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Spin filtering

Pu Duan, Klaus Schmidt-Rohr
A convenient one-dimensional magic-angle spinning NMR method is presented that provides selective NMR spectra of COH moieties in uniformly 13 C-enriched organic materials. This method, termed hydroxyl-proton selection (HOPS), eliminates the magnetization of protons directly bonded to carbons by recoupling the 1 H-13 C dipolar interaction for a short time (∼70 μs), which also serves as a chemical-shift filter to suppress 1 H magnetization of CH3 groups. After cross polarization to 13 C, the signals of COH and COOH carbons are observed selectively...
February 27, 2019: Journal of Magnetic Resonance
Manon Michel, Xiaojun Tan, Youjin Deng
We propose the clock Monte Carlo technique for sampling each successive chain step in constant time. It is built on a recently proposed factorized transition filter and its core features include its O(1) computational complexity and its generality. We elaborate how it leads to the clock factorized Metropolis (clock FMet) method, and discuss its application in other update schemes. By grouping interaction terms into boxes of tunable sizes, we further formulate a variant of the clock FMet algorithm, with the limiting case of a single box reducing to the standard Metropolis method...
January 2019: Physical Review. E
Mi-Mi Dong, Zi-Qun Wang, Guang-Ping Zhang, Chuan-Kui Wang, Xiao-Xiao Fu
Modulating the electronic and magnetic properties of phosphorene is important for fabricating multi-functional electronic and spintronic devices. Employing density functional theory combined with the non-equilibrium Green's function, we systematically investigate the electronic, magnetic and transport properties of hydrogenated armchair phosphorene nanoribbons chemically modified by 3d transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co and Ni). With chemical adsorption of transition metal atoms, the phosphorene nanoribbons exhibit excellent spin-polarized transport properties...
February 19, 2019: Physical Chemistry Chemical Physics: PCCP
Xifeng Yang, Fangxin Tan, Yaojun Dong, Hailin Yu, Yushen Liu
Based on the non-equilibrium Green function method combined with density functional theory, we investigate the spin-resolved transport through transition metal (TM) (= Cr, Mn, Fe and Ru)-containing molecular devices in the presence of zigzag graphene nanoribbon (ZGNR) electrodes. The wave-function mismatch for the single-spin component results in a perfect spin-filtering property near the Fermi level. Moreover, we also observe Fano and Breit-Wigner resonance peaks in the transmission spectrum. Under a temperature gradient, the single-spin electric current exhibits a remarkable negative differential thermoelectric resistance (NDTR) in the Ru-complex molecular device, which originates from the Fano asymmetry of the single-spin transmission peak near the Fermi level...
February 18, 2019: Physical Chemistry Chemical Physics: PCCP
Wen Zhang, Ping Kwan Johnny Wong, Xiaochao Zhou, Ashutosh Rath, Zhaocong Huang, Hongyu Wang, Simon A Morton, Jiaren Yuan, Lei Zhang, Rebekah Chua, Shengwei Zeng, Er Liu, Feng Xu, Ariando, Daniel H C Chua, Yuan Ping Feng, Gerrit van der Laan, Stephen J Pennycook, Ya Zhai, Andrew T S Wee
Ferromagnet/two-dimensional transition-metal dichalcogenide (FM/2D TMD) interfaces provide attractive opportunities to push magnetic information storage to the atomically thin limit. Existing work has focused on FMs contacted with mechanically exfoliated or chemically vapor-deposition-grown TMDs, where clean interfaces cannot be guaranteed. Here, we report a reliable way to achieve contamination-free interfaces between ferromagnetic CoFeB and molecular-beam epitaxial MoSe2 . We show a spin reorientation arising from the interface, leading to a perpendicular magnetic anisotropy (PMA), and reveal the CoFeB/2D MoSe2 interface allowing for the PMA development in a broader CoFeB thickness-range than common systems such as CoFeB/MgO...
February 18, 2019: ACS Nano
Yong-Chen Xiong, Shi-Jun Luo, Wang-Huai Zhou, Wei Li, Chuan-Kun Zhang
Metal-molecule-metal junction is considered the basing block and key element of molecular spintronic devices, within which to generate spin polarized currents is one of the most fundamental issues for quantum computation and quantum information. In this paper, by employing a parallel triple orbital molecule junction with large inter-orbital tunneling couplings, we propose theoretically a bidirectional spin filter where both spin-up and spin-down currents could be obtained by simply adjusting the external magnetic field to different regimes along a single direction, and the filtered efficiencies could reach almost 100%...
