利用真空热蒸发的方法,在云母片上制备分子层数可控的锌卟啉(ZnTPP)分子薄膜.随着分子层数的增多,ZnTPP薄膜的光致荧光(Photoluminescence,PL)光谱从单体特征渐变为二聚体特征;原子力显微镜(Atomic Force Microscope,AFM)的图像中,ZnTP...利用真空热蒸发的方法,在云母片上制备分子层数可控的锌卟啉(ZnTPP)分子薄膜.随着分子层数的增多,ZnTPP薄膜的光致荧光(Photoluminescence,PL)光谱从单体特征渐变为二聚体特征;原子力显微镜(Atomic Force Microscope,AFM)的图像中,ZnTPP分子团簇成纳米尺度的岛状结构,非真空环境导致纳米岛进一步聚集,从而使二聚体特征峰荧光强度激增;样品荧光寿命表明在非真空环境下分子的二聚体衰减通道比例显著增加.展开更多
The influence of surface/interface roughness on the magnetic properties of Fe/Ni multilayers is investigated.Two methods are employed to tune the film roughness:one varies the substrate temperature,and the other pre-d...The influence of surface/interface roughness on the magnetic properties of Fe/Ni multilayers is investigated.Two methods are employed to tune the film roughness:one varies the substrate temperature,and the other pre-deposits a Ag underlayer on the MgO substrate.For films with higher roughness,a marked rise in coercivity is observed.Three factors are discussed to be mainly responsible for the coercivity rise,involving the formation of pinholes,the reduction of exchange coupling between Fe and Ni layers,and Fe-Ni alloying at interfaces.展开更多
The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and impr...The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L10 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe49Pt51/Fe bi-layers by their exchange coupling.展开更多
Thin Mn（2 nm）/Al（2 nm） bilayers serving as buffer layers have been prepared prior to the deposition of MnAl films. The ferromagnetic T-phase forms in the buffer layers at an optimum substrate temperature. As a tem...Thin Mn（2 nm）/Al（2 nm） bilayers serving as buffer layers have been prepared prior to the deposition of MnAl films. The ferromagnetic T-phase forms in the buffer layers at an optimum substrate temperature. As a template it induces the growth of following MnAl film. Compared with the case of film without buffer layer, the growth of nonferromagnetic phase is suppressed and the structural and magnetic properties of MnAl film are improved. Weak dipolar inter-grain coupling is revealed in the MnAl film, and the magnetic reversal process is dominated by magnetic moment rotation.展开更多
[Fe/Ni]N multilayered structure grows epitaxially on the single crystalline MgO substrate. Due to the different directions of magnetic easy axes of Fe and Ni and the strong strain, large anisotropy dispersion is assum...[Fe/Ni]N multilayered structure grows epitaxially on the single crystalline MgO substrate. Due to the different directions of magnetic easy axes of Fe and Ni and the strong strain, large anisotropy dispersion is assumed. According to the layer model, the magnetization of Fe and Ni layers cannot follow each easy axis because of exchange coupling, and then the anisotropies are averaged out. The reduction of the effective anisotropy enhances with the decrease of periodic thickness. Thus, the coercivity of [Fe/Ni]N multilayers reduces with decreasing periodic thickness.展开更多
We investigate the structure and exchange coupling in TbFeCo/FePt bilayer films. It is found that FePt has the L10 structure and the easy axis of the FePt film is perpendicular to the film plane. Results of the vibrat...We investigate the structure and exchange coupling in TbFeCo/FePt bilayer films. It is found that FePt has the L10 structure and the easy axis of the FePt film is perpendicular to the film plane. Results of the vibrating sample magnetometer and the magneto-optical Kerr effect measurements show a strong perpendicular exchange coupling between the ferrimagnetic TbFeCo layer and the hard ferromagnetic FePt layer. The magnetization direction of each layer and the process of magnetization reversal are discussed in detail. The switching field dependence on the exchange coupling has been modelled by micromagnetic simulation and the interlayer coupling constant is about -0.9 erg/cm^2 according to this simulation.展开更多
Noble metal nanoparticles exhibit unique surface plasmon resonance dependent optical properties.On this basis,gold nanoparticles(AuNPs)encapsulated in metal–organic frameworks(MOFs)can form AuNPs@MOFs composites to m...Noble metal nanoparticles exhibit unique surface plasmon resonance dependent optical properties.On this basis,gold nanoparticles(AuNPs)encapsulated in metal–organic frameworks(MOFs)can form AuNPs@MOFs composites to modulate the optical properties of fluorescent molecules,which is less reported.In this paper,based on the fluorescence enhancement effect of AuNPs on 2-(2-hydroxyphenyl)-1H-benzimidazole(HPBI)molecules,zeolitic imidazolate framework-8(ZIF-8)crystals with structural stability were introduced.AuNPs@ZIF-8 exhibited a significantly pronounced fluorescence enhancement of the HPBI molecules.In addition,by comparing the fluorescence characteristics of the HPBI molecules adsorbed on AuNPs@ZIF-8 and those captured in AuNPs@ZIF-8,we found that the ZIF-8 can act as a spacer layer with highly effective near-field enhancement.All our preliminary results shed light on future research on the composite structures of noble metal particles and MOFs for fluorescent probes and sensing applications.展开更多
文摘利用真空热蒸发的方法,在云母片上制备分子层数可控的锌卟啉(ZnTPP)分子薄膜.随着分子层数的增多,ZnTPP薄膜的光致荧光(Photoluminescence,PL)光谱从单体特征渐变为二聚体特征;原子力显微镜(Atomic Force Microscope,AFM)的图像中,ZnTPP分子团簇成纳米尺度的岛状结构,非真空环境导致纳米岛进一步聚集,从而使二聚体特征峰荧光强度激增;样品荧光寿命表明在非真空环境下分子的二聚体衰减通道比例显著增加.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51071046,61078030,11074046,11174056,11274113the National Basic Research Program of China(2009CB929201)the Characterization Facility,University of Minnesota,a member of the NSF-funded Materials Research Facilities Network(www.mrfn.org)via the NSF MRSEC program under award number DMR-0819885.
