磁流体热透镜耦合光磁效应用于高电压电流的光学测量

本文报道将一种新的光学效应，即磁流体热透镜耦合光磁效应〔１〕，应用于高电压电流测量的初步结果。该方法最大的特点是不用偏振光，避免了易受干扰的保偏装置，提高了信噪比，同时又具有光纤传输的优点，并使得该系统简单、经济；和国际上惯用的法拉第效应相比有可能推动电流（磁场）光学测量实用化的进程。结果表明实验系统可以优于１％的精度测量０～５００Ａ范围的电流。

光磁效应研究的新进展

光磁效应研究始于六十年代末 ,它是磁光效应的一种逆效应。近年来光磁效应研究取得了相当明显的进展 ,本文分 ( 1 )光磁各向异性和光磁效应的可逆特性 ,( 2 )光磁电流和光磁电阻 ,( 3)

基于磁流体热透镜耦合光磁效应测量高压电流方法的研究

通过实验和理论分析,提出了将磁流体热透镜耦合光磁效应应用于高压电流测量的新方法,并设计了一套测量系统.该方法最大的特点是不用偏振光,避免了复杂的保偏装置,使得该系统简单、经济,同时又具有光纤传输的优点.

两种双核稀土配合物的光致变色和光磁效应

利用光诱导电子转移机理和配位驱动组装策略探索室温光磁效应材料的合成.通过组装稀土硝酸盐与1,10-菲罗啉(phen)获得2种同构双核稀土配合物[Ln_(2)(NO_(3))_(6)(phen)_(2)](1:Ln=Gd;2:Ln=Dy).由于具有电子给体-受体结构特征,目标产物在光照后发生电子转移,电子由硝酸根的氧原子转移到phen的氮原子,进而产生光生自由基并发生肉眼可见的颜色变化.除光致变色外,配合物1和2在室温下具有光磁效应.本研究为构筑室温光致变色和光磁效应杂化材料提供了一种通用方法:配位组装顺磁金属盐与菲罗啉衍生物.

光致变色材料研究取得新进展

光致变色物质具有颜色和多种物理性质可逆变化的特征，其中磁性随光刺激发生变化（即所谓光磁效应）的化合物除具有一般光致变色物质的强光防护、光开关等功能外，还可能和磁共振成像、光信息存储等方面发挥重要作用。

福建物构所光致变色材料研究取得新进展

光致变色物质具有颜色和多种物理性质可逆变化的特征,其中磁性随光刺激发生变化（即所谓光磁效应）的化合物除具有一般光致变色物质的强光防护、光开关等功能外,还可能在磁共振成像、光信息存储等方面发挥重要作用。多氰基配位化合物被认为是最有发展前景的此类材料,多年来备受关注,但是,其光磁效应通常在液氮温度以下发生,而罕见于室温附近。

光致变色材料研究取得新进展

中国科学院福建物质结构研究所结构化学国家重点实验室首次发现了3d-4f多氰基配位化合物的光致变色现象和室温光磁效应,发展出一类具有室温光磁效应的光诱导价态互变化合物。

交换作用对CeF_3晶体磁性和磁光效应的影响

研究了顺磁性晶体CeF3内交换作用有效场随温度的变化关系,给出了其形式为Hin=(-0·68-0·002T)×10-6M.结合该关系,用量子理论的计算得到了与实验值吻合较好的磁化率倒数、Verdet常数倒数随温度的变化关系,并且用光磁效应的概念和规律对结果作了进一步分析,指出光诱导促进了该晶体内电子间的交换作用.

Energy Spectra of a Magnetic Quantum Ring with an Off-Center Impurity

In this paper, we calculate the low-lying spectra of a single-electron magnetic quantum ring with an offcenter Coulomb impurity, where the magnetic field is zero within the ring and constant elsewhere. The impurity, either an acceptor or a donor, is located at a distance d as measured from the plane of the ring along the vertical z direction. The magnetic moments are found in order to get visible discontinuities at the points of the ground-state orbital angular momentum L transitions induced by magnetic fields.