February 14, 2019: Journal of Chemical Physics
Xuming Wu, Lun Xiong, Yulin Feng, Cong Wang, Guoying Gao
Two-dimensional SnSe2 has become more and more attractive due to the excellent electronic, optoelectronic, and thermoelectric properties. However, the study on magnetic properties is rare. Inspired by the recent experimental synthesis of SnSe2 monolayer and Ag-doped SnSe2 thin films, we use the first-principles calculations combined with the nonequilibrium Green's function method to investigate the structural, electronic, magnetic, and spin transport properties of an Ag-doped SnSe2 monolayer. It is found that the doped system exhibits half-metallic ferromagnetism with the energy gap of about 0...
February 14, 2019: Journal of Chemical Physics
R Caruso, D Massarotti, G Campagnano, A Pal, H G Ahmad, P Lucignano, M Eschrig, M G Blamire, F Tafuri
The study of superconductor-ferromagnet interfaces has generated great interest in the last decades, leading to the observation of spin-aligned triplet supercurrents and 0-π transitions in Josephson junctions where two superconductors are separated by an itinerant ferromagnet. Recently, spin-filter Josephson junctions with ferromagnetic barriers have shown unique transport properties, when compared to standard metallic ferromagnetic junctions, due to the intrinsically nondissipative nature of the tunneling process...
February 1, 2019: Physical Review Letters
Sagar Mandava, Mahesh B Keerthivasan, Diego R Martin, Maria I Altbach, Ali Bilgin
PURPOSE: A new method for streak artifact reduction in radial MRI based on phased array filtering. THEORY: Radial imaging in applications that require large fields-of-view can be susceptible to streaking artifacts due to gradient nonlinearities. Coil removal methods prune the coils contributing the most to streaking artifacts at the expense of signal loss. Phased array beamforming is a form of spatial filtering used to suppress unwanted signals. The proposed method uses interference covariance generated from the streaking artifact samples which are manually extracted with phased array beamforming to suppress streaking in the images...
February 12, 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
J Tornos, F Gallego, S Valencia, Y H Liu, V Rouco, V Lauter, R Abrudan, C Luo, H Ryll, Q Wang, D Hernandez-Martin, G Orfila, M Cabero, F Cuellar, D Arias, F J Mompean, M Garcia-Hernandez, F Radu, T R Charlton, A Rivera-Calzada, Z Sefrioui, S G E Te Velthuis, C Leon, J Santamaria
The electronic reconstruction occurring at oxide interfaces may be the source of interesting device concepts for future oxide electronics. Among oxide devices, multiferroic tunnel junctions are being actively investigated as they offer the possibility to modulate the junction current by independently controlling the switching of the magnetization of the electrodes and of the ferroelectric polarization of the barrier. In this Letter, we show that the spin reconstruction at the interfaces of a La_{0.7}Sr_{0.3}MnO_{3}/BaTiO_{3}/La_{0...
January 25, 2019: Physical Review Letters
Chang-Jiang Zhang, Xue-You Huang, Ming-Chao Fang
NeighShrink is an efficient image denoising algorithm for the reduction of additive white Gaussian noise. However, it does not perform well in terms of Rician noise removal for MRI (Magnetic Resonance Imaging). Allowing for the characteristics of squared-magnitude MR (Magnetic Resonance) images, which follow a non-central chi-square distribution, the CURE (Chi-Square Unbiased Risk Estimation) is used to determine an optimal threshold for NeighShrink. Therefore, we propose the NeighShrinkCURE denoising algorithm...
January 31, 2019: Artificial Intelligence in Medicine
Daniel Nürenberg, Helmut Zacharias
The chirality-induced spin selectivity (CISS) in layers of helical molecules has gained considerable attention in the emerging field of spintronics, because the effect enables spin-filter devices under ambient conditions. Several theoretical studies have been carried out to explain this effect on a microscopic scale, but the origin of the effect is still controversial. In particular, the role of spin-flip scattering during electron transport is an open issue. In this study, we describe the electron and spin transport by macroscopic rate equations including spin-dependent losses and spin-flip scattering...
February 1, 2019: Physical Chemistry Chemical Physics: PCCP
Luis Ismael Asmat Lopez, Sebastian Ujevic Tonino, Michel Mendoza
In this work we study some applications for the pseudo-spin filters. The filters are potential barriers with hyperboloid sub-band contributions that are locally applied over the graphene nano-ribbons. These filters modulate the pseudo-spin and the quirality of the wave-function allowing the recovery of the conductance loss due to imperfections, bends, or constrictions (asymmetries) found in the system. The recovery of the conductance is fulfilled by a direct manipulation of the pseudo-spin polarization at both sides of the device by localizing the filters at the system's entrance and exit points...
