氧化物反铁磁Cr2O3薄膜的研究进展

氧化物反铁磁Cr2O3薄膜在自旋电子学器件中有着广泛的应用.重点论述了反铁磁Cr2O3的早期基础性研究,以及反铁磁Cr2O3薄膜在交换偏置和磁电效应方面的研究进展.最后指出了氧化物反铁磁Cr2O3薄膜研究中存在的部分问题,并展望了它的发展前景.     

铁电-铁磁复合材料的研究现状及发展趋势

铁电—铁磁复合材料是一种由铁电相和铁磁相复合而成，具有磁电转换功能的新材料，它兵有广阔的应用前景。系统地介绍了铁电—铁域复合材料的原理、性质及研究进展，最后对存在的问题及发展趋势作了分析。     

磁性材料交换偏置效应研究进展

磁性材料中交换偏置效应对自旋电子学的基础研究和应用发展起到了至关重要的作用,因此也成为无机非金属材料的研究中最为活跃的领域之一.由于交换偏置效应来源于铁磁/反铁磁界面处的交换耦合作用,所以相关的研究工作主要集中在铁磁/反铁磁双层膜体系;在一些基态为反铁磁的类钙钛矿锰氧化物中,由于存在相分离形成的铁磁团簇也观察到了交换偏置现象;此外,很多磁性材料纳米化后也出现了交换偏置效应.主要从这3方面介绍了在新材料体系中交换偏置效应的研究进展,以及交换偏置效应在自旋相关器件中的应用,提出了一些研究中面临的挑战并对发展方向作出展望.     

LTCC用介电/铁磁复合材料的研究进展

在介绍介电/铁磁复合材料在LTCC应用前景的基础上,阐述了作为LTCC器件材料的介电相材料和铁磁相材料所必须具备的特性.综述了常见的LTCC介电/铁磁复合材料体系和复合工艺.指出了研究中存在的问题以及今后主要研究方向——寻找新的复合体系.并指出介电/铁磁复合材料也可以应用在吸波材料上.     

铁磁型减振钢的性能特征和应用前景

介绍了铁磁型减振钢的减振性能和使用条件的关系;阐述了铁磁型减振钢的力学性能特征;分析了在撞击、摩擦、振动条件下铁磁型减振钢的应用前景和应注意的问题。     

修正的Heisenberg模型：铁磁与反铁磁自旋波理论

应用修正的Ｈｅｉｓｅｎｂｅｒｇ模型研究铁磁与反铁磁系统低激发态的自旋波，修正了旧的理论结果。     

铁基阻尼材料的发展现状和趋势

铁基阻尼材料是一种具有广阔应用前景的结构-功能一体材料,它具有优良的阻尼性能、综合力学性能和冷热加工性能。本文全面地介绍了铁磁型、孪晶型和复相型三类铁基阻尼材料的阻尼机制、研究和应用现状,并对铁基阻尼材料的发展趋势进行了展望。     

NiO/CoFe双层膜的交换机制研究

通过改变制备NiO薄膜的氩气压和衬底材料,研究了NiO的结构、表面粗糙度对NiO/CoFe双层膜交换耦合场Hex的影响.实验表明完全自旋未补偿面与交换耦合场的产生没有直接联系,但交换耦合场Hex与界面状况密切相关.增大NiO的表面粗糙度会使交换耦合场Hex减小.应用随机场理论在考虑了实际界面存在的粗造度、杂质和缺陷等实际情况下,正确地预测了交换耦合场的数量级,而且对交换耦合场与铁磁层厚度tFM、反铁磁层厚度tAFM以及交换耦合场的温度特性等实验结果做出了合理解释.并应用随机场模型对反铁磁/铁磁双层膜中铁磁层矫顽力Hc与铁磁层厚度tFM的关系进行了定量计算,发现矫顽力Hc与铁磁层厚度1/tFM成正比,这一结果表明理论计算与我们的实验数据符合得很好.     

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。     

氮化铁磁流体的制备

对以气相液相反应法制备氮化铁磁流体进行了探索,并摸索到制备氮化铁磁流体的工艺流程,所研制的氮化铁磁流体磁饱和强度达到0.05T(脓缩前),并将其应用在静态密封上,成功地研制出磁流体密封安全阀.     

Preparation of ferromagnetic carbon electrode from charcoal blocks

A ferromagnetic carbon electrode, if it really exists, will have an interesting role in the electrochemistry because it attracts the paramagnetic species such as free radicals or ion radicals and still it may keep the stabilities that carbon has. Since ferromagnetic carbon has been prepared in a powdery form, to extend that technique for the preparation of a solid block of ferromagnetic carbon, have been expected in the present work. A wood charcoal piece was selected as the skelton of the ferromagnetic electrode. An aromatic hydrocarbon was adsorbed by the charcoal piece. Hydrogen reduction and vacuum heating was applied to this charcoal piece. Removing hydrogen atoms from both charcoal and the hydrocarbon were carried out in a CCl₄ atmosphere at 550°C. The results have shown that mechanically strong ferromagnetic carbon electrode can be obtained by the method described in this report.     

