scholarly journals Detecting halfmetallic electronic structures of spintronic materials in a magnetic field

2021 ◽  
Author(s):  
Hidenori Fujiwara ◽  
Rie Umetsu ◽  
Fumiaki Kuroda ◽  
Jun Miyawaki ◽  
Toshiyuki Kashiuchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Band Gap ◽  
Electric Fields ◽  
Electronic Structures ◽  
Degrees Of Freedom ◽  
Magnetic Circular Dichroism ◽  
Spectroscopic Technique ◽  
Promising Tool ◽  
Magnetic Layers ◽  
Spin Polarized

Abstract Band-gap engineering is one of the fundamental techniques in semiconductor technology and also applicable in the next generation spintronics using the spin degrees of freedom. To fully utilize the spintronic material, it is essential to optimize the spin-dependent electronic structures in the operando conditions by applying the magnetic and/or electric fields. Here we present a new spectroscopic technique to probe the spin-polarized electronic structures by using magnetic circular dichroism (MCD) in the resonant inelastic soft X-ray scattering (RIXS) under an external magnetic field. Thanks to the spin-selective dipole-allowed transitions in the RIXS-MCD, we have successfully demonstrated the direct evidence of the perfectly spin-polarized electronic structures for the prototypical halfmetallic Heusller alloy, Co2MnSi. The RIXS-MCD is a promising tool to probe the spin-dependent carriers and band-gap with element specific way induced in the buried magnetic layers under the operando conditions.

scholarly journals Detecting halfmetallic electronic structures of spintronic materials in a magnetic field

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
H. Fujiwara ◽  
R. Y. Umetsu ◽  
F. Kuroda ◽  
J. Miyawaki ◽  
T. Kashiuchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Band Gap ◽  
Electric Fields ◽  
Electronic Structures ◽  
Magnetic Circular Dichroism ◽  
Spectroscopic Technique ◽  
Band Gap Engineering ◽  
Promising Tool ◽  
Magnetic Layers ◽  
Spin Polarized

AbstractBand-gap engineering is one of the fundamental techniques in semiconductor technology and also applicable in next generation spintronics using the spin degree of freedom. To fully utilize the spintronic materials, it is essential to optimize the spin-dependent electronic structures in the operando conditions by applying magnetic and/or electric fields. Here we present an advanced spectroscopic technique to probe the spin-polarized electronic structures by using magnetic circular dichroism (MCD) in resonant inelastic soft X-ray scattering (RIXS) under an external magnetic field. Thanks to the spin-selective dipole-allowed transitions in RIXS-MCD, we have successfully demonstrated the direct evidence of the perfectly spin-polarized electronic structures for the prototypical halfmetallic Heusller alloy $$\hbox {Co}_2\hbox {MnSi}$$ Co 2 MnSi . RIXS-MCD is a promising tool to probe the spin-dependent carriers and band-gap induced in the buried magnetic layers in an element specific way under the operando conditions.

scholarly journals Isospin magnetism and spin-polarized superconductivity in Bernal bilayer graphene

Science ◽  
2022 ◽  
Author(s):  
Haoxin Zhou ◽  
Ludwig Holleis ◽  
Yu Saito ◽  
Liam Cohen ◽  
William Huynh ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Order Parameter ◽  
Degrees Of Freedom ◽  
Bilayer Graphene ◽  
Zero Magnetic Field ◽  
Cooper Pairing ◽  
Two Dimensional ◽  
Van Hove Singularity ◽  
Spin Polarized ◽  
Spin Triplet

In conventional superconductors, Cooper pairing occurs between electrons of opposite spin. We observe spin-polarized superconductivity in Bernal bilayer graphene when doped to a saddle-point van Hove singularity generated by large applied perpendicular electric field. We observe a cascade of electrostatic gate-tuned transitions between electronic phases distinguished by their polarization within the isospin space defined by the combination of the spin and momentum-space valley degrees of freedom. Although all of these phases are metallic at zero magnetic field, we observe a transition to a superconducting state at finite B ‖ ≈ 150mT applied parallel to the two-dimensional sheet. Superconductivity occurs near a symmetry breaking transition, and exists exclusively above the B ‖ -limit expected of a paramagnetic superconductor with the observed transition temperature T C ≈ 30mK, consistent with a spin-triplet order parameter.

scholarly journals Magnetic Nanodiscs—A New Promising Tool for Microsurgery of Malignant Neoplasms

