Ultrafast Dynamics of BiFeO3 Thin Films Studied by Dual-Color Femtosecond Spectroscopy

The ultrafast dynamics in (100)-oriented BiFeO₃ thin films were studied from 20 K to 300 K by using the dual-color femtosecond pump-probe spectroscopy, which were performed by the 400 nm (3.1 eV) pump pulses above the energy gap of 2.67 eV and the 800 nm (1.55 eV) probe pulses below the energy gap of 2.67 eV. From the temperature-dependent transient reflectivity changes (??R/R), the anomalous changes were clearly observed below 200 K caused by magnons. Thus, the femtosecond pump-probe spectroscopy could unambiguously reveal the magnetization dynamics in BiFeO₃ with strong magnetoelectric coupling.     

Si(111)衬底上六方YMnO3薄膜的制备与铁电性质

采用化学溶液法在Si(111)衬底上制备了YMnO3薄膜.XRD结果表明,所制备的薄膜为六方纯相YMnO3,且具有部分择优取向生长.以Pt为顶电极,测试了YMnO3薄膜的电滞回线,结果表明,所制备的YMnO3薄膜具有良好的铁电性质.     

Electronic,Magnetic, Electric and Magnetocaloric Properties of the Multiferroic Orthorhombic YMnO3

Journal of Superconductivity and Novel Magnetism - Multiferroic oxide materials have attracted much intention in recent years due to their application in different fields such as magnetic...     

添加AlN对FePt薄膜结构和磁性的影响

采用射频磁控溅射制备了FePt(50nm)和[FePt(2,3,5nm)/AlN(1nm)]n膜,之后在550℃退火30min,研究了周期数(n)和AlN含量对[FePt/AlN]_n系列多层膜结构及磁性的影响.结果表明,多层膜的矫顽力和矩形比均在n=8时出现较大值;周期数的增大会引起晶粒尺寸的长大;AlN的加入不但可以抑制FePt粒子的长大,使晶粒体积(V_grain)和磁激活体积(V*)趋于一致,而且还能有效地降低晶粒间交换耦合作用,并且AlN含量越大,晶粒间交换耦合作用的程度越弱.     

Electronic Properties of C60 Thin Films

Abstract

The electronic structure of polycrystalline C₆₀ thin films has been investigated using surface photovoltage spectroscopy (SPS) and conductivity measurements. the films show n-type semiconductivity with an activation energy of ～ 0.8 eV as found from the temperature dependence of the conductivity at high temperatures. the electronic structure emerging from our SPS results comprises a 1.6 eV photo-conduction gap, a mobility gap of about 2.25 eV and two gap states, a donor and an acceptor, at 0.35 eV and (1.0-1.1) eV, respectively, below the photo-conduction edge. the results indicate the possibility of the existence of band tails, extending into the optical gap of these films, as well as other deep gap states.     

Electronic Properties of C60 Thin Films

The electronic structure of polycrystalline C₆₀ thin films has been investigated using surface photovoltage spectroscopy (SPS) and conductivity measurements. the films show n-type semiconductivity with an activation energy of ∼ 0.8 eV as found from the temperature dependence of the conductivity at high temperatures. the electronic structure emerging from our SPS results comprises a 1.6 eV photo-conduction gap, a mobility gap of about 2.25 eV and two gap states, a donor and an acceptor, at 0.35 eV and (1.0-1.1) eV, respectively, below the photo-conduction edge. the results indicate the possibility of the existence of band tails, extending into the optical gap of these films, as well as other deep gap states.     

Structure and Magnetic Properties of La0.66Sr0.33MnO3 Thin Films Derived Using Sol-Gel Technique

In this paper the results of a study of the structural and magnetic properties of La_0.66Sr_0.33MnO₃ (LSMO) polycrystalline films grown on glass substrate using Sol-Gel technique are presented. The samples were structurally characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The average grain size range of 30 nm has been obtained from XRD investigations of granular LSMO samples. Zero Field Cooling (ZFC) and Field Cooling (FC) magnetization measurements have been performed and magnetic hysteresis loops of LSMO were recorded at various temperatures. The temperature dependences of the magnetization of LSMO films recorded in ZFC and FC regimes exhibited considerable difference between the curves. The blocking and the ferromagnetic phase transition temperatures of about 262?K and 300?K, respectively, were observed from magnetization measurements.     

