Thermal spin molecular logic gates modulated by an electric field

Logic gates are fundamental structural components in all modern digital electronic devices. Here, nonequilibrium Green's functions are incorporated with the density functional theory to verify the thermal spin transport features of the single-molecule spintronic devices constructed by a single molecule in series or parallel connected with graphene nanoribbons electrodes. Our calculations demonstrate that the electric field can manipulate the spin-polarized current. Then, a complete set of thermal spin molecular logic gates are proposed, including AND, OR, and NOT gates. The mentioned logic gates enable different designs of complex thermal spin molecular logic functions and facilitate the electric field control of thermal spin molecular devices.

Quasiprobability Distribution of Squeezed Thermal Spin States in Ferromagnet

We study squeezed properties of magnon squeezed thermal spin states by using the distribution of Q function in the ferromagnet. It is found that the distribution of Q function strongly depends on the temperature T and coupling parameter γ. Below the transition temperature Tc, the distribution Q function in the squeezed thermal spin state presents a richer structure than in the normal state. Non-classical effects have been observed. In the transition from the normal to the squeezed thermal spin state, the phase symmetry of the magnon system is spontaneously broken.

Analyzing Thermal Stratification and Nanoparticle Shapes Influence on an EMHD Ternary Nanofluid Flow amidst Two Spinning Disks

The present study examines the thermal distribution of ternary nanofluid flow amid two spinning disks influenced by electric and magnetic fields. Keeping in view the shape of the particles, the electrically conducting ternary nanofluid is analyzed with variable thermophysical features. Three types of nanoparticles namely Copper, Aluminum Oxide, and Graphene with spherical, cylindrical, and platelet shapes are taken respectively and are immersed in a (50-50)% ratio of water and ethylene glycol mixture which acts as a base fluid. The anticipated problem is addressed by employing a reliable and user-friendly numerical bvp4c built-in collocation scheme. This solution is then showcased through illustrations and tables. Strengthening the radiation results in an enhanced heat transfer rate. Radial and azimuthal velocities once rotation of disks is enhanced. The key findings provide a strong theoretical background in photovoltaic cells, solar collectors, radiators, solar water heaters, and many other applications.

Thermal Spin Squeezing as a Signature of Thermal Global Entanglement in Heisenberg Models

We study thermal spin squeezing (TSS) and thermal global entanglement (TGE) in a general Heisenberg spin chain, in the presence of Dzyaloshinskii-Moriya interaction and an external magnetic field. We derive an inequality associating the squeezing parameter and the global concurrence, which establishes (TSS) as a signature of (TGE). The inequality reduces to equality for particular symmetric chains which also associates TSS with bipartite entanglement in such systems. We also check the results by presenting two numerical examples.

Thermal entanglement in molecular spin rings

The thermal entanglement in the triangular molecular spin ring with Dzyaloshinskii-Moriya interaction is studied. The concurrences of arbitrary two spins of the triangular molecular spin ring for various cases are evaluated. The tendency of the concurrence with Dzyaloshinskii-Moriya interaction and temperature is analysed and discussed. We note that the concurrence arrives at its maximum in the regime with the large Dzyaloshinskii-Moriya interaction and low temperature, and gradually decreases to zero with the increase of temperature. The concurrence has different features for the ferromagnetic and antiferromagnetic cases. For completeness, we also numerically calculate the concurrence of spin rings with N 〉 3 spins and analyse their behaviours.

Teleportation and thermal entanglement in two-qubit Heisenberg X Y Z spin chain with the Dzyaloshinski-Moriya interaction and the inhomogeneous magnetic field

This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski-Moriya interaction. It shows that for a fixed Dz, the increase of bz will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski-Moriya interaction for the average fidelity of teleportation to be optimal.

Effect of thermal deformation on giant magnetoresistance of flexible spin valves grown on polyvinylidene fluoride membranes

We fabricated flexible spin valves on polyvinylidene fluoride（PVDF） membranes and investigated the influence of thermal deformation of substrates on the giant magnetoresistance（GMR） behaviors. The large magnetostrictive Fe_（81）Ga_（19）（Fe Ga） alloy and the low magnetostrictive Fe_（19）Ni_（81）（Fe Ni） alloy were selected as the free and pinned ferromagnetic layers.In addition, the exchange bias（EB） of the pinned layer was set along the different thermal deformation axes α_（31） or α_（32） of PVDF. The GMR ratio of the reference spin valves grown on Si intrinsically increases with lowering temperature due to an enhancement of spontaneous magnetization. For flexible spin valves, when decreasing temperature, the anisotropic thermal deformation of PVDF produces a uniaxial anisotropy along the α_（32） direction, which changes the distribution of magnetic domains. As a result, the GMR ratio at low temperature for spin valves with EB α_（32）becomes close to that on Si, but for spin valves with EB α_（31）is far away from that on Si. This thermal effect on GMR behaviors is more significant when using magnetostrictive Fe Ga as the free layer.

