共查询到20条相似文献,搜索用时 62 毫秒
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在一代Technicolor(TC)模型中计算了PGBs(PseudoGoldenstoneBosons)对高能e+e-→tt过程的单圈量子效应.给出了重整化的形状因子和矩阵元.计算了PGBs对总截面前后不对称参数AFB和左右不对称参数ALR的虚贡献,结果表明选取适当的参数值,新物理对以上可测量的贡献最大分别可达:-12.3%、-3.3%和-11.7%.在下一代对撞机上这一理论结果能为TC理论打开实验的窗口.同样的计算表明PGBs对e+e-→bb过程的单圈贡献小于-1.0%. 相似文献
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高能重离子碰撞中K+/π+比例的显著升高被认为是夸克、胶子等离子体形成的一个可能信号.基于参加者核子模型和次级粒子形成时间的概念,本文对Si(14.5A GeV/c)与Au的中心碰撞进行了Monte Carlo模拟计算.在计算中考虑了如下次级碰撞过程:πN→K+Y、ππ→KK以及πN的单电荷交换反应.本文的计算结果表明:由这些次级碰撞过程导致的末态的K+/π+比例的升高不足以解释BNL的E802组观测到的实验数据. 相似文献
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提出了一个讨论铁磁/反铁磁双层膜中的交换偏置及矫顽场温度特性的物理模型,该模型,假设铁磁层为具有单畴各向异性的单畴膜而反铁磁层由许多相互独立具有多晶各向异性的颗粒组成,其温度依赖性主要来源于系统态的热不稳定,包括反铁磁颗粒易轴取向的热涨落和相关磁学量的温度依赖性等。计算结果表明其交换偏置随温度的增加非线性地减少而其矫顽场在体阻截温度处达极大值,且其体阻截温度随反铁磁颗粒粒径的增加而增加。我们的计算结果和相关实验结果一致,通过本的讨论,我们建议通过铁磁膜耦合上大粒径硬反铁磁颗粒膜可获得高交换偏置、低矫顽场且近独立于温度的相关磁学器件。 相似文献
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The structure dependence of exchange bias in ferromagnetic/antiferromagnetic (FM/AF) bilayers has been investigated in detail by extending Slonczewski's 'proximity magnetism' idea. Here three important parameters are discussed for FM/AF bilayers, i.e. interracial bilinear exchange coupling J1, interracial biquadratic (spin-flop) exchange coupling J2 and antiferromagnetic layer thickness tAF. The results show that both the occurrence and the variety of the exchange bias strongly depend on the above parameters. More importantly, the small spin-flop exchange coupling may result in an exchange bias without the interracial bilinear exchange coupling. However, in general, the spin-flop exchange coupling cannot result in the exchange bias. The corresponding critical parameters in which the exchange bias will occur or approach saturation are also presented. 相似文献
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研究了交换偏置双层膜中界面存在二次以及双二次交换耦合下反铁磁磁矩转动及其交换各向异性.结果表明,其反铁磁膜中的磁矩转动存在可逆“恢复行为”、不可逆“半转动行为”、不可逆“倒转行为”以及不可逆“半倒转行为”四种情形,四种情形的出现强烈地依赖于界面二次、双二次耦合以及反铁磁膜厚度.其中可逆恢复行为情况下,系统出现交换偏置,而不可逆的半转、半倒转以及倒转情形,系统不出现交换偏置.特别地,在界面处仅存在双二次耦合的情形下,其界面双二次耦合常数J2≤0.1 σ关键词:
反铁磁自旋结构
交换各向异性
界面双二次耦合
交换偏置 相似文献
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采用蜂窝陶瓷蓄热换热器实现高温烟气与空气的高效换热,实验研究了蓄放热时间对高温温度场均匀性的影响, 探讨了蓄热周期对烟气和空气进出口温度特性的影响,利用燃烧产物实现了四氟化炭高温分解。 相似文献
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J.J. Borrás-Almenar E. Coronado R. Georges A.V. Palii B.S. Tsukerblat 《Physics letters. A》1996,220(6):342-350
A general solution of the exchange-transfer problem is given for an arbitrary nuclearity mixed valence cluster with one delocalized electron over identical high-spin cores. The matrix elements of the second order exchange-transfer operator are expressed in terms of the products of 6j-symbols only and do not contain high-order recoupling coefficients. All pathways of exchange-transfer through the intermediate non-Hund states are taken into account. The interplay between the double exchange, exchange-transfer and Heisenberg exchange is considered in detail for the simplest case of a symmetric d2-d1-d1 system. As distinguished from the double exchange and Heisenberg exchange the exchange-transfer is shown to stabilize the intermediate spin state of the d2-d1-d1 system. The influence of the exchange-transfer on the excess electron localization pattern is briefly discussed. The exchange-transfer is shown to affect unfavourably the condition of the delocalization over two sites. 相似文献
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Ç. B. Ãðÿçíîáa O. T. Huκumuè Ã. B. Öu÷uøáuëu К. A. БeжаПϐuиu 《Isotopes in environmental and health studies》2013,49(6):226-227
Anhand der Äquivalenz zwischen der Kaliummenge und der entsprechenden Zählrate (40K) werden Beziehungen angegeben, die es ermöglichen, die Kaliummenge zu bestimmen, deren radiometrischer Einfluβ bei verschiedenen Gesamieffektivitäten vernachlässigbar ist. Für die häufigsten Fälle von Gesamtaktivitätsmessungen von Spaltproduktgemischen mit Hilfe der β-Strahlung sind die radiometrisch vernachlässigbaren Kaliummengen für einige Nahrungsmittel angeührt. 相似文献
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C.J. BeechamS. Boag C.D. FrostT.J. McKetterick J.R. StewartK.H. Andersen P.M. BentleyD. Jullien 《Physica B: Condensed Matter》2011,406(12):2429-2432
Here we report on the development of polarization analysis (PA) techniques to be employed at the ISIS pulsed neutron source second target station. Both spin exchange optical pumping and metastability exchange optical pumping techniques are being developed at ISIS to produce polarized neutron spin filters for use as neutron polarizers and analysers. We focus on the developments of a polarization solution on the LET spectrometer, including the updated design of the PASTIS XYZ coil set and single crystal silicon analyser cell. We also report on the construction of a combined polarizer/analyser solution for the WISH diffractometer. 相似文献
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G. Suciu J. C. Toussaint J. Voiron 《Journal of magnetism and magnetic materials》2002,240(1-3):229-231
We have studied the interlayer exchange coupling between Gd and Co through Pt and Cr spacers in a series of multilayers. Magnetization curves have been analyzed with a model, taking into account bilinear and biquadratic interlayer exchange couplings between Gd and Co. The interlayer exchange coupling constants have been determined as a function of the Pt or Cr spacer layer thickness. 相似文献