磁控溅射MoO3半导体功能薄膜的制备与结构性能研究

采用射频磁控溅射技术分别在Si(100)和玻璃衬底上通过调整不同的溅射功率和退火温度成功制备了MoO3薄膜.利用X射线衍射、扫描电镜、紫外可见光分光光度计、接触角测量等进行了表征和分析.X射线衍射表明400℃以上沉积的MoO3结晶薄膜属正交晶系,沿(0k0)(k=2n)取向择优生长,衍射峰强度和薄膜的结晶度随溅射功率的提高逐渐增强;利用扫描电镜观察表面形貌,发现结晶的薄膜表面发生了不同程度的变化,由初期均匀分布的纳米细长状颗粒长大成二维片状结构;紫外可见光分光光度计测试表明,薄膜在可见光区具有良好的光学透过性,平均透过率达60％以上;接触角测量发现薄膜呈明显亲水性,通过后续的表面氟化改性热处理     

铁电PLZT薄膜的钙钛矿型结构与性能的研究

讨论了用射频磁控溅射沉积的ＰＬＺＴ（７．５／６５／３５）陶瓷薄膜的结构和铁电性能。研究表明，在不加热的Ｐｔ／Ｔｉ／Ｓｉ衬底上沉积ＰＬＺＴ薄膜即钙钛矿型的高度取向薄膜，没有绿石相出现，同时具有很好的微观结构；增加薄膜的厚度导致ａ轴取向的增长；火处理有助于ＰＬＺＴ薄膜的钙钛矿相的增长并在薄膜中出现了蔷薇状共晶组织。这种ＰＬＺＴ薄膜的剩余极化强度、矫顽场强度分别为２２．９μ／ｃｍ＾２和６２．４ＫＶ／ｃｍ     

NiFeNb薄膜的磁特性及磁阻效应研究

研究了射频磁控溅射膜（Ｎｉ８１Ｆｅ１９）１００－Ｎｂｘ的各向异性磁阻效应ＡＭＲ、矫顽力Ｈｃ、饱和磁化强度４ｘｍｓ和饱和磁化场Ｈ。研究其作为磁阻磁头材料和低磁场高灵敏度材料的可能性。我们发现Ｎｂ的含量对（Ｎｉ８１Ｆｅ１９）１００－ｘＮｂｘ的各向异性磁阻效应ＡＭＲ＝２％、矫顽力Ｈｃ＝１１９Ａ／ｍ和饱和磁化场Ｈｘ＝４４５Ａ／ｍ，适宜于低磁场高灵敏度检测材料。     

残余应力对SrRuO3薄膜磁学及电输运性能的影响

采用射频磁控溅射法在单晶SrTiO₃ (STO)衬底和硅(Si)衬底上制备出不同取向的SrRuO₃ (SRO)薄膜, 对薄膜的残余应力进行了分析, 并研究了应力对不同取向SRO薄膜磁学性能与电输运特性的影响。根据X射线衍射(XRD)结果分析可知, Si基SRO薄膜为多晶单轴取向薄膜, 且应力来源主要为热失配拉应力; STO基SRO薄膜为外延薄膜, 其应力主要为热失配压应力和外延压应力; 磁学性能测试表明, (001)取向SRO薄膜比(110)取向薄膜拥有更高的居里温度T_C; 压应力提高了(001)取向SRO薄膜的T_C, 却降低了(110)取向薄膜的T_C。电阻性能测试表明, 对于在同种类型衬底上沉积的SRO薄膜, (001)取向的薄膜的剩余表面电阻比(RRR)高于(110)取向的薄膜。另外, 拉应力引起了薄膜微结构的无序度增加, 弱化了表面电阻率的温度依赖性, 提高了金属绝缘体转变温度(T_MI)。     

热处理对WO3薄膜的结构和气致变色性能的影响

用溶胶－凝胶法在普通钠钙玻璃上制备了WO3薄膜，并分别在250℃，360℃，450℃的空气环境中对薄膜进行了热处理，用SEM，XRD观察了薄膜的表面形貌，分析了薄膜的微观结构及热处理温度和催化剂含量对薄膜的结构和气致变色性能的影响。     

