共查询到19条相似文献,搜索用时 62 毫秒
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我们制备了氧化物材料科La0.65Ca0.35Mn1-xFexO3(x=0,0.01,0.02,0.03),研究了材料在低场0.57T下的磁电阻效应,我们发现氧化物材料La0.65Ca0.35Mn1-xFexO3据里温度Tc及电阻峰位温度Tp均值铁含量的增加而下降,这主要是因为Fe离子不参加双交换作用,且阻挡了双交换作用的进行,材料的铁磁作用随铁含量增加而减弱。利用迪尼模型计算了La0.65Ca0.35Mn1-xFexO3材料在零场及磁场为0.57T下电阻随温度的变化关系,理论计算结果与实验数据吻合得较好。 相似文献
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20世纪自旋电子学的高速发展以及对强关联电子材料的进一步研究使得具有庞磁电阻效应的稀土掺杂锰氧化物成为凝聚态物理和功能材料研究的重要领域。锰氧化物的载流子自旋极化率高,在居里度附近有很大的磁电阻效应,因此在自旋电子学中有潜在应用前景。锰氧化物是典型的强关联电子材料,它对目前有关强关联体系的认识提出了很大挑战。本文介绍了锰氧化物所具有的包括庞磁电阻效应在内的各种效应及其可能的应用。 相似文献
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NiFe/Co/Cu/Co结构自旋阀GMR效应及Co夹层的影响研究 总被引:2,自引:0,他引:2
用射频磁控溅射发射法成功制备了NiFe/Cu/Co自旋阀多层膜材料,改变Cu层的厚度,研究材料的GMR效应与Cu层厚度的关系,结果表明Cu为2.5nm时样品的MR值最大,其磁电阻效应MR可达1.6%,在NiFe和Cu之间插入一Co薄夹层,通过对不同温度厚度Co夹层的样品的MR曲线及磁滞回线的研究,讨论了Co夹层对样品磁电阻的影响并分析了原因,结果表明插入适当的Co层将提高材料的磁电阻效应,可达2. 相似文献
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巨磁电阻效应的发现开拓了磁电子学的新领域,20世纪90年代,磁电子学到了迅速的发展,并在实际应用方面取得了显著的经济效益与巨大的社会效益,本世纪初,研究重点已转移到新的半导体自旋电子学方向,并取得了重要进展。本文结合作者率领的科研组的研究工作,阐述了从磁电子学材料到半导体自旋电子学材料的发展概况,其中,重点介绍了稀磁半导体材料的研究进展。 相似文献
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张世远 《中国材料科技与设备》2006,3(5):62-65,70
本文重点介绍了掺Ag的钙钛矿锰氧化物和磁铁矿的磁电阻增强效应。结构分析表明,这些材料是由铁磁性的钙钛矿锰氧化物相或亚铁磁性的磁铁矿相与非磁性的金属Ag相所组成的两相复合物。由于金属Ag相的存在,它们的低场磁电阻效应明显增强。这可归因于传导电子在磁性相和非磁性相界面处的自旋相关散射的增强。 相似文献
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钙钛矿型复合氧化物催化剂中过渡金属离子的状态及其间的相互作用 总被引:3,自引:0,他引:3
讨论了B位二元复下钛矿型复合氧化物LaMyM'1-yO3(M,M'=Mn,Fe,Co;y=0.0 ̄1.0)中过渡金属离子的状态及其间的相互作用。在Mn-Co复合体系中,富锰区(y〉0.5)Mn^3+-O^2--Mn^4+的铁磁超交换作用对样品的磁性起决定作用。富钴区(y〉0.5)Co^2+和Co^III离子的存在及其浓度是影响磁性和电导性的主要因素。y=0.5时样品的结构决定了样品的强铁磁性质。在 相似文献
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Jiaqi Ran Linchuan Wang Mingsu Si Xiaolei Liang Daqiang Gao 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(10):2206367
Promoting the initially deficient but economical catalysts to high-performing competitors is important for developing superior catalysts. Unlike traditional nano-morphology construction methods, this work focuses on intrinsic catalytic activity enhancement via heteroatom doping strategies to induce lattice distortion and optimize spin-dependent orbital interaction to alter charge transfer between catalysts and reactants. Experimentally, a series of different concentrations of fluorine-doped lanthanum cobaltate (Fx-LaCoO3) exhibiting excellent electrocatalytic activity is synthesized, including a low overpotential of 390 mV at j = 10 mA cm−2 for OER and a large half-wave potential of 0.68 V for ORR. Meanwhile, the assembled rechargeable Zn–air batteries deliver an excellent performance with a large specific capacity of 811 mAh/gZn under 10 mA cm−2 and stability of charge/recharge (120 h). Theoretically, taking advantage of density functional theory calculations, it is found that the prominent OER/ORR performance arises from the spin state transition of Co3+ (Low spin state (LS, t2g6eg0) → Intermediate spin state (IS, t2g5eg1) and the mediated d-band center upshift by F atom incorporation. This work establishes a novel avenue for designing superior electrocatalysts in perovskite-based oxides by regulating spin states. 相似文献
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A. M. Goldman P. I. Kraus K. Nikolaev V. Vas''ko A. Bhattacharya W. Cooley 《Journal of Superconductivity》2001,14(2):283-290
Advances in thin film deposition techniques, in particular molecular beam epitaxy, have made it possible to produce bilayer heterostructures of high-temperature superconductors and manganite perovskites. The latter exhibit the phenomenon of colossal magnetoresistance (CMR). The half-metallic character of CMR compounds results in their carriers being spin polarized. The geometry of the structures that have been fabricated is such that it is possible to measure the interface conductance–voltage characteristic G(V) as well as the current–voltage characteristic of the superconducting half of the bilayer. Injection of carriers suppresses superconductivity in the latter, with a current gain of order unity. The data exhibit qualitative features of equilibrium theories of spin-polarized transport across an interface between a ferromagnet and an anisotropic superconductor, although a detailed understanding requires generalization of the theory to include out of equilibrium effects. 相似文献
