一例具有单分子磁体行为的单核钴-氮氧自由基异自旋配合物

合成并表征了一例2p-3d异自旋配合物[Co(hfac)_(2)(NIT-Pyz Me-Ph CHO)](1),其中hfac=六氟乙酰丙酮,NIT-PyzMe-PhCHO=2-(3-(1H-咪唑-1-亚甲基)苯甲醛)-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物。配合物1是单核结构,Co^(Ⅱ)离子与直接配位的氮氧基团之间存在强的反铁磁耦合。此外,与磁弛豫相关的频率依赖的虚部信号证实了其单分子磁体行为。

异自旋中心三自由基分子的磁性设计

采用量子化学DFTUB3LYP方法 ,在 6 31G(d)基组水平上讨论了以 1,3,5 苯为铁磁耦合单元的异自旋中心三自由基体系 .结果表明 :对于异自旋三自由基体系 ,形成异自旋后对称性降低使部分占据的近简并轨道能级劈裂值增大 ,反铁磁耦合作用普遍增强 .由两个同自旋和一个异自旋中心构成的三自由基若保持较好的对称性 (C2v)可望表现铁磁耦合 .在通常情况下这类分子服从已有规律 :ΔEPOMO小 ,ΔED Q大 ,表现为稳定的四重态基态 ,且其稳定性与苯环 2 ,4 。

异自旋中心有机铁磁体分子设计

采用量子化学从头算ＵＨＦ方法对系列异自旋三自由基体系的基态自旋耦合规律进行研究，并对组成不同的异自旋（ｈｅｔｅｒｏｓｐｉｎ）三自由基进行了系统的比较，为新型有机磁性材料的实验合成提供了理论依据．

具有磁弛豫和荧光性能的氮氧自由基-稀土离子环形双核

选用手性氮氧自由基与稀土离子反应,成功组装了2例2p-4f异自旋内消旋配合物[Ln(hfac)3((R)-MePP-Ph-NIT)]2,其中Ln=Eu(1)、Dy(2),hfac=六氟乙酰丙酮,(R)-MePP-Ph-NIT=2-(4-((R)-tert-butyl-2-methylpiperazine-1-carboxylate)phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide。在配合物中,氮氧自由基配体连接2个稀土离子形成环形双核结构。配合物1展现出铕离子的特征荧光。在配合物2中,磁弛豫相关的频率依赖的虚部信号说明了其单分子磁体的特性。

Spin-Tunneling Time in Ferromagnetic/Semiconductor/Ferromagnetic Three-Terminal Heterojunction in the Presence of Rashba Spin-Orbit Coupling

We study theoretically the transmission coefficients and the spin-tunneling time in ferromagnetic/semiconductor/ferromagnetic three-terminal heterojunction in the presence of Rashba spin-orbit interaction, in which onedimensional quantum waveguide theory is developed and applied. Based on the group velocity concept and the particle current conservation principle, we calculate the spin-tunneling time as the function of the intensity of Rashba spinrblt coupling and the length of the semiconductor. We find that as the length of the semiconductor increases, the spintunneling time does not increase linearly but shows behavior of slight oscillation, i;brthermore, with the increasing of the soin-orbit coupling, the spin-tunneling time increases.

Anisotropy and Magnetic Field Effects on Entanglement of a Two-Spin (1/2,1) Mixed-Spin Heisenberg XY Chain

We study the entanglement in anisotropie （1/2,1） mixed-spin Heisenberg XY model under the presence of an external magnetic field at thermal equilibrium. By adjusting the anisotropic parameter and the magnetic field, one is able to obtain entanglement at higher temperature. We find the evidence of the quantum phase transition in the model and observe that the quantum phase transition point at low temperature moves toward weak magnetic field with the increase of the anisotropic parameter.

Magnetic Properties of Spin-1／2 Quantum Heisenberg Ferromagnet with Spatially Anisotropy

The spin-1/2 quantum Heisenberg ferromagnet with anisotropic spin exchange interactions in three dimensions are investigated by means of the Green's function method. In the Tyablikov approximation, the correlation function s, the magnetization, and the susceptibilities are computed. The magnetic properties of this model are found to be dependent of anisotropy.

Quantum Communication in Spin Chain with Multiple Spin Exchange Interaction

The transmission of quantum states in the anisotropic Heisenberg XXZ chain model with three-spin exchange interaction is studied. The average fidelity is used to evaluate the state transfer. It is found that quantum communication can be enhanced by the anisotropic coupling and multiple spin interaction. Such spin model can reduce the time required for the perfect state transmission where the fidelity is unity. The maximally entangled Bell states can be generated and separated from the whole quantum systems.

