The magneto-optical Kerr effect of the HfO2/Co/HfO2/A1 multilayer structure is investigated in this work, and an ob- vious cavity enhancement of the Kerr response for the HfO2 semiconductor is found both theoretically...The magneto-optical Kerr effect of the HfO2/Co/HfO2/A1 multilayer structure is investigated in this work, and an ob- vious cavity enhancement of the Kerr response for the HfO2 semiconductor is found both theoretically and experimentally. Surprisingly, a maximum value of about -3 of the polar Kerr rotation for s-polarized incident light is observed in our experiment. We propose that this improvement on the Kerr effect can be attributed to the multiple reflection and optical interference in the cavity, which can also be proved by simulation using the finite element method.展开更多
The low-temperature magnetic order behaviors of perovskite oxide CaCu_(3)Ti_(4)O_(12)(CCTO)ceramics prepared by different methods are discussed.X-ray diffraction,scanning electron microscope,x-ray photoelectron spectr...The low-temperature magnetic order behaviors of perovskite oxide CaCu_(3)Ti_(4)O_(12)(CCTO)ceramics prepared by different methods are discussed.X-ray diffraction,scanning electron microscope,x-ray photoelectron spectroscopy,and direct current(DC)magnetization are used to characterize the structures,microscopic morphologies,valence states,and magnetic properties of the samples.The results show that the magnetic behaviors of CCTO ceramics are very sensitive to the preparation process.The quenched CCTO ceramic and CCTO powders grown in a molten salt crystal,which contain much more oxygen vacancies and Ti^(3+),show the coexistence of weak ferromagnetic order and antiferromagnetic order below the Neel temperature.It suggests that the bound magnetopolaron formed by oxygen vacancies and Ti^(3+)ion composite defects are responsible for the weak ferromagnetic order at low temperature.展开更多
Nd0.7 Sr0.3MnO3 ceramics with secondary phases were prepared by ball-milling and post heat- treatment at 1623 K for 3,7 and 13h,respectively.The results from x-ray diffraction and energy dispersed spectroscopy show th...Nd0.7 Sr0.3MnO3 ceramics with secondary phases were prepared by ball-milling and post heat- treatment at 1623 K for 3,7 and 13h,respectively.The results from x-ray diffraction and energy dispersed spectroscopy show that some secondary phases are introduced and grow gradually with sintering time.These secondary phases have significant effects on the ac transport.For all the samples,the real part of impedance (Zr) decreases with increasing frequency and the Zr peak moves to a higher temperature.Interestingly,for a given frequency the Zr peak decreases with sintering time.However,for samples B and C which were sintered for a longer time than sample A,an additional Zr peak appears at a higher temperature and gradually increases with sintering time.The reposition of trapped charges in phase/grain boundaries or secondary phases is supposed to be responsible for the unusual relaxation process.展开更多
基金supported by the National Key Project of Fundamental Research of China(Grant Nos.2012CB932304 and 2010CB923404)the National Natural Science Foundation of China(Grant Nos.50971070 and U1232210)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The magneto-optical Kerr effect of the HfO2/Co/HfO2/A1 multilayer structure is investigated in this work, and an ob- vious cavity enhancement of the Kerr response for the HfO2 semiconductor is found both theoretically and experimentally. Surprisingly, a maximum value of about -3 of the polar Kerr rotation for s-polarized incident light is observed in our experiment. We propose that this improvement on the Kerr effect can be attributed to the multiple reflection and optical interference in the cavity, which can also be proved by simulation using the finite element method.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504227 and 51971128)the Program of Shanghai Academic/Technology Research Leader,China(Grant No.20XD1401800)the Project of the Science and Technology Commission of Shanghai Municipality,China(Grant No.19020501000).
文摘The low-temperature magnetic order behaviors of perovskite oxide CaCu_(3)Ti_(4)O_(12)(CCTO)ceramics prepared by different methods are discussed.X-ray diffraction,scanning electron microscope,x-ray photoelectron spectroscopy,and direct current(DC)magnetization are used to characterize the structures,microscopic morphologies,valence states,and magnetic properties of the samples.The results show that the magnetic behaviors of CCTO ceramics are very sensitive to the preparation process.The quenched CCTO ceramic and CCTO powders grown in a molten salt crystal,which contain much more oxygen vacancies and Ti^(3+),show the coexistence of weak ferromagnetic order and antiferromagnetic order below the Neel temperature.It suggests that the bound magnetopolaron formed by oxygen vacancies and Ti^(3+)ion composite defects are responsible for the weak ferromagnetic order at low temperature.
基金Supported by the Program for New Century Excellent Talents in University under Grant No NCET-08-0674.
文摘Nd0.7 Sr0.3MnO3 ceramics with secondary phases were prepared by ball-milling and post heat- treatment at 1623 K for 3,7 and 13h,respectively.The results from x-ray diffraction and energy dispersed spectroscopy show that some secondary phases are introduced and grow gradually with sintering time.These secondary phases have significant effects on the ac transport.For all the samples,the real part of impedance (Zr) decreases with increasing frequency and the Zr peak moves to a higher temperature.Interestingly,for a given frequency the Zr peak decreases with sintering time.However,for samples B and C which were sintered for a longer time than sample A,an additional Zr peak appears at a higher temperature and gradually increases with sintering time.The reposition of trapped charges in phase/grain boundaries or secondary phases is supposed to be responsible for the unusual relaxation process.