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Osami Yanagisawa Mitsuru Izumi Wei-Zhi Hu Kenji Nakanishi Hideo Nojima 《Journal of Superconductivity》1999,12(1):307-310
The magnetic behavior of the distorted perovskite manganese, Pr0.65Ca0.35MnO3 was studied by X-band electron spin resonance for powder samples. We observed the onset of the charge-ordered state at T
CO215 K, the antiferromagnetic transition with the peak of the ESR linewidth, H
p–p
at T
AF180 K and the canted antiferromagnetic transition at T
CAF125 K associated with the abrupt increase of both the effective magnetization and H
p–p
. Below 90 K, the absorption intensity profile becomes weakened with decreasing temperature suggesting the existence of some kind of magnetic disorder below 90 K, which is responsible for a part of evidence of the existence of the spin-glass state as has been proposed by Yoshizawa et al., Phys. Rev. B
52, 1689 (1996). 相似文献
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采用沉淀法合成了不同钴锰含量的碳纳米管(CNTs)/钴锰氧化物纳米复合材料. 利用XRD、SEM、TEM、BET和FT-IR等方法对材料进行了表征, 考察了不同复合材料对锂空气电池放电及充电过程的影响, 同时对循环性能进行了研究. 结果表明: 钴锰比例为4:0与0:4时, 产物为CNTs/Co3O4与CNTs/Mn3O4, 钴锰比例为3:1、2:2、1:3时, 产物为CNTs/(Co, Mn)(Co, Mn)2O4。产物具有良好的分散性能, 氧化物负载在碳管表面, 其中CNTs/Mn3O4的分散性能最好。随着锰含量的增加, 电池的放电性能提高, CNTs/Mn3O4的放电电压达到2.92 V。随着钴含量的增加, 电池的充电性能提高, 充电电压最低为3.80 V。钴锰比为3:1时的产物充放电过电势(△V)仅为1.05 V, 5次循环后依然保持着良好的放电性能。 相似文献
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Cheng Zhang Shuaishuai Ding Yuan Tian Jing Wang Yunzhong Chen Tongyun Zhao Fengxia Hu Wenping Hu Baogen Shen 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(40):2303375
Tailoring the interface between organic semiconductor (OSC) and ferromagnetic (FM) electrodes, that is, the spinterface, offers a promising way to manipulate and optimize the magnetoresistance (MR) ratio of the organic spin valve (OSV) devices. However, the non-destructive in situ regulation method of spinterface is seldom reported, limiting its theoretical research and further application in organic spintronics. (La2/3Pr1/3)5/8Ca3/8MnO3 (LPCMO), a recently developed FM material, exhibits a strong electronic phase separation (EPS) property, and can be employed as an effective in situ spinterface adjuster. Herein, we fabricated a LPCMO-based polymer spin valve with a vertical configuration of LPCMO/poly(3-hexylthiophene-2,5-diyl) (P3HT)/Co, and emphasized the important role of LPCMO/P3HT spinterface in MR regulation. A unique competitive spin-scattering mechanism generated by the EPS characteristics of LPCMO inside the polymer spin valve was discovered by abstracting the anomalous non-monotonic MR value as a function of pre-set magnetic field (Bpre) and temperature (T). Particularly, a record-high MR ratio of 93% was achieved in polymer spin valves under optimal conditions. These findings highlight the importance of interdisciplinary research between organic spintronics and EPS oxides and offer a novel scenario for multi-level storage via spinterface manipulation. 相似文献
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Magnetocaloric and colossal magnetoresistance effects of the layered perovskite La1:4Sr1:6Mn2O7 compound have been studied. A broad peak of magnetic entropy change (-ΔSM) is found above the Curie temperature (TC=120 K), which can be associated with the existence of two-dimensional short range ferromagnetic order. Additionally, the curvilinear shape of -ΔSM for layered perovskite is quite different from that of the Ln1-xAxMnO3 probably arising from magnetocrystalline anisotropy. At the same time, a wide peak of colossal magnetoresitance effect near TC is found in the layered provskite La1:4Sr1:6Mn2O7. 相似文献
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La—Na—Mn—O纳米颗粒的磁卡效应 总被引:11,自引:0,他引:11
用溶胶-凝胶法制备了La1-xNaxMnOz多晶纳米颗粒。用结构分析,程序升温还原及磁性测量等方法研究限样品的结构和磁卡效应。结果表明,样品的居里温度TCn-O键长有密切的联系,这些材料在低磁场下在室温附近较大的温度范围内具有相当大的磁熵变,是较为理想的室温磁致冷工作物质。 相似文献