Thermal entanglement in two-qutrit spin-1 anisotropic Heisenberg model with inhomogeneous magnetic field

The thermal entanglement of a two-qutrit spin-1 anisotropic Heisenberg XXZ chain in an inhomogeneous magnetic field is studied in detail. The effects of the external magnetic field （B）, a parameter b which controls the inhomogeneity of B, and the bilinear interaction parameters Jx = Jy ≠ Jz on the thermal variation of the negativity are studied in detail. It is found that negativity N decreases when the values of magnetic field, inhomogeneity b and temperature are increasing. In addition, N remains at higher temperatures for higher values of Jz and lower values of B and b.

Photon-mediated spin-polarized current in a quantum dot under thermal bias

Spin-polarized current generated by thermal bias across a system composed of a quantum dot （QD） connected to metallic leads is studied in the presence of magnetic and photon fields. The current of a certain spin orientation vanishes when the dot level is aligned to the lead＇s chemical potential, resulting in a 100% spin-polarized current. The spin-resolved current also changes its sign at the two sides of the zero points. By tuning the system＇s parameters, spin-up and spin-down currents with equal strength may flow in opposite directions, which induces a pure spin current without the accompany of charge current. With the help of the thermal bias, both the strength and the direction of the spin-polarized current can be manipulated by tuning either the frequency or the intensity of the photon field, which is beyond the reach of the usual electric bias voltage.

A Thermal Analogue of the Zel’Dovich Effect

We analyze in this work anisotropic heat conduction induced by a harmonically oscillating laser source incident on rotating conductors, exploiting an analogy with an effect discovered long ago, called the Zel’dovich effect. We re-covered the main results of a recently published paper that predicts the translational Doppler frequency shift of a thermal wave induced on a sample moving with uniform rectilinear motion. We extend then this framework to take into account the frequency shift of a thermal field propagating on a rotating platform. We show that it coincides with the rotational frequency shift which has been recently observed on surface acoustic waves and hydrodynamic surface waves, called rotational superradiance. Finally, we use an analogy with the Tolman effect to deduce a simple estimate of the average temperature gradient induced by rotation, showing the existence of a new cooling effect associated with heat torque transfer.

Study on the Model of Thermal Channel Spinning Process for PET Polymer

A mathematical model to describe the TCS process inPET high-speed melt-spinning is established.The de-velopment of crystallinity,molecular orientation andmorphological features of high-speed-spun PET fiberin TCS process is investigated at take-up speeds rangingfrom 3600-4400 m/min and thermal channel tempera-tures ranging from 160-200℃ by simulation.The pro-files of tensile force,running velocity,temperature,bi-refringence,crystallinity and diameter in the TCS spin-line for various process conditions are obtained.Thepredicted results using this model are compared with themeasured crystallinty,diameter and birefringence.Theresults indicate that they are in fairly good agreement.The"necking point"in the TCS spinline can be predictedby this model,and its position changes with the corre-sponding process parameters such as take-up speed andthermal channel temperature.It is found that the neck-ing point moves towards the spinneret when the take-upspeed or the thermal channel temperature increases.

海森堡XYZ自旋链系统的热纠缠与局域量子不确定性研究

研究了热平衡温度,自旋交换相互作用,Dzyaloshinskii-Moriya(DM)相互作用及外加非一致性磁场对两比特海森堡XYZ自旋链量子系统的热纠缠与局域量子不确定度的影响,对比分析了并发度量子纠缠与局域量子不确定度描述自旋链系统量子关联的差别.结果表明自旋链系统的量子纠缠在热平衡温度,DM相互作用及外加磁场的非一致性参数的变化情况下均会出现纠缠突然死亡的再生现象,而自旋链系统的局域量子不确定度随着这些参数呈连续变化现象.并且,自旋交换相互作用,DM相互作用及外加横向磁场作用强度较小时,他们的变化对自旋链系统的量子纠缠与局域量子不确定度的影响有着明显的差别.

