu-quan, Yao Yu-shu, Xiong Yu-feng, Wu Fei, D. Cheng
A weak ferromagnetic transition has been observed for the T'-type compound Eu1.85Ca0.15CuO4. The samples were prepared by a high pressure (5 GPa) synthesis technique. Their transition temperature occurred at 27 K. At 5 K the residual magnetization was 0.033 emu/g, the coercive force was 6.3 x 10(4) A/m and the saturation field was larger than 1.6 x 10(5) A/m. A field cooling method is proposed as a very convenient way to determine the residual magnetization and coercive force. The compound Eu1.85Ca0.15CuO4 is suggested to use as a sensor to measure the remanant held of SQUID magnetometer.
{"title":"Weak ferromagnetic properties of Eu1.85Ca0.15CuO4","authors":"Guo Shu-quan, Yao Yu-shu, Xiong Yu-feng, Wu Fei, D. Cheng","doi":"10.1088/1004-423X/8/4/009","DOIUrl":"https://doi.org/10.1088/1004-423X/8/4/009","url":null,"abstract":"A weak ferromagnetic transition has been observed for the T'-type compound Eu1.85Ca0.15CuO4. The samples were prepared by a high pressure (5 GPa) synthesis technique. Their transition temperature occurred at 27 K. At 5 K the residual magnetization was 0.033 emu/g, the coercive force was 6.3 x 10(4) A/m and the saturation field was larger than 1.6 x 10(5) A/m. A field cooling method is proposed as a very convenient way to determine the residual magnetization and coercive force. The compound Eu1.85Ca0.15CuO4 is suggested to use as a sensor to measure the remanant held of SQUID magnetometer.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115628585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-04-01DOI: 10.1088/1004-423X/8/4/008
Zhang Qing-yu, Pan Zheng-Ying, Tang Jia-yong
The energetic atom deposition of thin Au/Au(100) film has been studied by molecular dynamics simulation using the Au-Au interatomic interaction potential with embedded atom method. By investigating the variation of coverage curves and Bragg diffraction intensities during the film growth, the transition of Stranski-Kranstanov growth mode to Frank-van der Merwe growth mode was observed with the increase of the incident energy of deposition atoms. The role of energetic atoms in the film growth is discussed by analyzing the transport properties of deposited atoms and the evolution of incident energy and substrate temperatures.
采用嵌入原子法，利用Au-Au原子相互作用势，对Au/Au(100)薄膜的高能原子沉积进行了分子动力学模拟研究。通过研究薄膜生长过程中覆盖曲线和Bragg衍射强度的变化，观察到随着沉积原子入射能量的增加，薄膜由Stranski-Kranstanov生长模式向Frank-van der Merwe生长模式转变。通过分析沉积原子的输运性质、入射能量和衬底温度的变化，讨论了高能原子在薄膜生长中的作用。
{"title":"Molecular dynamics simulation of energetic atom depositions of Au/Au(100) film","authors":"Zhang Qing-yu, Pan Zheng-Ying, Tang Jia-yong","doi":"10.1088/1004-423X/8/4/008","DOIUrl":"https://doi.org/10.1088/1004-423X/8/4/008","url":null,"abstract":"The energetic atom deposition of thin Au/Au(100) film has been studied by molecular dynamics simulation using the Au-Au interatomic interaction potential with embedded atom method. By investigating the variation of coverage curves and Bragg diffraction intensities during the film growth, the transition of Stranski-Kranstanov growth mode to Frank-van der Merwe growth mode was observed with the increase of the incident energy of deposition atoms. The role of energetic atoms in the film growth is discussed by analyzing the transport properties of deposited atoms and the evolution of incident energy and substrate temperatures.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114512135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-04-01DOI: 10.1088/1004-423X/8/4/007
Tian-you Fan, Xian-Fang Li, Ying-Fei Sun
This paper extends a moving screw dislocation theory in a conventional crystal to a one-dimensional hexagonal quasicrystal in the framework of the Landau theory. By introducing two functions and ψ which satisfy wave equations, respectively, a general solution is suggested in terms of and ψ. The analytical expressions for displacement and stress fields induced by a moving screw dislocation as well as the energy are found. The results obtained here when imposing the condition that the phason fields is absent reduce to those for a moving screw dislocation in a crystal.
