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Spin Injection, Accumulation, and Relaxation in Metals
Published in Evgeny Y. Tsymbal, Žutić Igor, Spintronics Handbook: Spin Transport and Magnetism, Second Edition, 2019
There are many topics that relate to the effects of carrier spin on transport in electronic systems. Among the most fundamental, spin-dependent tunneling (SDT) [1] (see also Chapter 11, Volume 1) has the longest history and offers a technique for measuring the spin polarization of electric current in a ferromagnet. Magnetic tunnel junctions (MTJs) [2–4] form a device family with the largest magnetoresistance ratio (MR) and with the highest promise for application (see also Chapter 12, Volume 3). Giant magnetoresistance (GMR) [5, 6] (see also Chapter 4, Volume 1) provides a descriptive understanding of spin-dependent scattering in ferromagnets and in thin-film ferromagnet/nonmagnetic (F/N) metal multilayers. The spin injection phenomenology [7] has a history that is second to SDT. Developed for the study of F/N metal interfacial spin transport and the study of spin-relaxation processes, spin injection introduced a number of ideas and techniques that have been commonly adopted. Researchers today invoke fundamental concepts such as spin injection, spin accumulation, spin-polarized currents in ferromagnet/nonmagnet structures, and pure spin currents. All these concepts were described, defined, and demonstrated in a series of experimental and theoretical papers in the mid-1980s [7–10].
Polymer Nanocomposites as Nanoadsorbents for Environment Remediation
Published in Chaudhery Mustansar Hussain, Ajay Kumar Mishra, Nanocomposites for Pollution Control, 2018
Priyanka Ghanghas, Kavita Poonia, Dinesh Kumar
Magnetoresistance (MR) is a process in which the resistance of a material changes when an external magnetic field is applied. Giant magnetoresistance (GMR) is the large resistance change that occurs when the relative orientation of the magnetic domains in adjacent layers is adjusted from anti-parallel to parallel under an applied magnetic field. It is defined as the ratio (ft’AP-ft’Pj/ft’P, where RP and RAP are the resistances of materials for parallel and antiparallel alignments, respectively. The GMR aspect was first discovered in multilayered structural materials, in which ferromagnetic Fe metal layers were separated by a nonmagnetic Cr layer in 1988. This is intriguing, in particular, for conducting polymer-based multifunctional nanocomposites, as the conducting polymer is a conjugated structure with electrons being exchanged and transported along the backbone in the case of oxidative remediation of heavy metal species.
Magnetic Nanoparticle-Based Biosensing
Published in Nguyễn T. K. Thanh, Clinical Applications of Magnetic Nanoparticles, 2018
Kai Wu, Diqing Su, Yinglong Feng, Jian-Ping Wang
GMR sensor. After the discovery of the giant magnetoresistance effect in 1988, the GMR sensor has been well developed and successfully used in hard disk drive heads since late 1990s. GMR sensors, also known as spin-valves, have demonstrated the advantage of their high sensitivity to satisfy the challenge of increasing data densities as well as data rates. Almost at the same time, in 1998, researchers in the Naval Research Laboratory first demonstrated the use of GMR sensors as biosensors to detect bindings in bimolecular level, such as bindings between antigen–antibody, DNA–DNA, etc. They also demonstrated the systematic view for such biosensors. Magnetic particles are used as tags to infer the number of captured analytes, and the Wheatstone bridge is incorporated in the biosensing system to readout and amplify the electrical signal. Researchers kept most of these features later in their research.
Ab initio study of pressure dependence of the structural, elastic and thermodynamic properties of AlXY3 (X = B, C)
Published in Phase Transitions, 2023
Missoum Radjai, Abdelmadjid Bouhemadou, Saad Bin-Omran
The ternary aluminum boride and carbide materials AlXY3, where X = B or C, which belong to the interesting family of intermetallic boride and carbide materials, have been the subject of relatively few theoretical and experimental studies [9–11]. These materials have useful uses such as giant magnetoresistance [7]. Note that the incorporation of aluminum in the carbides of transition metals opens the way to an improvement of their low resistance to oxidation and their intrinsic fragility which limit their applications in various fields [10]. Ghule et al. [9] synthesized AlCY3 by arc melting and subsequent annealing, determined its crystalline structure through Rietveld analysis of the powder x-ray diffraction (XRD) data and explored its electronic band structure and density of states through first-principles calculations. It emerges from their study that AlCY3 crystalizes in a cubic perovskite structure and has a metallic character with a coexistence of covalent, ionic and metallic bonds. Hao and co-workers [10] performed first-principles calculations to investigate the elastic and electronic properties of AlCY3. Recently, Ghule et al. [11] reported a theoretical study of the electronic properties of AlCY3 and AlBY3. It emerges from this study that both AlBY3 and AlCY3 have a metallic character.
Spin-resolved transport properties of atomic carbon chain between sawtooth zigzag-edge graphene nanoribbons electrodes
Published in Molecular Physics, 2021
Haiqing Wan, Xianbo Xiao, Guanghui Zhou, Wei Hu
In the present work, using the first-principles method, we investigate the magnetic transport in C-STGNRs systems. The proposed molecular device can realise the unusual dual spin-filtering effect with the perfect spin filtering efficiency up to 100, high-performance dual spin diode effect with the rectification ratio up to about and obvious NDR behaviour with the peak-to-valley ratio up to about . Moreover, we have observed a giant magnetoresistance (MR) with the MR ratio approaching in this device model. The analysis of the evolution of transmission coefficients and electrode band structures indicate that the perfect dual spin filter and spin diode effect are due to a dual selection rule: symmetry match for the band structure of the electrodes and the eigenstates of the carbon chains, i.e. simultaneous presence of open conductance channels on the chain atoms and in the two STGNR(5, 3) electrodes making the electronic band-to-band tunnelling available. However, the NDR behaviours originate from the bias-induced molecular orbital movement and decreasing overlap for both spin band between two STGNR electrodes.
Efficient autonomous material search method combining ab initio calculations, autoencoder, and multi-objective Bayesian optimization
Published in Science and Technology of Advanced Materials: Methods, 2022
Yuma Iwasaki, Hwang Jaekyun, Yuya Sakuraba, Masato Kotsugi, Yasuhiko Igarashi
Heusler alloys are an important application of the autonomous material search systems. They have attracted much attention in recent years because they exhibit various physical properties [16–19]. One of the most attractive physical properties is half-metallicity, which has one metallic spin band and one semiconducting spin band [20]. They have been extensively studied for applications in tunnel magnetoresistance [21–24], giant magnetoresistance [25–28], and other spintronics devices [29–31]. However, since the material search space is extremely vast due to their multi-elemental nature and their disordered phases, the development of Heusler alloys is very difficult.