磁性隧道结中自旋相关的隧穿输运

全面回顾和总结了磁性隧道结中自旋相关的隧穿这一研究领域的理论和实验方面的最新研究进展。讨论了影响磁性隧道结的自旋极化和隧穿磁电阻的各种因素及反映铁磁层和铁磁／绝缘层界面电子结构在隧穿中重要作用的理论模型和近期实验，同时也讨论了绝缘势垒和铁磁／绝缘层界面中的无序性在隧穿过程中对自旋极化与磁电阻效应的影响。     

极化效应对AlN/GaN共振隧穿二极管电流特性的影响

本文采用半经验紧束缚能带理论,通过自洽计算薛定谔方程和泊松方程研究了AlN/GaN共振隧穿二极管中极化效应对电流的影响.结果发现,极化效应导致电流曲线发生不对称性,并影响电流的共振电压位置,这与实验报道的结果相一致.并且随着极化电荷的增加,在一定的偏压条件下,只能观测到一个子能级隧穿或者根本没有负微分电阻现象发生.     

极化效应对AIN／GaN共振隧穿二极管电流特性的影响

本文采用半经验紧束缚能带理论，通过自洽计算薛定谔方程和泊松方程研究了A1N／GaN共振隧穿二极管中极化效应对电流的影响。结果发现，极化效应导致电流曲线发生不对称性，并影响电流的共振电压位置，这与实验报道的结果相一致。并且随着极化电荷的增加，在一定的偏压条件下，只能观测到一个子能级隧穿或者根本没有负微分电阻现象发生。     

学术自由讨论是科学发展的前提——评黄志洵新著《超光速研究新进展》

2002年夏季，黄志洵教授的著作《超光速研究新进展》出版。书中介绍关于超光速研究的重要理论和实验进展，并按三个部分叙述不同领域的有关研究，如超光速理论与实验、反常色散与负群速（王力军等人的光脉冲超光速传播实验）、波粒二象性理论的成就和问题、EPR思维、中微子质量研究进展等。这是一本内容新颖、丰富、生动的好书，对读者颇具吸引力。文章强调指出，学术上的自由讨论是科学发展的前提。     

学术自由讨论是科学发展的前提——评黄志洵新著《超光速研究新进展》

2002年夏季，黄志洵教授的作《超光速研究新进展》出版。书中介绍关于超光速研究的重要理论和实验进展，并按三个部分叙述不同领域的有关研究，如超光速理论与实验、反常色散与负群速（王力军等人的光脉冲超光速传播实验）、波粒二象性理论的成就和问题、EPR思维、中微子质量研究进展等。这是一本内容新颖、丰富、生动的好书，对读颇具吸引力。章强调指出，学术上的自由讨论是科学发展的前提。     

多晶硅/氧化硅/多晶硅非平面结构中Fowler-Nordheim隧穿及氧化层退化研究(英文)

Fowler-Nordheim隧穿被广泛应用于EEPROM和闪存中的擦除操作。多晶硅到多晶硅的F-N隧穿具有较高的隧穿效率。本论文基于分栅闪存存储器的结构,对于多晶硅/隧穿氧化层/多晶硅非平面结构的F-N隧穿及其引起的氧化层退化进行了研究。相比于平面结构,非平面结构显示出更高的F-N隧穿效率,且隧穿效率还可通过降低氧化层厚度或者增加预热氧化处理的方法进一步提高。较低的F-N隧穿电流密度显示出较慢的隧穿氧化层退化速率。降低氧化层厚度或者增加热氧化处理也可减缓隧穿氧化层的退化。另外,论文还讨论了研究结果对于改善分栅闪存擦除特性以及耐久性的意义。     

许驭科研组与他们的原创性发明

<正>许驭科研组的十大新发现前沿科学家许驭等科研人员历经19年辛勤研究,取得丰硕研究成果,有关研究者归纳为许驭原创基础研究十大新科学发现。1、许驭第一次验证、发现超光速粒子正、反中微子互不湮没、反电中微子的反隧穿量子效应,以及宇宙线初级μ子衰变后的反中微子引发天然质子     

爱因斯坦的物体速度不能大于c的结论正确吗?

