ZnxFe3-xO4-α-Fe2O3 纳米多晶材料中的隧道磁电阻效应与微结构

在具有纳米绝缘层的多晶锌铁氧体体系中，当晶界为α－Fe2O3纳米量级的绝缘层时，则构成（ZnxFe3-xO4-α－Fe2O3非均匀体，电子显微分析证实了这种微结构。该体系在0．5T磁场、4．2K温度下，磁电阻效应可达1280％，300K下为158％。     

Silicon‐Based Current‐Controlled Reconfigurable Magnetoresistance Logic Combined with Non‐Volatile Memory

Silicon‐based complementary metal‐oxide‐semiconductor (CMOS) transistors have achieved great success. However, the traditional development pathway is approaching its fundamental limits. Magnetoelectronics logic, especially magnetic‐field‐based logic, shows promise for surpassing the development limits of CMOS logic and arouses profound attentions. Existing proposals of magnetic‐field‐based logic are based on exotic semiconductors and difficult for further technological implementation. Here, a kind of diode‐assisted geometry‐enhanced low‐magnetic‐field magnetoresistance (MR) mechanism is proposed. It couples p‐n junction's nonlinear transport characteristic and Lorentz force by geometry, and shows extremely large low‐magnetic‐field MR (>120% at 0.15 T). Further, it is applied to experimentally demonstrate current‐controlled reconfigurable magnetoresistance logic on the silicon platform at room temperature. This logic device could perform all four basic Boolean logic including AND, OR, NAND and NOR in one device. Combined with non‐volatile magnetic memory, this logic architecture with unique magnetoelectric properties has the advantages of current‐controlled reconfiguration, zero refresh consumption, instant‐on performance and would bridge the processor‐memory gap. Our findings would pave the way in silicon‐based magnetoelectronics and offer a route to make a new kind of microprocessor with potential of high performance.     

CMR锰氧化物在激光及光探测方面的应用进展

混合价态钙钛矿锰氧化物在外界温度变化和磁场作用下表现出巨大的磁电阻 (Colossalmagnetoresistance ,简称CMR)效应 ,引起了人们的广泛关注。由于CMR材料在传感器、探测器以及硬盘读出磁头等应用器件研发上极具潜力 ,科学家们对其进行了大量研究。本文在简单介绍CMR材料结构和机理的基础上 ,着重报道了我们利用CMR薄膜的激光感生热电电势 (LITV)制备激光功率 能量探测器和利用电阻在室温附近的巨大变化研制的光热辐射探测器 (Bolometer)方面的新进展     

Fe-ZnSe纳米复合颗粒膜的制备和磁电阻效应

采用射频溅射法制备了"纳米铁磁金属颗粒-半导体基体"Fe-ZnSe复合颗H粒膜,研究了颗粒膜的结构、磁性和磁电阻效应.实验结果表明,在室温下Fe-ZnSe复合颗粒膜中纳米Fe颗粒表现出超顺磁性,颗粒膜的磁电阻变化率△ρ/ρ0数值达到4.6%;颗粒膜的磁电阻变化率△ρ/ρ0随温度的变化关系表明△ρ/ρ0数值随温度的下降而增大.     

光照下巨磁电阻氧化物的室温响应性质

实验测量了巨磁电阻锰氧化物的光吸收谱,研究了在波长为０．６３μｍ的Ｈｅ－Ｎｅ激光和波段λ＝８￣１４μｍ的红外辐射条件下,薄膜在室温下的光响应性质。通过分析光响应与高制频率、偏置电流的关系,讨论了光响应机理。     

Researches on the computer digital control system of giant magnetostrictive actuator

In this paper, a computer digital control system of giant magnetostrictive actuator (GMA) was designed. In GMA system, driving magnetic field was provided by variable magnetic field generated by exciting coil current and offset magnetic field generated by permanent magnet. And Terfernol-D was used as the giant magnetostrictive materials (GMM). GMA’s control model was analysed and the whole control system was established. In the computer digital control system, the control core were single-chip microcomputer and PC with modularization thinking. And the control algorithm was PID. Design for system’s hardware and software was completed and software package was developed. Experiment shows that the GMA system is controlled automatically and monitored real-time. It lays a foundation of further improving control precision of GMA, improving the entire system’s dynamic characteristics and realizing automatic control.     