Effects of Magnetic Annealing on Structure and Magnetic Properties of L10-FePt/Ag Films

The structural and magnetic properties of L1₀-FePt/Ag films were studied by X-ray diffraction and a vibrating sample magnetometer. The FeAg/Pt films were obtained by depositing FeAg thin films on thermally oxidized Si (001) substrates via magnetron sputtering and Pt layers on their surface after annealing FeAg thin films at 400 °C with and without an out-of-plane magnetic field of 10 kOe. These films were further annealed at various temperatures to obtain L1₀-FePt phase. The results indicated that the pre-annealing of FeAg thin films under 10 kOe magnetic field caused (001) orientation of Fe particles, and the deposition of Pt layer on such orientated underlayers reduced the ordering temperature of FePt in FeAg/Pt films, realizing the L1₀-FePt phase at 400 °C. The higher coercivity and ordering degree were also observed in the samples, compared with those pre-annealed without magnetic field at the same annealing condition.     

软磁性薄膜微波磁特性的研究进展

概述了软磁性单层膜、多层膜、颗粒膜的微波磁特性研究进展,对这些薄膜的基本磁性和微波磁性进行了总结和讨论,得出软磁纳米晶薄膜可望成为应用于微波领域的主体候选材料,指出了Co(Fe)基软磁性薄膜微波特性的研究方向.     

Structure and Ferroelectric Properties of Thin Heteroepitaxial NaNbO3 Films Obtained by RF Cathode Sputtering

Technical Physics Letters - Thin films of sodium niobate (NaNbO3) on a MgO(001) substrate with a predeposited SrRuO3 layer were obtained for the first time by the method of RF cathode sputtering in...     

较薄坡莫合金薄膜的磁性能和结构

基于辉光放电原理在不同的溅射气压下制备的NiFe薄膜,发现较低溅射气压下比较高溅射气压下制备的NiFe薄膜的磁性能要好得多.较低溅射气压下制备的NiFe(12nm)薄膜,各向异性磁电阻(AMR)值达到1.2%,而其矫顽力却只有127.4A/m.结构分析表明较低溅射气压下制备的NiFe薄膜结构缺陷较少,内应力小;而较高溅射气压下制备的NiFe薄膜结构缺陷较多,内应力大.     

Magnetic Properties of Nanometer-Scale NiZnCu Ferrite Thin Films Fabricated by Spray-Spin-Heating-Coating Method

A new nanometer-scale ferrite thin film with excellent high-frequency characteristics has been developed by the spray-spin-heating-coating method. The effects of the ion synthesis mechanism, chemical stoichiometry, fabrication method, and doping content on the magnetic properties and microstructure of the thin films have been analyzed. The films formed between 75℃ and 90℃ by spray-spin-heating-coating methods was discovered with fine grain size of about 21 nm, high saturation magnetization (4πMs) of about 6.5 kGs, coercivity of about 9.8 Oe, as well as initial permeability of about 14.0. These films can be widely used in radio-frequency integrated circuit devices.     

Sb掺杂ZnTe薄膜结构及其光电性能

采用真空蒸发工艺在玻璃衬底上制备了ZnTe和掺Sb-ZnTe多晶薄膜,并在氮气气氛中对薄膜进行热处理.分别利用XRD、SEM、紫外-可见分光光度计、霍尔效应测试仪对薄膜的晶体结构、表面形貌、元素组成以及光学、电学性能进行表征,研究Sb掺杂量和热处理对薄膜性能的影响.结果表明:未掺杂薄膜为沿(111)晶面择优生长的立方相闪锌矿结构,导电类型为P型.Sb掺杂并未改变ZnTe薄膜晶体结构和导电类型,但衍射峰强度降低;Sb含量直接影响着Sb在ZnTe中的存在形式,掺Sb后抑制了薄膜中Te和Zn的结合,使薄膜中Te的含量增加;室温下薄膜的光学透过率和光学带隙取决于掺Sb浓度和退火温度,并且掺Sb后ZnTe薄膜的载流子浓度显著增加,导电能力明显增强.