LIGHT MODULATION COMBINING POCKELS EFFECT WITH FARADAY EFFECT AND ITS FUNCTIONS

With brief statements of the linear electro-optical modulation and magnetooptical modulation, using the method of resultant of optical amplitude vectors and the methed of Jones matrix, formulas for intensity of transmitted light through the optical analyzer of various composition of electro-optical effect with magneto-optical effect are derived. The results show that the output beam from the analyzer carries information on current (or magnetic field), voltage (or electric field), active power and apparent power. When the light beam transmitted through the analyzer are transformed into electric signals, three kinds of information are included: the DC term corresponding to an active power, the term with frequency ω(50 Hz) corresponding to current or voltage, and the term with frequency 2ω(100 Hz) corresponding to an apparnt power.So, we can use the electric filter circuit to pick out the DC component for measuring active power; to pick out the component with frequency ω(50 Hz) for measuring current or voltage; and to pick out the component with frequency 2ω(100 Hz) for measuring apparent power. The paper discusses what quantities are measured when the analyzer is set on certain definite values, and ponts out the optimum selection for various measurements.

锗中少數載流子壽命測量方法的比較

引言我們在进行锗中少数载流子~*寿命的测量工作中,共采用了四种測量方法:“光电导衰退法”“双脉冲法”“曼納电桥法”“光磁效应法”。这些测量寿命的基本方法,不但适用于锗,也适用于其它半导体材料。利用光电导衰法”“双脉冲法”可以测量硅中少子的寿命。用“光磁效应”可以测量小于0.1微秒的短寿命。

科技期刊亮点

器件老化处理影响有机发光磁效应 西南大学物理科学与技术学院熊祖洪等研究了器件老化处理对有机发光磁效应的影响。相关研究成果发表在5月4日出版的《科学通报》杂志上。

Study of magneto-optical effects in γ-Fe_2O_3/ZnFe_2O_4 nanoparticle ferrofluids, using circularly polarized light

When circularly polarized light travels through a ferrofluid film in the presence of an applied magnetic field, the transmitted light will behave as elliptically polarized light, because of magnetic birefringence and dichroism. The angular distribution of the relative intensity of the transmitted light can be obtained using a polarizer, so that the ratio of both the long and short ax- es-as well as the orientation angle of the ellipse, corresponding to the direction of the applied magnetic field--can be deter- mined, and whether the ferrofluids samples are stable during the measurement can be directly judged from the shape of the distribution curves. Thus, the ratio of the amplitudes Ax/Ay and the added phase difference A r can be resolved in the elliptically polarized light, and information on both the magnetic birefringence An and the dichroism Ak can be deduced for the ferrofluid sample. From the orientation angles of both right-handed and left-handed elliptically polarized transmitted light, the direction of the applied magnetic field can be accurately determined. Using circularly polarized light, the magnetic birefringence and dichroism of pure γ-Fe2O3 ferrofluids and γ--Fe2O3/ZnFe2O4 binary ferrofluids were studied. For the binary ferrofluids, a mod- ulating effect on the magnetic birefringence and dichroism was revealed.

Solvent-and metal-directed lanthanide-organic frameworks based on pamoic acid:observation of slow magnetization relaxation,magnetocaloric effect and luminescent sensing

Two types of lanthanide coordination polymers, namely, [Ln（PA）（NO3）（DMA）3]n （Ln=Gd （1）, Dy （2）, Eu （3）, Tb （4）） （type I）, and {[Ln2（PA）3（DMF）4]＇2DMF} （Ln=Eu （5）, Tb （6）） （type II） （PA=Pamoic acid, DMA=dimethylacetamide, DMF=N,N-dimethylformamide）, have been synthesized by the reaction of Ln（NO3）a-6H20 with pamoic acid through layer diffusion method. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy （IR）, thermogravimetric analysis （TGA）, fluorescence and magnetic measurements. Solvents and lanthanide atoms in the reaction play an important role in controlling different structures. Type I demonstrated 1-D linear chain structure connected by Ln atoms and PA ligands. Type II exhibited non-interpenetrating 3-D 6-connected 43612 nets based on binuclear [Ln2（CO2）6（DMF）4] cores. Magnetic properties of complexes 1-4 were investigated in details. Complex 1 shows significant magnetocaloric effect with -△Sm=20.37 J kg^-1 K^-1 at 3.0 K and 7 T. Complex 2 exhibits slow relaxation of the magnetization. Complexes 3-6 exhibit both ligand- and metal-centered fluorescent properties. Complex 6 demonstrates fluorescent sensing of DMF and Cu^2＋ ion.