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1459
Author(s):  
Tatiana N. Zamay ◽  
Vladimir S. Prokopenko ◽  
Sergey S. Zamay ◽  
Kirill A. Lukyanenko ◽  
Olga S. Kolovskaya ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Remote Control ◽  
Tumor Cells ◽  
Biological Effects ◽  
Malignant Neoplasms ◽  
Rotating Magnetic Fields ◽  
Magnetic Structures ◽  
Promising Tool

Magnetomechanical therapy is one of the most perspective directions in tumor microsurgery. According to the analysis of recent publications, it can be concluded that a nanoscalpel could become an instrument sufficient for cancer microsurgery. It should possess the following properties: (1) nano- or microsized; (2) affinity and specificity to the targets on tumor cells; (3) remote control. This nano- or microscalpel should include at least two components: (1) a physical nanostructure (particle, disc, plates) with the ability to transform the magnetic moment to mechanical torque; (2) a ligand—a molecule (antibody, aptamer, etc.) allowing the scalpel precisely target tumor cells. Literature analysis revealed that the most suitable nanoscalpel structures are anisotropic, magnetic micro- or nanodiscs with high-saturation magnetization and the absence of remanence, facilitating scalpel remote control via the magnetic field. Additionally, anisotropy enhances the transmigration of the discs to the tumor. To date, four types of magnetic microdiscs have been used for tumor destruction: synthetic antiferromagnetic P-SAF (perpendicular) and SAF (in-plane), vortex Py, and three-layer non-magnetic–ferromagnet–non-magnetic systems with flat quasi-dipole magnetic structures. In the current review, we discuss the biological effects of magnetic discs, the mechanisms of action, and the toxicity in alternating or rotating magnetic fields in vitro and in vivo. Based on the experimental data presented in the literature, we conclude that the targeted and remotely controlled magnetic field nanoscalpel is an effective and safe instrument for cancer therapy or theranostics.

scholarly journals A chiral switchable photovoltaic ferroelectric 1D perovskite

2020 ◽  
Vol 6 (9) ◽  
pp. eaay4213 ◽  
Author(s):  
Yang Hu ◽  
Fred Florio ◽  
Zhizhong Chen ◽  
W. Adam Phelan ◽  
Maxime A. Siegler ◽  
...  
Keyword(s):  
Electric Fields ◽  
Mirror Symmetry ◽  
Degrees Of Freedom ◽  
Electrical Measurements ◽  
Temperature Dependent ◽  
Paraelectric Phase Transition ◽  
Strongly Coupled ◽  
Yield Phenomena ◽  
Hybrid Perovskite ◽  
Low Dimensional

Spin and valley degrees of freedom in materials without inversion symmetry promise previously unknown device functionalities, such as spin-valleytronics. Control of material symmetry with electric fields (ferroelectricity), while breaking additional symmetries, including mirror symmetry, could yield phenomena where chirality, spin, valley, and crystal potential are strongly coupled. Here we report the synthesis of a halide perovskite semiconductor that is simultaneously photoferroelectricity switchable and chiral. Spectroscopic and structural analysis, and first-principles calculations, determine the material to be a previously unknown low-dimensional hybrid perovskite (R)-(−)-1-cyclohexylethylammonium/(S)-(+)-1 cyclohexylethylammonium) PbI3. Optical and electrical measurements characterize its semiconducting, ferroelectric, switchable pyroelectricity and switchable photoferroelectric properties. Temperature dependent structural, dielectric and transport measurements reveal a ferroelectric-paraelectric phase transition. Circular dichroism spectroscopy confirms its chirality. The development of a material with such a combination of these properties will facilitate the exploration of phenomena such as electric field and chiral enantiomer–dependent Rashba-Dresselhaus splitting and circular photogalvanic effects.

scholarly journals Double layers in the downward current region of the aurora

2003 ◽  
Vol 10 (1/2) ◽  
pp. 45-52 ◽  
Author(s):  
R. E. Ergun ◽  
L. Andersson ◽  
C. W. Carlson ◽  
D. L. Newman ◽  
M. V. Goldman
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Space ◽  
Electric Field ◽  
Electric Fields ◽  
Double Layers ◽  
Parallel Electric Field ◽  
Electrostatic Waves ◽  
Current Region ◽  
Decisive Evidence