本文所讨论的问题是超光速现象是否存在,这在作者所引的黄志洵著的两本书中已有了肯定的回答。本刊认为,就超光速实验而言,也属于计量的范畴,速度是基本单位长度米和时间秒的导出量,测量光速的实验已进行了300余年。但测量超光速的实验并非易事。狭义相对论的光速不变原理有两个含义:一是在任何情况下,往返光速相等;二是光速不可超越。2009年,《宇航学报》第一期发表了林金等人的一篇论文:"爱因斯坦光速不变假设的判决性实验检验",实验证明:卫星和地面站之间存在1米/秒量级的相对速度时,会造成西安临潼站与乌鲁木齐站之间"往"和"返"两个单程信号通过的时间差在1.5纳秒量级,观测结果的不确定度在0.01纳秒量级。由此证明爱因斯坦的狭义相对论中的光速不变原理在具有相对运动情况下不成立。由此可见,如果在速度更快的星体上进行实验,超光速测量就不难实现。     

物理光学的若干进展

就物理光学方面的一系列理论和实验研究，如GoosHnchen位移、FTIR现象、负折射率、太赫超光速实验、光子静质量测量等做了评述和讨论。指出近年来的研究显示了消失波现象的重要性，例如消失波可造成超光速传播，且常有新方法和新测量结果；介绍了物理光学在相关领域的技术创新和应用实例；讨论了光子有静止质量的可能性及光频标准和光频测量的历史和新的进展     

介观电路中量子逻辑门的研究

在介观电路的研究中,提出了用超晶格量子阱如何实现基本量子门及量子开关,同时展示了在超晶格量子阱中量子信息位的具体转化过程.对垒阱中电子波动行为及隧穿情况做了详细的理论分析,并给出如何避免隧穿效应的具体条件.     

Hidden possibilities in soliton switching through tunneling in erbium doped birefringence fiber with higher order effects

In this paper, coupled higher order nonlinear Schrödinger–Maxwell–Bloch equations are studied for the ultrashort pulse propagation in erbium-doped birefringent fiber system. Lax pair is constructed for the CHNLS–MB system. Through the Darboux method and symbolic computation, analytic two-soliton solution is obtained. To analyze the specific problem, we design an optimal system by properly choosing the special form of variable coefficients. Here, using obtained two-soliton solution, tunneling of femtosecond soliton through barrier and well is investigated. While solitons are passing through barrier and well, some unexpected behavior is observed and hidden possibilities in switching action through tunneling is investigated.     

Analytical modeling of field-induced interband tunneling-effect transistors and its application

In the room-temperature I-V characteristics of field-induced interband tunneling-effect transistors (FITETs), negative-differential conductance (NDC) characteristics as well as negative-differential transconductance (NDT) characteristics have been observed. The key operation principle of this quantum-tunneling device is the field-induced interband tunneling. To include the effect of interband tunneling, we have developed an analytical equation of interband tunneling current. Due to the inherent SOI-MOSFET structure of the FITET, the current equation of MOSFET has also been included in the analytical equation of the FITET. By comparing the calculated data from these two current components with the measured data, an additional excess tunneling current component has been introduced in the final analytical equation of the FITET. SPICE simulation results with this analytical model have shown good agreements with the experimental results. Also, this analytical model has been applied to verify the functionality of a simple digital logic gate such as XOR and four-level parity checker made by one FITET.     

氧化镁磁隧道结磁电阻效应的研究进展

概述了近年来关于氧化镁磁隧道结磁电阻效应的最新研究进展,介绍了势垒层厚度、偏压、温度以及微结构等因素对磁电阻效应的影响.氧化镁磁隧道结的磁电阻效应与铁磁电极层和势垒层间的界面化学态与磁状态密切相关,势垒层厚度、偏压和温度等对磁电阻效应的影响关系表现出与传统氧化铝磁隧道结不同的变化特点.根据氧化镁磁隧道结磁电阻效应的研究状况,对其将来的发展进行了展望.     

The influence of the combination of coherent and sequential tunneling on the tunneling magnetoresistance in a ferromagnet-metal-insulator-ferromagnet tunneling junction

We apply the spin-polarized free-electron model to theoretically study the tunneling magnetoresistance (TMR) in a ferromagnet-metal-insulator-ferromagnet tunneling junction. In the presence of the metallic layer, the tunneling of electrons for current flow through the junction can be divided into two components: the coherent tunneling and the sequential tunneling components. Our calculations show that the attenuated TMR oscillation is well fitted by a damped oscillation function with an exponential decay if only the coherent tunneling is considered. But, if the sequential tunneling is included in the calculations, the behavior of the attenuated TMR oscillation slightly deviates from the damped oscillation function.     