聚乙二醇@聚乙烯醇同轴相变纤维的储热特性

以具有高相变焓的聚乙二醇(PEG 4000)为核层相变材料(PCM)、聚乙烯醇(PVA)为壳层支撑材料、绿色溶剂水为壳层和核层材料溶剂,通过同轴静电纺丝制备出不同核层纺丝液浓度、进液速度的核-壳相变纤维。扫描电镜和透射电镜照片显示,在PEG质量分数为45%、进液速度为0.06 mL/h时,PEG@PVA具有良好的形貌及较高含量的PEG,相变纤维核壳分界面明显。红外光谱分析显示,PEG与PVA化学相容性良好;差示扫描量热分析和热重分析表明,PEG@PVA熔融温度为62.8℃,熔融焓为86.40 J/g,封装效率为42.2%,并且相变纤维膜起始热分解温度较高,在经过500次热循环实验后,熔融焓约损失3.1%,仍能保持绝大部分相变能力;导热测试表明,PEG@PVA膜的热导率介于壳层PVA与核层PEG之间;模拟PEG@PVA膜在工作环境中的温度变化得到温度-时间曲线,结果表明,相变纤维膜可以有效地调节微环境的温度。

热效应在电流驱动反铁磁/铁磁交换偏置场翻转中的显著作用

电流驱动的面内交换偏置场翻转具有无需外磁场辅助、抗磁场干扰以及强磁各向异性等优势,受到广泛关注.然而,在纳米级厚度薄膜系统中,反铁磁/铁磁异质结的阻塞温度较低,同时电流脉冲会产生大量的焦耳热,理论上电流热效应对于交换偏置场翻转有着显著作用,但是其作用机制缺乏相关研究和验证.我们制备了一系列反铁磁IrMn厚度不同的Pt/IrMn/Py异质结,系统性地研究了热效应在电流翻转交换偏置场中的作用机制.结果表明,在毫秒级电流脉冲下,焦耳热能够使得器件升温至阻塞温度以上,解除反铁磁/铁磁界面的交换耦合,同时电流产生的奥斯特场和自旋轨道矩能够翻转铁磁磁矩,在降温过程中完成交换偏置场的翻转.并且,在翻转过程中,反铁磁/铁磁异质结的各向异性磁阻曲线呈现与温度相关的两步磁化翻转现象,分析表明该现象起源于交换偏置耦合与铁磁直接交换作用之间的竞争关系.本文的研究结果厘清了热效应在电流驱动交换偏置场翻转过程中的重要作用,有助于推动基于电控交换偏置场的自旋电子器件发展.

聚甲醛制备及其可纺性研究

通过聚甲醛制备及其可纺性能研究,系统分析了聚甲醛中共聚单体(DOL)、催化剂(CA)添加量,产品熔融指数(MFR)对聚甲醛纺丝性能的影响。研究结果表明,适当提高聚甲醛中DOL、降低CA含量和提高产品MFR有助于改善聚甲醛的纺丝性能,其中DOL和CA添加比例分别为3%~6%和2~3 ppm,MFR控制在8.8~19.8 g/10 min时聚甲醛的纺丝性能最佳,制备的聚甲醛纤维拉伸强度可达6.6 g/d。通过对不同纺丝性能的聚甲醛样品进行熔融指数、结晶性能、球晶形态和热稳定性能测试分析,明确了聚甲醛熔融指数、结晶度和热稳定性能是影响聚甲醛纺丝性能的关键技术指标,球晶形态是次要技术指标。

聚对苯二甲酰对苯二胺气凝胶纤维的制备与性能

气凝胶纤维具有良好的柔韧性,其织物在可穿戴保温隔热领域受到了人们高度的关注。聚对苯二甲酰对苯二胺(PPTA)具有优异的耐热性、耐化学品腐蚀等性能,是制备气凝胶纤维的理想材料。然而,目前利用PPTA纤维(对位芳纶)的纳米纤维分散液制备气凝胶纤维的过程复杂、耗时且成本高,因此本工作通过合成具有良好可加工性的PPTA溶液,利用湿法纺丝和冷冻干燥工艺制备PPTA气凝胶纤维,极大地简化了工艺流程。实验分析表明,通过改变PPTA溶液的浓度可以有效地控制气凝胶纤维的孔结构及机械强度。当PPTA溶液的质量分数为2%时,制得的气凝胶纤维的孔隙率高达94.5%,断裂强度可达7.8 MPa;除此之外,该气凝胶纤维还具有高的比表面积(291 m2/g)和低的热导率,其织物的热导率为29.65 mW/(m·K)。当PPTA溶液的质量分数为5%时,气凝胶纤维的断裂强度高达20.5 MPa。本工作中所制备的气凝胶纤维具有极高的孔隙率、超低的密度和热导率以及良好的力学性能,为新一代保温隔热纺织品的设计和制造开辟了新的途径。