Abstract. Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields organize into a structure of three distinct, narrowly-confined regions along the magnetic field (B). In the "ramp" region, the measured parallel electric field forms a nearly-monotonic potential ramp that is localized to ~ 10 Debye lengths along B. The ramp is moving parallel to B at the ion acoustic speed (vs) and in the same direction as the accelerated electrons. On the high-potential side of the ramp, in the "beam" region, an unstable electron beam is seen for roughly another 10 Debye lengths along B. The electron beam is rapidly stabilized by intense electrostatic waves and nonlinear structures interpreted as electron phase-space holes. The "wave" region is physically separated from the ramp by the beam region. Numerical simulations reproduce a similar ramp structure, beam region, electrostatic turbulence region and plasma characteristics as seen in the observations. These results suggest that large double layers can account for the parallel electric field in the downward current region and that intense electrostatic turbulence rapidly stabilizes the accelerated electron distributions. These results also demonstrate that parallel electric fields are directly associated with the generation of large-amplitude electron phase-space holes and plasma waves.

TRANSPARENCY OF NARROW CONSTRICTIONS IN A GRAPHENE SINGLE ELECTRON TRANSISTOR

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2647-2654 ◽  
Author(s):  
C. STAMPFER ◽  
E. SCHURTENBERGER ◽  
F. MOLITOR ◽  
J. GÜTTINGER ◽  
T. IHN ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Drain Current ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Perpendicular Magnetic Field ◽  
Current Saturation ◽  
Tunnel Barriers ◽  
Graphene Island ◽  
Charging Energy

We report on electronic transport experiments on a graphene single electron transistor as function of a perpendicular magnetic field. The device, which consists of a graphene island connected to source and drain electrodes via two narrow graphene constrictions is electronically characterized and the device exhibits a characteristic charging energy of approx. 3.5 meV. We investigate the homogeneity of the two graphene "tunnel" barriers connecting the single electron transistor to source and drain contacts as function of laterally applied electric fields, which are also used to electrostatically tune the overall device. Further, we focus on the barrier transparency as function of an applied perpendicular magnetic field and we find an increase of transparency for increasing magnetic field and a source-drain current saturation for magnetic fields exceeding 5 T.

Orientation Control in Multilayered Alumina Prepared Using Electrophoretic Deposition in a Strong Magnetic Field

2007 ◽  
Vol 29-30 ◽  
pp. 223-226
Author(s):  
Tohru Suzuki ◽  
Tetsuo Uchikoshi ◽  
Koji Morita ◽  
Keijiro Hiraga ◽  
Yoshio Sakka
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Electric Fields ◽  
Electrophoretic Deposition ◽  
Layer By Layer ◽  
Colloidal Processing ◽  
Orientation Control ◽  
Laminar Composites ◽  
Oriented Layer

We have reported that development of texture can be controlled by colloidal processing in a strong magnetic field followed by heating even for diamagnetic ceramics such as alumina, titania and so on. We demonstrate in this study that alumina/alumina laminar composites with different crystalline-oriented layer are produced by electrophoretic deposition (EPD) in a strong magnetic field. This composite was fabricated by alternately changing the angle between the directions of the magnetic and electric fields layer by layer during EPD in 12T. The grains in alternate layers are aligned differently.

A Case for Magneto Hydro Dynamics (MHD)

2001 ◽  
Author(s):  
Haim H. Bau
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Lorentz Force ◽  
Electric Fields ◽  
Biological Fluids ◽  
Fluid Volume ◽  
Chaotic Advection ◽  
Complex Flows ◽  
Electric Currents

Abstract In this paper, I review some of our work on the use of magneto hydrodynamics (MHD) for pumping, controlling, and stirring fluids in microdevices. In many applications, one operates with liquids that are at least slightly conductive such as biological fluids. By patterning electrodes inside flow conduits and subjecting these electrodes to potential differences, one can induce electric currents in the liquid. In the presence of a magnetic field, a Lorentz force is generated in a direction that is perpendicular to both the magnetic and electric fields. Since one has a great amount of freedom in patterning the electrodes, one can induce forces in various directions so as to generate complex flows including “guided” flows in virtual, wall-less channels. The magnetic flux generators can be either embedded in the device or be external. Despite their unfavorable scaling (the magnitude of the forces is proportional to the fluid volume), MHD offers many advantages such as the flexibility of applying forces in any desired direction and the ability to adjust the magnitude of the forces by adjusting either the electric and/or magnetic fields. We provide examples of (i) MHD pumps; (ii) controlled networks of conduits in which each conduit is equipped with a MHD actuator and by controlling the voltage applied to each actuator, one can direct the liquid to flow in any desired way without a need for valves; and (iii) MHD stirrers including stirrers that exhibit chaotic advection.

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