Motion Characterizations of Lateral Micromachined Sensor Based on Stroboscopic Measurements

In this paper, we illustrate the capabilities of the Planar Motion Analyzer (PMA) with a study of the dynamic behavior of a micromachined structure. Dynamic characterizations and measurement settings are also demonstrated. The optical measurement system uses the light-emitting diode (LED) based vibration measurement technique for imaging, and then measuring the lateral resonant frequency and sensor displacements, as well. The PMA analyzes in-plane vibrations of a MEMS device under a clear microscope. Its working principle is based on the stroboscopic principle. Based on this principle, characterization results in both time and frequency domains can be accurately generated and analyzed. Our device example for the measurement is a tunneling-based micro-resonator, which was fabricated using the Backside Released SOI process. The tunneling behavior of the sensor can be observed by controlling the motion of the tunneling tip towards the opposing electrode with a typical gap of 10 Aring. This very small gap can be easily achieved by the Bode measurement of PMA for shifting the LED-strobe flashes at a small increment of phase angle over the whole motion of the sensor. In other words, smaller motions of the tip will be easily achieved, when the number of shots per period are larger. For our tunneling measurement, the phase angle shift is 0.5deg with 720 shots per period. The lateral moving proof mass is suspended by the folded springs, and its tip protrudes to an opposing electrode by means of electrostatic forces. The tunneling current has been observed to be exponentially increasing, when the tunneling gap is decreasing. However, the further large current is actually a contacting current, when the mechanical contact happens between the tunneling tip and the opposing electrode. The resonant frequency of the device is ~5 kHz obtained from the Bode measurement     

Effect of viscoelastic interface on three-dimensional static and vibration behavior of laminated composite plate

In this study, static and free vibration analysis of laminated cross-ply rectangular plate with special emphasis on incorporating viscoelastic interface is investigated using three-dimensional theory of elasticity. The laminated plate is assumed to be simply-supported at four edges and is subjected to uniform pressure at the top surface. State space technique is used along the plate thickness to investigate the space dependent behavior where as time dependent behavior can be discussed by solving first order differential equation of sliding displacement at the viscoelastic interfaces. Numerical results depicts that the present method converges rapidly and good agreement is exist between the present results and the published results. Moreover, the effects of elastic and viscous interfaces, time, aspect ratio and length to thickness ratio on the bending and vibration behavior of laminated plate are studied.     

Thermal Conductivity of Glasses Induced by Nuclear Quadrupole Interaction at Ultra Low Temperatures

It is investigated how nuclear degrees of freedom of tunneling system (TS) inherent in amorphous solids influence its acoustic properties. It was shown in our previous papers that below 10 mK nuclear quadrupole interaction breaks down the coherent tunneling. This phenomenon results in appearance of the quasi-gap in the distribution function for the tunneling amplitude splitting. The quasi-gap is responsible for the plateau in the temperature dependence of the real part of a dielectric permittivity or speed of sound. In this paper we are interested in ultrasonic absorption and thermal conductivity which are intimately connected. We demonstrate that there exists a temperature interval in a millikelvin region where the sound absorption behavior changes drastically from the behavior predicted by the standard tunneling model (STM). In particular, the sound absorption increases approximately by an order of magnitude. Since in the millikelvin region the heat transport is due to acoustic phonons, the thermal conductivity also should demonstrate a strong increase as compared to standard tunneling model. The application of a strong magnetic field is known to restore the coherent tunneling and the standard distribution for the tunneling splitting amplitude. Thus, one can expect that in a strong magnetic field the thermal conductivity should drop in the temperature interval where the coherent tunneling was initially destroyed.     

Room temperature observation of size dependent single electron tunneling in a sub-2 nm size tunable Pt nanoparticle embedded metal-oxide-semiconductor structure

In this paper we report size dependent single electron tunneling behavior at room temperature in a metal-oxide-semiconductor structure with uniformly sized Pt nanoparticles embedded in an Al(2)O(3) dielectric. The sub-2 nm size Pt nanoparticles sandwiched between the Al(2)O(3) layers are deposited by a unique tilted target sputter deposition technique which produces metal nanoparticles as small as 0.5 nm with narrow size distributions at room temperature. The charging behavior of these nanoparticles shows clear single electron tunneling peaks due to the Coulomb blockade effect. Moreover, the average single electron addition energy and height of the single electron tunneling current strongly depend on the size of the Pt nanoparticle. These controllable single electron tunneling behaviors suggest a new route for fabrication of single electron devices.     

Nanometer sized polymer based Schottky junctions

The aim of this work was to realize and characterize rectifying junctions with nanometer thickness based on conducting polymers. Various monolayer films were deposited onto different flat graphite electrodes in order to obtain the Schottky interfaces. The second electrical contact was realized by approaching the monolayer film with sharp tip electrode at nanometric distances, in order to create tunneling barriers. A couple of hundred of junctions were realized following this procedure. The investigated junctions have shown rectifying behavior on the current/voltage characteristics in the 96% of the cases. The analysis of the current/voltage characteristics revealed the typical behavior of Schottky barriers. The ideality factor and the Schottky barrier of the junctions were calculated. Moreover, a linear relationship between the threshold voltage and the tunneling barrier width was revealed. In our knowledge, this is the first report of a Schottky junction realized with a monolayer of polymer film.