January 23, 2019: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Ming-Yang Liu, Qing-Yuan Chen, Chao Cao, Yao He
Bismuth based (Bi-based) materials exhibit promising potential for the study of two-dimensional (2D) topological insulators or quantum spin Hall (QSH) insulators due to their intrinsic strong spin-orbit coupling (SOC). Herein, we theoretically propose a new inversion-asymmetry topological phase with tunable Rashba effect in a 2D bismuthene monolayer, which is driven by the sublattices half-oxidation (SHO). The nontrivial topology is identified by the SHO induced p-p band inversion at the Γ point, the Z2 topological number, and the metallic edge states...
January 23, 2019: Physical Chemistry Chemical Physics: PCCP
Jin Li, Maoyun Di, Zhi Yang, Li-Chun Xu, Yongzhen Yang, Xuguang Liu
In the present study, by cutting 6,6,12-graphyne along vertical and horizontal directions, two kinds of 6,6,12-graphyne nanodots (6,6,12-GYNDs) with different sizes are obtained. Using these 6,6,12-GYNDs, we theoretically designed two kinds of 6,6,12-graphyne-based molecular magnetic tunnel junctions (MMTJs) and investigated their spin-dependent transport properties. Depending on the orientation of the 6,6,12-GYNDs and the connection of the 6,6,12-GYNDs to electrodes, our results show that the two MMTJs have novel transport behaviors...
January 21, 2019: Physical Chemistry Chemical Physics: PCCP
Julien Ognard, Jawad Mesrar, Younes Benhoumich, Laurent Misery, Valerie Burdin, Douraied Ben Salem
INTRODUCTION: Previous studies have demonstrated the feasibility to explore moisturization with quantification imaging based on T2 mapping. The aim of this study was to describe and validate the first robust automated method to segment the first layers of the skin. MATERIALS AND METHODS: Data were picked from a previous study that included 35 healthy subjects who underwent a 3T MRI (multi spin echo calculation T2-weighted sequence) with a microscopic coil on the left heel before and one hour after moisturization...
January 18, 2019: Skin Research and Technology
Alexandr Alekhin, Ilya Razdolski, Marco Berritta, Damian Buerstel, Vasily Temnov, Detlef Diesing, Uwe Bovensiepen, Georg Woltersdorf, Peter Oppeneer, Alexey Melnikov
We demonstrate a novel method for the excitation of sizable magneto-optical effects in Au by means of the laser-induced injection of hot spin-polarized electrons in Au/Fe/MgO(001) heterostructures. It is based on the energy- and spin-dependent electron transmittance of Fe/Au interface which acts as a spin filter for non-thermalized electrons optically excited in Fe. We show that after crossing the interface, majority electrons propagate through the Au layer with the velocity on the order of 1~nm/fs (close to the Fermi velocity) and the decay length on the order of 100 nm...
January 9, 2019: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Tiancheng Song, Wei-Yuan Tu, Caitlin Carnahan, Xinghan Cai, Takashi Taniguchi, Kenji Watanabe, Michael A McGuire, David H Cobden, Di Xiao, Wang Yao, Xiaodong Xu
Atomically thin chromium triiodide (CrI3) has recently been identified as a layered antiferromagnetic insulator, in which adjacent ferromagnetic monolayers are antiferromagnetically coupled. This unusual magnetic structure naturally comprises a series of anti-aligned spin filters which can be utilized to make spin-filter magnetic tunnel junctions with very large tunneling magnetoresistance (TMR). Here we report voltage control of TMR formed by four-layer CrI3 sandwiched by monolayer graphene contacts in a dual-gated structure...
January 8, 2019: Nano Letters
Arwa Qasim, Inbal Sher, Orel Hirschhorn, Hadassa Shaked, Zena Qasem, Sharon Ruthstein, Jordan Chill
The bacterial potassium channel KcsA is gated by pH, opening for conduction under acidic conditions. Molecular determinants responsible for this effect have been identified at the extracellular selectivity filter, at the membrane-cytoplasm interface (TM2-gate), and in the cytoplasmic C-terminal domain (CTD), an amphiphilic four-helix bundle mediated by hydrophobic and electrostatic interactions. Here we employ nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) to provide a structural view of the pH-induced open-to-closed CTD transition...
November 22, 2018: Chembiochem: a European Journal of Chemical Biology
R G Kryshtal, A V Medved
Surface acoustic waves (SAW) in dynamic magnonic crystals (DMC) are considered for their use to create tunable spin-wave gadgets for processing of microwave signals. To understand the principles of operation of the proposed gadgets, the necessary basic properties of DMC created by a SAW in the structure of "yttrium iron garnet film on a substrate of gallium gadolinium garnet" are given. The prototype of the unique nonreciprocal notch filter working in the range of 3600-4100 MHz at the biasing magnetic field of 640 Oe is fabricated and its main characteristics such as dependences of the frequency and the depth of rejection pits on the frequency and power of the controlling SAW are measured...
December 4, 2018: Ultrasonics
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