{"title":"A moving screw dislocation in a one-dimensional hexagonal quasicrystal","authors":"Tian-you Fan, Xian-Fang Li, Ying-Fei Sun","doi":"10.1088/1004-423X/8/4/007","DOIUrl":"https://doi.org/10.1088/1004-423X/8/4/007","url":null,"abstract":"This paper extends a moving screw dislocation theory in a conventional crystal to a one-dimensional hexagonal quasicrystal in the framework of the Landau theory. By introducing two functions and ψ which satisfy wave equations, respectively, a general solution is suggested in terms of and ψ. The analytical expressions for displacement and stress fields induced by a moving screw dislocation as well as the energy are found. The results obtained here when imposing the condition that the phason fields is absent reduce to those for a moving screw dislocation in a crystal.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123052761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-04-01DOI: 10.1088/1004-423X/8/4/005
Tan Wei-han, Fan Wei
In view of the one-atom micromasers output sensitive to the interaction parameters, we propose a new multi-atom micromasers defined by passing multi-atom each time through the cavity regularly. Through analysis and numerical simulation, great progress has been made in the improvement of stability of mean photon number and variance of micromasers.
{"title":"Stability of multi-atom micromasers","authors":"Tan Wei-han, Fan Wei","doi":"10.1088/1004-423X/8/4/005","DOIUrl":"https://doi.org/10.1088/1004-423X/8/4/005","url":null,"abstract":"In view of the one-atom micromasers output sensitive to the interaction parameters, we propose a new multi-atom micromasers defined by passing multi-atom each time through the cavity regularly. Through analysis and numerical simulation, great progress has been made in the improvement of stability of mean photon number and variance of micromasers.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114955254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-04-01DOI: 10.1088/1004-423X/8/4/006
Chen Xiang-jun, Zhang Jing-qiao, Wang Yan-zhong
Effect of perturbations on spatial dark optical solitons is studied analytically with a novel direct perturbation approach for dark solitons. The problems of two-photon absorption and gain with saturation are reconsidered. The corresponding shifts of the soliton centers which have never been obtained by previous theories are given.
{"title":"Perturbed spatial dark solitons","authors":"Chen Xiang-jun, Zhang Jing-qiao, Wang Yan-zhong","doi":"10.1088/1004-423X/8/4/006","DOIUrl":"https://doi.org/10.1088/1004-423X/8/4/006","url":null,"abstract":"Effect of perturbations on spatial dark optical solitons is studied analytically with a novel direct perturbation approach for dark solitons. The problems of two-photon absorption and gain with saturation are reconsidered. The corresponding shifts of the soliton centers which have never been obtained by previous theories are given.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128044001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-04-01DOI: 10.1088/1004-423X/8/4/001
Ruan Hang-yu, Chen Yi-xin
The Painleve property, infinitely many symmetries and exact solutions of a (2+1)-dimensional nonlinear Schrodinger equation, which are obtained from the constraints of the Kadomtsev-Petviashvili equation, are studied in this paper. The Painleve property is proved by the Weiss-Kruskal approach, the infinitely many symmetries are obtained by the formal series symmetry method and the dromion-like solution which is localized exponentially in all directions is obtained by a variable separation method.
{"title":"Symmetries and dromion solution of a (2+1)-dimensional nonlinear Schrödinger equation","authors":"Ruan Hang-yu, Chen Yi-xin","doi":"10.1088/1004-423X/8/4/001","DOIUrl":"https://doi.org/10.1088/1004-423X/8/4/001","url":null,"abstract":"The Painleve property, infinitely many symmetries and exact solutions of a (2+1)-dimensional nonlinear Schrodinger equation, which are obtained from the constraints of the Kadomtsev-Petviashvili equation, are studied in this paper. The Painleve property is proved by the Weiss-Kruskal approach, the infinitely many symmetries are obtained by the formal series symmetry method and the dromion-like solution which is localized exponentially in all directions is obtained by a variable separation method.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132164590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-20DOI: 10.1088/1004-423X/8/3/010
Cheng Jin-hai, Wang Pei-nan, G. Zhao, Li Fuming
The emission spectrum of the 3Πi-3Πi (0-0) AlN band and some N+ and N emission lines have been studied in the visible region for the laser ablated plumes. The Stark-shift and Stark broadening were observed. The component species in the ablated plumes were analyzed by time of flight mass spectroscopy. The electron density and the temperature were calculated from the Stark-shift and Stark broadening of N (2D) emission line. The densities of AlN+, Al+, N+, AlN, N and Al were estimated by the mass spectra and the Saha equation.