文摘The influence of surface/interface roughness on the magnetic properties of Fe/Ni multilayers is investigated.Two methods are employed to tune the film roughness:one varies the substrate temperature,and the other pre-deposits a Ag underlayer on the MgO substrate.For films with higher roughness,a marked rise in coercivity is observed.Three factors are discussed to be mainly responsible for the coercivity rise,involving the formation of pinholes,the reduction of exchange coupling between Fe and Ni layers,and Fe-Ni alloying at interfaces.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60490290,60678008 and 50771032)the National Basic Research Program of China (Grant No 2009CB929201)the Science Foundation of the Science and Technology Committee of Shanghai (Grant No 06DJ14007)
文摘The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L10 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe49Pt51/Fe bi-layers by their exchange coupling.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60490290, 60678008, 10604016, 50771032,and 50771033)the National Basic Research Program of China (Grant No. 2009CB929201)
文摘Thin Mn（2 nm）/Al（2 nm） bilayers serving as buffer layers have been prepared prior to the deposition of MnAl films. The ferromagnetic T-phase forms in the buffer layers at an optimum substrate temperature. As a template it induces the growth of following MnAl film. Compared with the case of film without buffer layer, the growth of nonferromagnetic phase is suppressed and the structural and magnetic properties of MnAl film are improved. Weak dipolar inter-grain coupling is revealed in the MnAl film, and the magnetic reversal process is dominated by magnetic moment rotation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60490290, 60678008, 10604016, 50771032 and 50771033, the National Basic Research Program of China （2009CB929201）. We-thank Professor Wang Jian-Ping for constructive discussion. The Characterization Facility and Institute of Rock Magnetism Facilities are acknowledged for structural and magnetic measurements.
文摘[Fe/Ni]N multilayered structure grows epitaxially on the single crystalline MgO substrate. Due to the different directions of magnetic easy axes of Fe and Ni and the strong strain, large anisotropy dispersion is assumed. According to the layer model, the magnetization of Fe and Ni layers cannot follow each easy axis because of exchange coupling, and then the anisotropies are averaged out. The reduction of the effective anisotropy enhances with the decrease of periodic thickness. Thus, the coercivity of [Fe/Ni]N multilayers reduces with decreasing periodic thickness.
基金Supported by the National Natural Science Foundation under Grant Nos 60490290, 10404019, and 10374019, the Science and Technology Committee of Shanghai under Grant No 04D214001, and the Ministry of Education of China.
文摘We investigate the structure and exchange coupling in TbFeCo/FePt bilayer films. It is found that FePt has the L10 structure and the easy axis of the FePt film is perpendicular to the film plane. Results of the vibrating sample magnetometer and the magneto-optical Kerr effect measurements show a strong perpendicular exchange coupling between the ferrimagnetic TbFeCo layer and the hard ferromagnetic FePt layer. The magnetization direction of each layer and the process of magnetization reversal are discussed in detail. The switching field dependence on the exchange coupling has been modelled by micromagnetic simulation and the interlayer coupling constant is about -0.9 erg/cm^2 according to this simulation.
文摘Noble metal nanoparticles exhibit unique surface plasmon resonance dependent optical properties.On this basis,gold nanoparticles(AuNPs)encapsulated in metal–organic frameworks(MOFs)can form AuNPs@MOFs composites to modulate the optical properties of fluorescent molecules,which is less reported.In this paper,based on the fluorescence enhancement effect of AuNPs on 2-(2-hydroxyphenyl)-1H-benzimidazole(HPBI)molecules,zeolitic imidazolate framework-8(ZIF-8)crystals with structural stability were introduced.AuNPs@ZIF-8 exhibited a significantly pronounced fluorescence enhancement of the HPBI molecules.In addition,by comparing the fluorescence characteristics of the HPBI molecules adsorbed on AuNPs@ZIF-8 and those captured in AuNPs@ZIF-8,we found that the ZIF-8 can act as a spacer layer with highly effective near-field enhancement.All our preliminary results shed light on future research on the composite structures of noble metal particles and MOFs for fluorescent probes and sensing applications.