光热转换纳米纤维膜制备与性能研究

光热转换纳米纤维膜在产业用纺织品等领域中应用广泛。文中利用静电纺丝技术制备聚偏氟乙烯(PVDF)纳米纤维膜,通过在纺丝液中掺杂硫化铋颗粒(Bi_(2)S_(3))和氧化石墨烯颗粒(GO)或纤维膜浸泡盐酸多巴胺的方式对PVDF纳米纤维膜进行改性,得到不同组分纳米纤维膜材料。从形貌、机械性能、热稳定性能、光热转换性能和耐腐蚀性能等方面进行评价,其中PDA-GO-Bi_(2)S_(3)-PVDF纳米纤维膜纤维形貌良好、直径分布均匀、力学性能优良,具有良好的光热转换性能,光热转换温度可达101℃,是未改性PVDF纳米纤维膜的两倍,同时具有良好的热稳定性和耐腐蚀性能。

熔纺双组分超细纤维成型工艺及其应用研究进展

熔纺双组分超细纤维由于其原料和成型技术的组合多样性而备受青睐。然而,在现有的制备工艺中,熔纺双组分超细纤维存在如能耗大、难以细旦化和污染环境等问题,限制了其在实际生产和高质应用领域的进一步发展。并且在实际的生产过程中,不同的原料选择、组件使用及工艺调控等因素都对熔纺双组分超细纤维成型效果影响显著。因此,合理调控熔纺双组分超细纤维成型过程中各阶段影响因素对其综合性能进一步提升具有重大意义。为更全面理解熔纺双组分超细纤维的本质,本文以桔瓣型纤维和海岛型纤维为研究基体,探究了熔纺双组分超细纤维的纺丝成型机理及其影响因素;阐述了熔纺双组分超细纤维多样的开纤工艺(机械开纤、化学开纤和热能开纤);归结了熔纺双组分超细纤维在合成革、空气过滤和医疗卫生等材料领域的应用;最后对熔纺双组分超细纤维广阔的发展前景进行了展望。

基于工程化设备通过调控纺丝温度提高中间相沥青炭纤维力学和导热性能

基于工程化设备,在恒定挤出量条件下,通过调控纺丝温度制备了中间相沥青炭纤维(MPCFs),探究纺丝温度对MPCFs微观结构、力学和导热性能的影响。结果表明:随着纺丝温度由309升高至320℃,MPCFs的微观结构由石墨片层细小的褶皱劈裂辐射状结构逐步向石墨片层粗大的劈裂辐射状结构转变,拉伸强度由2.16增大到3.23 GPa,热导率由704升高到1078 W·m^(−1)·K^(−1)。这主要是因为纺丝温度越高,沥青熔体黏度越小,喷丝口处挤出胀大效应越弱,沥青熔体在喷丝孔流道内形成的微晶取向得以保持,以此制备的炭纤维具有更大的晶体尺寸和更高的微晶取向。

针织用聚乳酸纤维可纺性研究及性能分析

文章旨在比较市面上两种不同聚乳酸切片的可纺性差异,研究分析熔融纺丝前后切片与长丝性能的差异与影响因素。对聚乳酸低弹丝的微观形态、拉伸性能与取向度以及聚乳酸切片的分子量分布、热稳定性能、流变性能进行测试表征。结果表明:由1#切片制得的聚乳酸纤维截面较为致密紧实,具有更高的断裂伸长率、断裂强度、取向度以及结晶度,同时断裂伸长率与断裂强度的CV值较小,产品稳定性高,适合批量生产;纺丝温度较低时,1#切片可纺性更好,2#切片需要设置更高的纺丝温度来提高熔体的可纺性;2#切片的热稳定性能弱于1#切片,纺丝温度大于1#切片,造成热分解程度远大于1#切片,影响产品的机械性能。