{"title":"EMISSION AND MASS SPECTRAL ANALYSES OF LASER ABLATED AlN PLUMES","authors":"Cheng Jin-hai, Wang Pei-nan, G. Zhao, Li Fuming","doi":"10.1088/1004-423X/8/3/010","DOIUrl":"https://doi.org/10.1088/1004-423X/8/3/010","url":null,"abstract":"The emission spectrum of the 3Πi-3Πi (0-0) AlN band and some N+ and N emission lines have been studied in the visible region for the laser ablated plumes. The Stark-shift and Stark broadening were observed. The component species in the ablated plumes were analyzed by time of flight mass spectroscopy. The electron density and the temperature were calculated from the Stark-shift and Stark broadening of N (2D) emission line. The densities of AlN+, Al+, N+, AlN, N and Al were estimated by the mass spectra and the Saha equation.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114527466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-20DOI: 10.1088/1004-423X/8/3/002
Yao Yun-fei, Chen Zhang-jin
The double differential cross sections for electron impact ionization of helium at incident energies of 200 eV, 100 eV and 64.6 eV have been calculated in the BBK model. The present results are found to be in generally good agreement with the latest measurements of Roder et al. and the theoretical results of the convergent close-coupling method although some quantitative discrepancy remains.
{"title":"Double differential cross sections for electron impact ionization of helium","authors":"Yao Yun-fei, Chen Zhang-jin","doi":"10.1088/1004-423X/8/3/002","DOIUrl":"https://doi.org/10.1088/1004-423X/8/3/002","url":null,"abstract":"The double differential cross sections for electron impact ionization of helium at incident energies of 200 eV, 100 eV and 64.6 eV have been calculated in the BBK model. The present results are found to be in generally good agreement with the latest measurements of Roder et al. and the theoretical results of the convergent close-coupling method although some quantitative discrepancy remains.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130822861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-20DOI: 10.1088/1004-423X/8/3/005
Wang Chuan-kui, Wang Hong-song, Zhang Qing-gang
Numerical investigation of the electronic structure of a small closed quantum system fabricated on the two-dimensional electron gas forming on the interference between GaAs and AlxGa1-xAs is reported. The Kohn-Sham spin-density-functional theory is applied. Self-consistent results show that the quantum system assumes unequal numbers of electrons for spin up and spin down because of the existence of bound states. The profiles of effective potential energies for spin up and spin down electrons are then found to be very different, which will result in different transmission coefficients. It is notable that this spin polarization is caused by the geometry of the nanostructure.
{"title":"Spin polarization in a model quantum wire with a cross-section","authors":"Wang Chuan-kui, Wang Hong-song, Zhang Qing-gang","doi":"10.1088/1004-423X/8/3/005","DOIUrl":"https://doi.org/10.1088/1004-423X/8/3/005","url":null,"abstract":"Numerical investigation of the electronic structure of a small closed quantum system fabricated on the two-dimensional electron gas forming on the interference between GaAs and AlxGa1-xAs is reported. The Kohn-Sham spin-density-functional theory is applied. Self-consistent results show that the quantum system assumes unequal numbers of electrons for spin up and spin down because of the existence of bound states. The profiles of effective potential energies for spin up and spin down electrons are then found to be very different, which will result in different transmission coefficients. It is notable that this spin polarization is caused by the geometry of the nanostructure.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125976254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-20DOI: 10.1088/1004-423X/8/3/004
Chen Li-mei, Fu Hai-xiang, Cao Li, Wu Da–jin, Qiu Jun-lin
We apply the interpolation procedure to calculate the stationary probability distribution of the colored-loss-noise model of a single-mode dye laser operating above the threshold with correlation time τ covering a very wide range. By stochastic Runge-Kutta algorithm, we also carry out numerical simulations of steady-state properties. Comparing the results of the interpolation procedure and the unified colored-noise approximation with simulation results, we find that the agreement between the results of the interpolation procedure and the simulation results is much better than that of the unified colored-noise approximation when correlation time τ covers a range from moderate to large. We conclude that the interpolation procedure really improve the accuracy of predictions for this system.
{"title":"Stationary probability distribution for colored-loss-noise model of a single-mode dye laser","authors":"Chen Li-mei, Fu Hai-xiang, Cao Li, Wu Da–jin, Qiu Jun-lin","doi":"10.1088/1004-423X/8/3/004","DOIUrl":"https://doi.org/10.1088/1004-423X/8/3/004","url":null,"abstract":"We apply the interpolation procedure to calculate the stationary probability distribution of the colored-loss-noise model of a single-mode dye laser operating above the threshold with correlation time τ covering a very wide range. By stochastic Runge-Kutta algorithm, we also carry out numerical simulations of steady-state properties. Comparing the results of the interpolation procedure and the unified colored-noise approximation with simulation results, we find that the agreement between the results of the interpolation procedure and the simulation results is much better than that of the unified colored-noise approximation when correlation time τ covers a range from moderate to large. We conclude that the interpolation procedure really improve the accuracy of predictions for this system.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132586109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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