Study of doping effect,phase separation and heterojunction in CMR manganites

Mixed-valence manganites have attracted considerable research focus in recent years not only because of the potential application of colossal magnetoresistance(CMR) in magnetic devices,but also because of many intriguing physical properties observed in these materials.Doping elements at A-site can alter the filling of 3d Mn band and the tolerance factor.Therefore the hole-and electron-doped CMR manganites exhibit a rich phase diagram.In addition,more theoretical and experimental results suggest that phase separation is a critical factor for the understanding of CMR phenomena.Recently,there is an increasing interest in the fabrication and investigation on manganite-based heterojunction,which demonstrated excellent rectifying property,large MR,and photovoltaic effect.

Vector imaging of electric field-induced reversible magnetization reversal in exchange-biased multiferroic heterostructures

Exchange bias between ferromagnetic and antiferromagnetic layers has been widely utilized in spintronic devices.Controlling the exchange bias in magnetic multilayers by an electric field(E-field)has been proposed as a low-power solution for manipulating the macroscopic properties such as exchange bias fields and magnetization values,while how the magnetic domains respond to the E-fields has rarely been reported in an exchange-biased system.Here,we realize the vector imaging of reversible electrical modulation of magnetization reversal in exchange-biased CoFeB/IrMn/PMN-PT(011)multiferroic heterostructures,utilizing in-situ quantitative magneto-optical Kerr effect(MOKE)microscopy.Under the electrical control,magnetic domains at-80 Oe rotate reversibly between around 160°and 80°-120°,whose transverse components reverse from 225°to 45°correspondingly.Moreover,pixel-by-pixel comparisons are conducted to further imply the reversible magnetization reversal by E-fields.Efield-induced reversible magnetization reversal is also demonstrated without applying external magnetic fields.Vector imaging of electrical manipulation of exchange bias is of great significance in understanding the magnetoelectric effect and the development of next-generation spintronic devices.

Distributed parametric modeling and simulation of light polarization states using magneto-optical sensing based on the Faraday effect

To solve the problems encountered in practical processes of magneto-optical sensing, the infinitesimal distributed-parameter model and finite-element accumulation of different dielectric properties of micromaterials were used to describe the evolution of light polarization states, instead of the previously commonly used method of lumped-parameter simulation, thus essentially explaining the mechanism of sensing, magneto-optical effects, and related factors, and achieving multiphysics coupling using the COMSOL finite-element analysis method. Considering the cases of the Faraday effect without and with line birefringence, the magneto-optical effect and output characteristics of an infinitesimal magneto-optical sensor were simulated and studied. The results verified the effectiveness of the infinitesimal sensor model. Because the magnetic field, stress, and temperature changes alter the dielectric properties of magneto-optical materials, the finite-element accumulation method lays a good foundation for research on theoretical analysis and performance of magneto-optical sensors affected by factors such as the magnetic field, temperature, and stress.

Ultrasensitive iron-based magnetic resonance contrast agent constructed with natural polyphenol tannic acid for tumor theranostics

Because of the toxicity of Gd(Ⅲ)complexes and the poor T1 magnetic resonance imaging(MRI)contrast of superparamagnetic iron oxide,the development of new stable,non-toxic,and efficient contrast agents is desirable.Herein,tannic acid(TA),a large natural polyphenol,and bovine serum albumin(BSA)were used to construct non-toxic Fe(Ⅲ)complexes with increased relaxivity based on a strategy slowing the molecular spin.Compared with the commercial T1 contrast agent Magnevist■,TA-Fe@BSA not only exhibits comparable T1 MRI contrast enhancement under 0.5,1 and 7 T magnetic fields both in vitro and in vivo,but also has better stability and biocompatibility.Moreover,TA-Fe@BSA with near-infrared(NIR)absorption demonstrates efficient tumor ablation via photothermal effects.These results demonstrate their strong potential as an alternative T1 MRI contrast agent and tumor theranostics agent in clinical settings.