Growth of Indium Nanorods by Magnetron Sputtering

Indium nanorods are grown on silicon substrates by using magnetron-sputtering technique. Film morphologies and nanorod microstructure are investigated by using scanning electron microscopy, high-resolution transmission electron microscopy （HRTEM）, and x-ray diffraction. It is found that the mean diameter of the nanorods ranges from 30nm to 100nm and the height ranges from 30nm to 200nm. The HRTEM investigations show that the indium nanorods are single crystals and grow along the [100] axis. The nanorods grow from the facets near the surface undulation that is caused by compressive stress in the indium grains generated during grain coalescence process. For low melting point and high diffusivity metal, such as bismuth and indium, this spontaneous nanorod growth mechanism can be used to fabricate nanostructures.     

超导体MgB2中临界电流密度与磁场和温度之间的关系

用SQUID磁强计测量了在不同温度一直到5T的MgB2磁滞回线,确定了下临界磁场和样品的退磁因子.临界电流密度对磁场和温度的关系可以用一个简单的函数拟合.钉扎力密度符合Kramer标度律,但是峰值位置随温度移动.     

熔融织构块材和单晶YBa2CU3O7在63—75K的磁驰豫性质

本文研究了熔融织构块材和单晶YBa2Cu3O7在液氮温区63－75K的磁驰豫性质。在此温区常数ωa是与温度相关的，平均有效结合能作为电流密度的函数和Zeldov模型一致。     

贵金属Ag中光学和磁光性质的研究实验

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Synthesis and photoluminescence study on ZnO nano-particles

A new technique, namely low pressure sputtering, has been developed to fabricate Zn nanoparticles, with a subsequent oxidation to synthesize ZnO nanoparticles in the ambient atmosphere at 500$\,^{\circ}$C. The synthesized ZnO nanoparticle has a size of 6--8~nm with a preferred orientation of $c$-axis. The produced ZnO nanoparticles have a good UV photoluminescence (PL) emission energy of 3.349 eV with a significant enhancement of donor--acceptor pair emission located at 3.305 eV which implies a number of donor and acceptor bounded excitons existing in the synthesized ZnO nano particles. The near band edge PL emission of the fabricated ZnO is dominated by the bounded excitons at 10~K.     

Possible Evidence for Spin-Transfer Torque Induced by Spin-Triplet Supercurrents

The mutual interplay between superconductivity and magnetism in superconductor/ferromagnet heterostructures may give rise to unusual proximity effects beyond current knowledge. Especially, spin-triplet Cooper pairs could be created at carefully engineered superconductor/ferromagnet interfaces. Here we report a giant proximity effect on spin dynamics in superconductor/ferromagnet/superconductor Josephson junctions. Below the superconducting transition temperature T_C, the ferromagnetic resonance field at X-band(~9.0 GHz) shifts rapidly to a lower field with decreasing temperature. In strong contrast, this phenomenon is absent in ferromagnet/superconductor bilayers and superconductor/insulator/ferromagnet/superconductor multilayers. Such an intriguing phenomenon can not be interpreted by the conventional Meissner effect. Instead, we propose that the strong influence on spin dynamics could be due to spin-transfer torque associated with spin-triplet supercurrents in ferromagnetic Josephson junctions with precessing magnetization.     

Spontaneous Hillock Growth on Indium Film Surface

Uniformly distributed indium hillocks are grown on silicon substrates by dc magnetron sputtering. The morphologies and the microstructures have been investigated by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and x-ray diffraction （XRD）. From the TEM and SEM images, we find that, at the earlier stage, the grain coalescent process dominates. This coalescent process induces a larger compressive stress. We believe that the drive force for hillock growth comes from this compressive stress. Under this compressive stress, the grain locating in the middle of several grains are extruded from these grains, and then a hillock forms with the increasing deposition time. For low melting point and high diffusion coefficient metal, such as bismuth and indium, this spontaneous-hillock growth mechanism can be used to fabricate well aligned nanostructures.     

Experimental observation of interlayer perpendicular standing spin wave mode with low damping in skyrmion-hosting [Pt/Co/Ta]10 multilayer

An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting [Pt/Co/Ta]₁₀ multilayer by measuring the time-resolved magneto-optical Kerr effect. The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers. This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode, but within higher frequency range. Besides, the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field. This work expounds the potential application of the [heavy-metal/ferromagnetic-metal]_n multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes, relatively low damping, and skyrmion states, simultaneously.     

高温超导体中磁通涡旋的量子隧道效应——TlBaCaCuO化合物磁弛豫的实验研究

本文报道了ＴｌＢａＣａＣｕＯ超导体（２２１２,２２２３单相,多晶及薄膜材料）中磁弛豫现象的实验结果。从实验上证实了通量运动由热激活到非热激活机制的转变。实验中得到的与温度无关的磁弛豫速率与由通量运动量子隧道效应理论计算结果相一致。同时讨论了各向异性和磁场对磁通的量子漂移速率的影响     

高温超导体中磁通涡旋的量子隧道效应——TlBaCaCuO化合物磁弛豫的实验研究

本文报道了ＴｌＢａＣａＣｕＯ超导体（２２１２，２２２３单相，多晶及薄膜材料）中磁弛豫现象的实验结果。从实验上证实了通量运动由热激活到非热激活机制的转变。实验中得到的与温度无关的磁弛豫速率与由通量运动量子隧道效应理论计算结果相一致。同时讨论了各向异性和磁场对磁通的量子漂移速率的影响