Physical Problems of Quantum Calculation： A Novel Approach

The manuscript deals with the possibility of application of collective behavior of quantum particles to realize the quantum calculation procedure. The above collective behavior is likely resulted from interelectron correlations, characteristic for strongly correlated systems containing atoms with unoccupied 3d-, 4f- and 5f- shells. Among such systems can be the heterospin systems, complexes of paramagnetic ions of transition metals with organic radicals, because for such objects, spin-spin interaction between unpaired electron spins of different paramagnetic centers is typical. To apply the aforementioned possibility for the organization of real quantum calculations, it is necessary to synthesize such paramagnetic molecules （paramagnetic clusters）, where the entangled states will be realized naturally by self-organization of atoms incorporated in these molecules, i.e., without additional external effect of q-bits on the system. The specified self-organization may be due to intramolecular processes and, in particular, intramolecular rearrangement called valence tautomerism, which leads to heterogeneous magnetic states, i.e., to phase layering in paramagnetic cluster owing to interelectron correlations. The states realized during the phase layering can be used for coding the digits. Since such states correspond to specific structures of para-magnetic molecule, they can exist as much as long under certain conditions. In turn, it means that the account of the interelectron correlations, which take place in strongly correlated compounds, allows （at least, in principle） one to create elementary quantum bit of the information capable of modeling the elementary logical operations. Creation of a network of such quantum bits combined in a certain sequence should be considered as a practical step on a way to experimental realization of the idea of quantum computer creation. The group consisting of three quantum points can make the basis of quantum computer. In such a gate, quantum points can be connected via the interaction modeled by spin-spin interaction, characteristic for ABX system in NMR spectroscopy. The tunnel effect, which can be easily realized and controlled, can act as an indicator of bonding in such a block. The calculation procedure can be organized assuming that the initial state of the group corresponds to 1. Infringement of such a state indicates to zero （or, on the contrary）. Thus, the calculation in the binary system becomes organized. The creation of a network on the basis of combination of such processors in certain sequence should be considered as a practical step on a way to experimental realization of the idea of the quantum computer creation.

Zero-Magnetic-Field Spin Splitting of Polaron＇s Ground State Energy Induced by Rashba Spin-Orbit Interaction

We study theoretically the ground state energy of a polaron near the interface of a polar-polar semiconductor by considering the Rashba spin-orbit （SO） coupling with the Lee-Low-Pines intermediate coupling method. Our numerical results show that the Rashba SO interaction originating from the inversion asymmetry in the heterostructure splits the ground state energy of the polaron. The electron area/density and vector dependence of the ratio of the SO interaction to the total ground state energy or other energy composition are obvious. One can see that even without any external magnetic field, the ground state energy can be split by the Rashba SO interaction, and this split is not a single but a complex one. Since the presents of the phonons, whose energy gives negative contribution to the polaron＇s, the spin-splitting states of the polaron are more stable than electron＇s.

Mean-Field Studies of a Mixed Spin-3/2 and Spin-2 and a Mixed Spin-3/2 and Spin-5/2 Ising System with Different Anisotropies

The magnetic properties of a mixed spin-3/2 and spin-2 and a mixed spin-3/2 and spin-5/2 Ising ferromag- netic system with different anisotropies are studied by means of mean-field theory （MFT）. The dependence of the phase diagram on single-ion anisotropy strengths is studied too. In the mixed spin-3/2 and spin-2 Ising model, besides the second-order phase transition, the first order-disorder phase transition and the tricritical line are found. In the mixed spin-3/2 and spin-5/2 Ising model, there is no first-order transition and trieritical line.

Thermal Entanglement of an XY Two-Qutrit Spin Chain with Dzialoshinski—Moriya Interaction

The effect of Dzialoshinski-Moriya(DM)interaction on thermal entanglement of an XY two-qutrit spinchain is investigated.We find that DM interaction and the anisotropy parameter can enhance quantum thermal entanglementto a maximal value individually.However,when both of them take large values,the entanglement is notenhanced,but is destroyed.Our analysis will shed some light on the understanding of the effect of the DM interactionon thermal entanglement of an XY two-qutrit spin chain.

Magnetism of One-Dimensional Dipolar-Interaction Spin Chains with Perpendicular Anisotropy

We have investigated the magnetism of one-dimensional dipolar-interaction spin chains with perpendicular anisotropy by simulation. The behaviors of the magnetizations and the orientation correlations change dramatically as the anisotropy increases to the critical value. The domain length can be controlled by adjusting the temperature and the external field as well as the anisotropy. These properties are interesting and arise from the competition between the anisotropy and the interaction along the chain.

