稀磁ZnO纳米颗粒的生长和性能

利用Zn、Fe、Mn、Co的铜铁试剂盐为前驱体,胺为表面包裹剂,在200℃N2保护下生长了2%的过渡金属离子掺杂的ZnO稀磁纳米晶体,研究了纳米晶体的结构、形态、光学和磁学性能。所有ZnO纳米晶体均为近圆形的颗粒,晶体结构为六角纤锌矿结构,无其他氧化物相的析出,但过渡金属离子的掺入使纳米颗粒的尺寸增大。在掺杂纳米颗粒的吸收谱和发射谱中均可以观察到明显的激子吸收和发射峰,所有纳米颗粒在温度高于43K时只有顺磁性。     

Determination of the magnetic anisotropy constant of Cu/Fe/SiO2/Si by a magneto-optical Kerr effect susceptometer

The magneto-optical Kerr effect susceptometry technique is proposed to determine the uniaxial magnetic anisotropy(UMA) constant Ku. The magnetic properties of Cu/Fe/SiO2/Si grown by dc magnetron sputtering were investigated. The in-plane uniaxial magnetic anisotropy was probed by the magneto-optical Kerr effect(MOKE). The value of UMA, Ku= 2.5×103J/m3, was simulated from the field dependence of ac susceptibility along the hard axis according to the Stoner–Wohlfarth(S–W) model, which is consistent with Ku= 2.7×103J/m3 calculated from the magnetic hysteresis loops. Our results show that the magneto-optical Kerr effect susceptometry can be employed to determine the magnetic anisotropy constant owing to its high sensitivity.     

Cd_(0.96)Zn_(0.04)S/Cd_(0.97)Mn_(0.03)S/Cd_(0.96)Zn_(0.04)S多层纳米线中s-d交换作用的研究

以氧化铝纳米孔为模板,采用直流电化学沉积的方法制备了Cd_(0.96)Zn_(0.04)S/Cd_(0.97)Mn_(0.03)S/Cd_(0.96)Zn_(0.04)S量子阱纳米线阵列,并系统研究了该纳米线阵列在不同温度和不同磁场下的电学输运特性.随着外磁场的变化,样品表现出共振传输特性.通过量子阱理论对实验现象进行了分析,直接得到了稀磁层Cd_(0.97)Mn_(0.03)S中s-d交换作用常数N_0α的定量结果.研究发现该交换作用常数随温度具有e~(-1/T)的变化趋势.     

空芯纳米氧化亚铜颗粒的制备及其光学性质

采用微波辐照法,以葡萄糖为还原剂还原Cu^2＋离子,制备出空芯纳米氧化亚铜颗粒,并研究了表面活性剂六次甲基四胺对颗粒形貌的影响．制得的样品利用X射线衍射仪（XRD）、扫描电镜（SEM）及紫外分光光度计（UV-vis）进行表征．结果表明,用微波辐照法制备的氧化亚铜颗粒具有空芯球状结构;随着表面活性剂浓度的减少,构成空芯球的纳米颗粒由球状过渡为片状,且粒径逐渐增大．氧化亚铜颗粒属于立方晶型,其吸收峰出现在430nm附近,对应的禁带宽度约为2．58eV,尺寸效应导致了明显的蓝移现象．     

干涉法测量音叉振动

采用干涉法对音叉受迫振动的位移振幅、速度振幅以及音叉振动与外加周期性驱动力的相频关系做了测量与探究.实验结果表明,位移共振频率与速度共振频率近似相等;音叉达到共振时,音叉振动与外加周期性驱动力存在π/2的相位差.利用干涉的方法可对音叉受迫振动的位移振幅、速度振幅以及音叉振动与外加周期性驱动力的相频关系同时进行研究,并且可观测到调节信号源频率至共振频率过程中相位差的改变,以及达到共振时施加外在扰动后相位差偏离π/2而后恢复的过程.     

Magnetic properties of DNA-templated Co/Cu naonoparticle chains

<正>According to ultraviolet(UV)-vis absorption spectra recorded in the DNA metallization process,DNA-templated Co/Cu binary nanoparticle chains are fabricated by incubating genome DNA of paralichthys olivaceus muscle in CoCl_2 and CuCl_2 mixture solution for 20 hours and reducing the complex for 2 hours.Transmission electron microscopy observation indicates that Co and Cu nanoparticles with 20 nm in diameter were randomly dispersed on the DNA template. The superconducting quantum interference device(SQUID) measurements display that the magnetic interaction between cobalt particles is greatly decreased by the copper particle.With increasing copper content,the coercivity of the systems enhance from 9 Oe to 100 Oe(1 Oe=79.5775 A/m).     

Determination of the magnetic anisotropy constant of Cu/Fe/Si02/Si by a magneto-optical Kerr effect susceptometer

The magneto-optical Kerr effect susceptometry technique is proposed to determine the uniaxial magnetic anisotropy （UMA） constant Ku. The magnetic properties of Cu/Fe/SiO2/Si grown by dc magnetron sputtering were investigated. The in-plane uniaxial magnetic anisotropy was probed by the magneto-optical Kerr effect （MOKE）. The value of UMA, Ku = 2.5 x 103 J/m3, was simulated from the field dependence of ac susceptibility along the hard axis according to the Stoner-Wohlfarth （S-W） model, which is consistent with Ku = 2.7~ 103 J/m3 calculated from the magnetic hysteresis loops. Our results show that the magneto-optical Kerr effect susceptometry can be employed to determine the magnetic anisotropy constant owing to its high sensitivity.     

Magnetization reversal in Fe48Pt34B34 magnetic foils

Exchange-spring magnet L1-FePt/(Fe₂B+α-Fe) is fabricated by flash annealing a melt-spun Fe₄₈Pt₃₄B₃₄ foil. A coercivity of 8500 Oe (1 Oe = 79.5775 A/m), squareness (M_r/M_s) of 0.70, saturation magnetization of 10.2 kGs (1 Gs = 10^-4 T) and an effective anisotropy K_eff =2.0 × 10⁷ ergs/cm³ are obtained. A two-step magnetization reversal feature is characterized in this paper. An exchange bias phenomenon is also observed in a low saturation field.