The insulator-metal(I-M)transition in colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_(3) has been studied by electrical transport,magnetization and electron spin resonance(ESR)measurements.Around the I-M tran...The insulator-metal(I-M)transition in colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_(3) has been studied by electrical transport,magnetization and electron spin resonance(ESR)measurements.Around the I-M transition,the ESR signal shows a crossover from paramagnetic resonance line to ferromagnetic resonance line,which implies a coexistence of localized small polarons and itinerant carriers during the I-M transition.Based on the concept of‘small polaron collapse’,a two-phase model is proposed to quantitatively describe the electrical transport behaviour across the insulator-metal transition.The calculations of resistivity in different applied magnetic fields have close trends with the experimental data,which strongly proves that the I-M transition results from the collapse of small polarons and two phases coexist during the transition.展开更多
In this paper, by the three series theorem of m-negatively associated(m-NA,in short) random variables and the truncation method of random variables, we mainly investigated the strong convergence properties for partial...In this paper, by the three series theorem of m-negatively associated(m-NA,in short) random variables and the truncation method of random variables, we mainly investigated the strong convergence properties for partial sums of m-NA random variables.In addition, the Khintchine-Kolmogorov convergence theorem and Kolmogorov-type strong law of large numbers for m-NA random variables are also obtained. The results obtained in the paper generalize some corresponding ones for independent random variables and some dependent random variables.展开更多
The transport properties of La_(0.67)Sr_(0.33)Mn_(O3) (LSMO) epitaxial films on differently orientated LaAlO3 substrates have been studied. The as-deposited films with different orientation exhibit different transport...The transport properties of La_(0.67)Sr_(0.33)Mn_(O3) (LSMO) epitaxial films on differently orientated LaAlO3 substrates have been studied. The as-deposited films with different orientation exhibit different transport behaviours. The resistivity of the films on the (100) and (110) substrates undergoes a metal--insulator transition while the resistivity of the film on the (111) substrate is insulator-like. This is attributed to the discrepancy of oxygen deficiency in the samples which is influenced by the lattice mismatch between the film and the substrate. After being annealed at 700℃ in 1-atm flowing pure oxygen for half an hour, all films have the same resistivity behaviour as the bulk LSMO, which may be important for future applications.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19934003the Research Fund for the Doctoral Program of Higher Education.
文摘The insulator-metal(I-M)transition in colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_(3) has been studied by electrical transport,magnetization and electron spin resonance(ESR)measurements.Around the I-M transition,the ESR signal shows a crossover from paramagnetic resonance line to ferromagnetic resonance line,which implies a coexistence of localized small polarons and itinerant carriers during the I-M transition.Based on the concept of‘small polaron collapse’,a two-phase model is proposed to quantitatively describe the electrical transport behaviour across the insulator-metal transition.The calculations of resistivity in different applied magnetic fields have close trends with the experimental data,which strongly proves that the I-M transition results from the collapse of small polarons and two phases coexist during the transition.
基金Supported by the Natural Science Foundation of Anhui Province（1508085J06） the Key Projects for Academic Talent of Anhui Province（gxbj ZD2016005） the Students Innovative Training Project of Anhui University（201610357001）
文摘In this paper, by the three series theorem of m-negatively associated(m-NA,in short) random variables and the truncation method of random variables, we mainly investigated the strong convergence properties for partial sums of m-NA random variables.In addition, the Khintchine-Kolmogorov convergence theorem and Kolmogorov-type strong law of large numbers for m-NA random variables are also obtained. The results obtained in the paper generalize some corresponding ones for independent random variables and some dependent random variables.
基金Supported by the National Natural Science Foundation of China under Grant No.19934003the Research Fund for the Doctoral Program of Higher Education and the Chinese Academy of Sciences.
文摘The transport properties of La_(0.67)Sr_(0.33)Mn_(O3) (LSMO) epitaxial films on differently orientated LaAlO3 substrates have been studied. The as-deposited films with different orientation exhibit different transport behaviours. The resistivity of the films on the (100) and (110) substrates undergoes a metal--insulator transition while the resistivity of the film on the (111) substrate is insulator-like. This is attributed to the discrepancy of oxygen deficiency in the samples which is influenced by the lattice mismatch between the film and the substrate. After being annealed at 700℃ in 1-atm flowing pure oxygen for half an hour, all films have the same resistivity behaviour as the bulk LSMO, which may be important for future applications.