Macroscopic Quantum Coherence in an Antiferromagnetic Spin Chain with Biaxial Anisotropy

Instanton configurations of （1＋1）-dimensions in an antiferromagnetic biaxial-anisotropy-spin-chain are obtained explicitly in the strong anisotropy limit, which interpolate between degenerate equilibrium orientations of the Neel vector along easy axis and are seen to be responsible for quantum tunneling. Macroscopic quantum coherence of the domain walls is demonstrated in terms of the instantons.

Anomalous Kondo-Switching Effect of a Spin-Flip Quantum Dot Embedded in an Aharonov-Bohm Ring

We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm （AIR） ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian. Based on the slave-boson mean-field theory, we find that in this system the persistent current （PC） sensitively depends on the parity and size of the AB ring and can be tuned by the spin-flip scattering （R）. In the small AB ring, the PC is suppressed due to the enhancing R weakening the Kondo resonance. On the contrary, in the large AB ring, with R increasing, the peak of PC firstly moves up to max-peak and then down. Especially, the PC phase shift of π appears suddenly with the proper value of R, implying the existence of the anomalous Kondo effect in this system. Thus this system may be a carldidate for quantum switch.

Influence of Ground State Spin of Projectile-Target on Fission Anisotropies

Fission fragment anisotropies have been investigated for various systems produced in heavy-ion reactions at near and sub-barrier energies. In particular, special attention has been paid to the entrance channel dependence of fragment angular anisotropies. The results of our analysis of the fragment angular anisotropies induced by boron, carbon, and oxygen ions on Thorium and Neptunium targets as well as Fluorine ions on Neptunium target indicate strong dependence of fragment anisotropies on the channel spin, in consistence with the predication of the pre-equilibrium model.

A new pathway towards all-electric spintronics:electric-field control of spin states through surface/interface effects

Manipulation of spin states via purely electric means forms the research branch "all-electric spintronics".In this paper,we briefly review recent progress relating to the all-electric spintronics,including electric-field control of Rashba spin-orbit coupling,magnetic anisotropy,exchange bias,ferromagnetism,and other forms of magnetoelectric coupling.Special focus is given to surface/interface systems,including semiconductor(oxide) heterostructures,magnetic/nonmagnetic surfaces,semiconductor-metal interfaces,and other nanostructures,which can be good candidates for functional materials for spintronic.

Organic-ferromagnetic hetero-structures with spin transport properties and fundamental physical effects

Organic spintronics refers to control spin dependent transport through organic materials.In the last two decades,extraordinary development has been achieved for organic-spintronics.A series of theoretical and experimental studies have been done to reveal the mechanisms of spin dependent transport properties.The theoretical analysis is based on the non-equilibrium Green's function formalism provides a mathematical framework for solving the transmission coefficients in the Landauer formula from atomistic first principles without any phenomenological parameters.In this article,we provide a brief theoretical review on organic spintronics devices and device physics therein.

The codes of matter and their applications

The elements in the periodic table are the building blocks used to form substances with different compositions. Nevertheless, it is the properties of substances that are decisive for their existence and practical applications. Searching for new class of materials with exotic properties has always been challenging because of the complexity of both the theoretical and the experimental approaches developed so far. Here, we propose that the three ubiquitous and paramount attributes of all existing matter charge(Q), spin(S) or rotational motion, and linear motion(K) can be used to account for the formation of different types of matter/materials and their properties that have been or will be known to us. The three attributes or original codes can produce six primary codes which can further produce another sixty codes. The physical meanings represented by each code are unlocked. The table consisting of the 60 codes is introduced as the table of properties of codes of matter. We demonstrate that these codes can be used as building blocks to form new properties and new materials. Many new types of quasiparticles and new classes of materials with exotic properties of Q, S and K are predicted. Their possible experimental realizations are proposed. The possible applications of the codes of matter in other fields such as elementary particles, photonics and chemistry are briefly discussed. We know that there should be more new materials and new electronic, spin and photonic states to be discovered, but we do not know what they are. The codes of matter clearly reveal to us how many and what they are and how easily we can recognize what they are. Experimental and theoretical exploration for new forms of matter, new quasiparticles, or new electronic and spin states, or new states of photon or properties of light, as well as macroscopic entities with exotic properties represented by the codes of matter, is imminent.

Spin-Wave Analysis of the Spin-1 Two-Dimensional Frustrated Heisenberg Antiferromagnet with the Single-Ion Anisotropy

In this paper, the lowtemperature properties of the spin1 twodimensionM frustrated Heisenberg antifer romagnet with the singleion anisotropy are investigated on a square lattice by using the spinwave theory. The influence of the frustration and anisotropy is found in the thermodynamics of the model, such as the temperature dependence of the staggered magnetization and specific heat. For some selected values of the frustration and anisotropy parameters, the results for the specific heat are compared with those of existing theories and numerical estimates. Within a spinwave analysis, we have found the evidence for an intermediate magnetically disorder phase to separate the Nel and collinear phases.