Electrically defined ferromagnetic nanodots

While ferromagnetic nanodots are being widely studied from fundamental as well as application points of views, so far all the dots have been physically defined; once made, one cannot change their dimension or size. We show that ferromagnetic nanodots can be electrically defined. To realize this, we utilize an electric field to modulate the in-plane distribution of carriers in a ferromagnetic semiconductor (Ga,Mn)As film with a meshed gate structure having a large number of nanoscaled windows.     

A Review on the Regulation of Magnetic Transitions and the Related Magnetocaloric Properties in Ni-Mn-Co-Sn Alloys

In Ni-Mn-X(X=In,Sn,Sb) ferromagnetic shape memory alloys,a ferromagnetic transition from paramagnetic to ferromagnetic austenite and a martensitic transformation from ferromagnetic austenite to weak magnetic martensite occur in some particular composition ranges,in which abundant physical properties have been observed by the abrupt change of magnetization and resistivity around their transition temperatures in these alloys.Therefore,tuning the martensitic transformation temperature(TM) and enlarging the workingtemperature interval for Ni-Mn-X(X=In,Sn,Sb) alloys,are of great importance.In the present paper,we will focus on the effect of external factors,including pre-deformation,annealing,and high pressure annealing,on the magnetic transitions and the related magnetocaloric properties in Ni-Mn-Co-Sn ferromagnetic shape memory alloys.Our approaches and the main results in this particular field will be reviewed.     

利用近饱和磁化产生的巴克豪森效应测量铁磁件二轴应力

讨论了一种检测铁磁材料的内部应力的无损检测新技术。利用该技术,以近饱和磁化产生的巴克豪森效应与应力的关系,测量了铁磁构件的二轴应力和焊接构件的残余应力。检测结果与传统的Ｘ射线检测法的结果相一致。该检测技术在工程检测中有广泛的适用性。     

Spin-polarized light-emitting diodes based on heterostructures with a GaAs/InGaAs/GaAs quantum well and ferromagnetic GaMnSb injection layer

Light-emitting diode structures with an InGaAs/GaAs quantum well and a ferromagnetic GaMnSb layer as a p-type semiconductor have been manufactured and investigated. A magnetic-field-induced circular polarization of electroluminescence in these structures has been obtained, the degree of which (0.012 at 0.37 T) is almost constant in the temperature interval of 10–50 K. Circular polarization is determined by the injection of spin-polarized holes from the ferromagnetic GaMnSb layer.     

Manipulation of spin currents in metallic systems

The transport properties of diffusive spin currents have been investigated in lateral ferromagnetic/non-magnetic metal hybrid structures. The spin diffusion processes were found to be strongly dependent on the magnitude of the spin resistances of connected materials. Efficient spin injection and detection are accomplished by optimizing the junction structures on the basis of the spin resistance circuitry. The magnetization switching of a nanoscale ferromagnetic particle and also room temperature spin Hall effect measurements were realized by using an efficient pure-spin-current injection.     

Ferromagnetism in two-dimensional black phosphorus induced by phthalocyanine cobalt

Two-dimensional (2D) magnets have been the recent research focus due to their potential to meet requirements of continuous miniaturization of spintronic devices. However, very few intrinsic 2D ferromagnetic materials, in particular room-temperature magnets, have been demonstrated because of spin fluctuations and disturbed superexchange caused by the dimensional reduction. Herein, a synchronous ultrasonic exfoliation and doping method is proposed to fabricate ferromagnetic 2D black phosphorus (BP) through the adsorption of phthalocyanine cobalt (CoPc). The electron transfer from BP to CoPc is confirmed by X-ray photoelectron spectroscopy, which is believed to be responsible for the ferromagnetic ground state in as-doped BP (Co-BP) with a saturation magnetization of 0.18 emu g^?1. The density functional theory calculations well-support the charge transfer and the origin of ferromagnetism in Co-BP. In addition, the electron transfer results in the restricted activity of lone pair electrons, which might improve the antioxidant capacity of BP. Our study shed light on room-temperature ferromagnetism in 2D materials.

     

磁性材料磁热效应的研究

设计组装了一种冰量热计法磁致热效应测量仪,它可用于测量交变场下铁磁样品磁致热的绝对量。从磁热测量的结果,得到了一些单一磁样品和磁－良导体复合样品的磁致热效应实验规律。     

Spin transport in a thin graphite flake

We have studied the spin transport on a 30-nm thick and several micrometer long oriented graphite flake using a spin-valve configuration with four ferromagnetic Co electrodes of different widths and several \upmum\upmu\hbox{m} separation. A 5-nm thin Pt layer has been introduced in between the ferromagnetic Co injector/detector and the graphite surface. In spite of the conductivity mismatch problem, efficient electrical spin injection and detection in graphite has been achieved. The magnetoresistance in the local and half-local electrodes shows clear maxima with symmetry around zero field. The spin transport can be detected up to 150 K.