Papers by Keyword: Spin

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Authors: David M. Schrader
Abstract: Dipositronium, Ps2, was recently prepared [1]. This is significant because: • It is the first laboratory observation of a molecule that contains more than one positron; • It is the most symmetrical molecule possible; • It is the most non-rigid (floppiest) molecule possible; • The interval between the theoretical establishment of its existence [2] and its laboratory observation [1] is inordinately long – 60 years; and • An extension of the technology developed for the Ps2 observation may soon lead to an observation of the Bose-Einstein condensation of positronium and the development of a gamma ray laser. We briefly discuss the symmetry of Ps2 and how an understanding of it will underlie its characterization in the future. Ps2O and CPs2 might be the next two-positron compounds to be prepared and characterized in the laboratory. A discussion of the contrasting eigenstates of these two molecules is given. An understanding of these states is required in order to identify them.
Authors: Pavel Osmera, Imrich Rukovansky
Abstract: We tried to combine the basic principle of grammatical evolution with vortex-ring-fractal structures of atoms to create new molecule structures. This approach combines knowledge of evolutionary optimization with physical chemistry.
Authors: Anatoly Druzhinin, Igor Ostrovskii, Yuriy Khoverko, Sergij Yatsukhnenko
Abstract: Study the magnetic properties of Si<B,Ni> whiskers, the concentration of which corresponds to a dielectric and metal side of metal-insulator transition, is performed. Percolation laws of the magnetic clusters formation, that is important for development of spintronic devices, are considered.
Authors: Qing Lin, Yun He, Jian Mei Xu, Hai Fu Huang, Rui Jun Wang
Abstract: The cyano-bridged complexes [MA(en)x]y[Fe(CN)6]z·nH2O(MA=Co2+、Gu2+) have been synthesized. In the multi-metal compound [Co(en)3] [Fe(CN)6] ·6.1H2O was prepared. Infrared spectra with stretching vibration CN = 2117.27 cm-1 illustrates that there exists the bridged cyanide on the compound; the Curie temperature Ө is -8.23117 K, indicating the magnetic interaction between the metal ions in the compound is very weak.In the multi-metal compound CuII3[FeIII(CN)6]2·3NH3·6H2O, we shows firstly the coexistence of ferromagnetic order and spin-glass order.The irreversibility in the MFC/MZFC and the relaxation of MZFC suggest that the magnetic system can be visualized as containing a ferromagnetic cluster of spin below Tc, mixed with small spin-glass clusters formed below temperature Tg less than Tc. The observed magnetic properties are explained with a ferromagnetic-spin-glass phase model.
Authors: Yun Bo Shi, Hui Xue, Zong Min Ma, Huan Zhang, Jun Tang, Chen Yang Xue, Jun Liu, Yan Jun Li
Abstract: The atomic spin interaction is very important for understanding the superficially magnetic feature of nanostructure at atomic level. Magnetic exchange force microscopy (MExFM) is an innovative means of measuring surface spin force. But it is difficult to separate the surface topography and spin information. We develop the magnetic exchange force microscopy using ferromagnetic resonance (FMR-MExFM). The theoretical and experimental results demonstrate that this method can separate the two kinds of information effectively. Here, in order to obtain the high sensitivity in detecting the ferromagnetic resonance, we fabricate the microwave irradiation device to optimize the position between the device and the cantilever. We have succeeded in observing the ferromagnetic resonance effect and determining its resonant frequency using the homemade microwave irradiation device and the network analyzer. This research is very important for developing FMR-MExFM and novel magnetic sensor, detecting the magnetic information, etc.
Authors: A. Bournel, P. Dollfus, P. Bruno, P. Hesto
Authors: Hui Li, Masaki Maekawa, A. Miyashita, Atsuo Kawasuso
Abstract: We briefly review the spin-polarized positron annihilation experiments on some ferromagnets (Fe, Co, Ni, Gd, Co2MnSi, Co2MnAl and NiMnSb) using positron beams generated with 68Ge-68Ga sources. The differential DBAR spectra between majority and minority spin electrons are well interpreted by the first principles band structure calculation. This further provides information about the half-metallicity of the Heusler alloys. The surfaces of Fe, Co and Ni are more negatively spin-polarized, that is, there are more majority than minority spin electrons. To explain the observed spin polarization quantitatively, detailed theoretical calculations and further experiments are required.
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