Photoinduced negative magnetoresistance in 6,13-bis(triisopropylsilylethynyl)-pentacene field-effect transistors

We report on photoinduced negative organic magnetoresistance in low external magnetic-fields (<100 mT) in 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-Pentacene) field-effect transistors. An external magnetic field does not influence the dark current of our device. In contrast, there is a significant increase in photocurrent when magnetic field is applied to the irradiated device, which leads to negative magnetoresistance. The magnetoresistance and photoresponse values are strongly correlated and both are influenced by applied voltages and irradiation intensity. We attribute the observed photoinduced negative magnetoresistance in TIPS-Pentacene field-effect transistors to the presence of electron-hole pairs under irradiation. The overall dissociation probability of electron-hole pairs rises under the influence of an external magnetic field, which leads to a higher number of free charge carriers.     

纳米Fe-In2O3颗粒膜的低温磁效应

采用射频溅射法制备了纳米Fe—In2O3颗粒膜，研究了颗粒膜在低温下的两种特殊磁效应——巨磁电阻效应和磁性弛豫效应。磁电阻测量结果表明，当Fe体积分数为35％时，颗粒膜样品的室温磁电阻变化率(△ρ/ρ0)为4．5％，而在温度T=2K时，∑ρ／ρ0达85％。根据颗粒膜低场磁化率-温度(x-T)关系证实，在一定温度下，颗粒膜中纳米Fe颗粒表现出磁性弛豫效应，当截止温度TB=50K时，颗粒膜的磁特性由超顺磁性转变为铁磁性；在截止温度以上，其饱和磁化强度与温度关系符合Bloch的T^3/2定律。     

Negative giant surface potential of vacuum-evaporated tris(7-propyl-8-hydroxyquinolinolato) aluminum(III) [Al(7-Prq)3] film

Negative giant surface potential was realized in a vacuum-evaporated film of tris(7-propyl-8-hydroxyquinolinolato) aluminum(III) [Al(7-Prq)₃]. Electroabsorption response of the film presented an inverted polarity to that of tris(8-hydroxyquinolinolato) aluminum (Alq₃), suggesting opposite noncentrosymmetry of molecular orientation. Asymmetric dice model with molecular geometric effect has been proposed, and propyl substitution at 7 position of the ligands was indicated to affects the molecular posture on the surface to invert the polarity of noncentrosymmetry. Our results opened a new possibility of controlling molecular orientation in a film for device applications.     

An Artificial Skyrmion Platform with Robust Tunability in Synthetic Antiferromagnetic Multilayers

Magnetic skyrmions are topologically nontrivial spin structures, and their existence in ferromagnetically coupled multilayers has been widely reported with a disordered arrangement. Here, a nucleation scenario of ordered skyrmions in nanostructured synthetic antiferromagnetic (SAF) multilayers is proposed and experimentally demonstrated using direct magnetization imaging, indirect magnetometer and magnetoresistance measurement, and micromagnetic simulation. Instead of relying on Dzyaloshinskii–Moriya interaction, the antiferromagnetic interlayer exchange coupling in the SAF multilayers fulfills the role of nucleation and stabilization of skyrmions. The robustness of the proposed skyrmion nucleation scenario is examined against temperature from 4.5 to 300 K and device size from 400 to 1200 nm. Interestingly, these synthetic skyrmions still behave well with a size less than 100 nm. The higher stability than generic magnetic domains can be attributed to topological protection. The results thus provide an artificial skyrmion platform to meet the functional needs of high density and designable arrangement in magnonic and spintronic applications.