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Magnetic field sensor based on magnetoplasmonic crystal
摘要： Here we report on designing a magnetic field sensor based on magnetoplasmonic crystal made of noble and ferromagnetic metals deposited on one-dimensional subwavelength grating. The experimental data demonstrate resonant transverse magneto-optical Kerr effect (TMOKE) at a narrow spectral region of 50 nm corresponding to the surface plasmon-polaritons excitation and maximum modulation of the reflected light intensity of 4.5% in a modulating magnetic field with the magnitude of 16 Oe. Dependences of TMOKE on external alternating current (AC) and direct current (DC) magnetic field demonstrate that it is a possibility to use the magnetoplasmonic crystal as a high-sensitive sensing probe. The achieved sensitivity to DC magnetic field is up to 10?6 Oe at local area of 1 mm2.
关键词： sensitivity,surface plasmon-polaritons,transverse magneto-optical Kerr effect,magnetic field sensor,magnetoplasmonic crystal
更新于2025-09-23 15:21:01
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Terahertz Photoconductivity in Graphene in a Magnetic Field
摘要： The terahertz photoconductivity in epitaxial graphene grown on SiC substrates is investigated in a magnetic field. The magnetic-field dependence of the photoresponse signal amplitude is examined at different electron densities, bias currents, and terahertz radiation intensities. The experimental results are explained well by a photoconductivity mechanism based on the heating of electrons by terahertz radiation. A strong increase in the photoconductivity signal with increasing magnetic field caused by an increase in the relaxation time due to the suppression of electron-electron scattering is observed.
关键词： terahertz radiation,photoconductivity,magnetic field,graphene
更新于2025-09-23 15:21:01
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Control of current waveform of laser ion source using pulsed magnetic field
摘要： We investigated plasma behavior with a solenoid-generated static and pulsed magnetic field by measuring time evolution in a transverse ion current profile to control the ion current waveform of a laser ion source. The results showed that static magnetic fields cannot enhance the ion current in the slow region of time of flight (TOF). However, a pulsed magnetic field whose magnetic flux density is rising while a plasma passes through the solenoid can enhance the ion current in the same TOF region. The results showed that applying a pulsed magnetic field to a laser-produced plasma is an effective way to control an ion current waveform in a laser ion source to produce an ion beam with a flat-top-shaped pulse. By using a pulsed magnetic field, the ion current waveform peak was held for ～50 μs.
关键词： laser ion source,ion current waveform,pulsed magnetic field,plasma behavior
更新于2025-09-23 15:21:01
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Fiber Optic Magnetic Field Sensor Utilizing DFB Fiber Laser and Terfenol-D Material
摘要： We present a novel distributed feedback fiber laser (DFB-FL) fiber laser sensor, which can measure static magnetic field through sweep acoustic wave. A fiber laser is bonded on the giant magnetostrictive material Terfenol-D (Tb0.3Dy0.7Fe1.92) tube oriented along the longitudinal direction. When acoustic wave of different frequency is added to the fiber laser, it has the maximum response at its resonant frequency, which will vary with the external magnetic field. The measurement sensitivity of the sensor is 0.39 Hz/mT to the magnetic field. The experimental results also show that the sensor exhibits excellent linearity and directivity in response to static magnetic field.
关键词： fiber laser,Terfenol-D,magnetic field sensor
更新于2025-09-23 15:21:01
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Influence of Static Magnetic Field on the Microstructure of Nickel-Based Superalloy by Laser-Directed Energy Deposition
摘要： The influence of a static magnetic field on microstructure evolution during laser direct energy deposition was studied. Our results reveal that dendrite spacing increases with increasing magnetic field flux density (MFFD). Moreover, electron backscatter diffraction results reveal that the epitaxial growth was preferred with increasing MFFD. We discuss these findings in terms of the influence of a magnetic field on melt convection and propose that an applied magnetic field effectively limits Marangoni convection.
关键词： microstructure,static magnetic field,laser-directed energy deposition,dendrite spacing,Marangoni convection
更新于2025-09-23 15:21:01
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Gain of electron orbital angular momentum in a direct laser acceleration process
摘要： Three-dimensional “particle in cell” simulations show that a quasistatic magnetic ?eld can be generated in a plasma irradiated by a linearly polarized Laguerre-Gauss beam with a nonzero orbital angular momentum (OAM). Perturbative analysis of the electron dynamics in the low intensity limit and detailed numerical analysis predict a laser to electrons OAM transfer. Plasma electrons gain angular velocity thanks to the dephasing process induced by the combined action of the ponderomotive force and the laser induced–radial oscillation. Similar to the “direct laser acceleration,” where Gaussian laser beams transmit part of its axial momentum to electrons, Laguerre-Gaussian beams transfer a part of their orbital angular momentum to electrons through the dephasing process.
关键词： orbital angular momentum,electron dynamics,magnetic field generation,Laguerre-Gauss beam,plasma
更新于2025-09-23 15:21:01
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Effect of critical current spread on the noise performance of SQUID magnetometers: An experimental study
摘要： We investigate the noise performance dependence on the critical current spread of a fully integrated magnetometer based on superconducting quantum interference device (SQUID). In particular, we analyze the behavior of spectral density of magnetic field noise carrying out an experimental study on 200 magnetometers. The magnetic sensors consist of a superconducting flux transformer connected to a SQUID in a washer shape and include both a feedback coil for flux locked loop operation and an additional positive feedback circuit to increase the intrinsic voltage responsivity. A damping resistor in parallel to the SQUID inductance has been used in order to prevent both the degradation due to the non-optimal βL value and the washer resonances. Such sensors are often employed in magnetoencephalography or more in general in ultra-high sensitivity applications requiring the magnetic noise spectral density as low as 2 fT/√Hz in the white region. We will show that a SQUID critical current varying from 8 to 40 μA does not cause an evident degradation of the magnetometer sensibility. In addition, the magnetic field noise vs critical current indicates an optimal value of SQUID critical current of 20 μA. It corresponds to an inductance parameter βL of about 2 highlighting the effectiveness of the damping resistor in parallel to the SQUID inductance.
关键词： SQUIDs,Superconducting Magnetometers,Magnetic field noise
更新于2025-09-23 15:21:01
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Understanding degradation of organic light-emitting diodes from magnetic field effects
摘要： The impact of magnetic field effects on the electroluminescence of organic light-emitting diodes is commonly used to characterize exciton dynamics such as generation, annihilation, and performance degradation. However, interpreting these effects is challenging. Here, we show that magnetic field effects in organic light-emitting diodes can be understood in terms of the magnetic response of device characteristics derived from polaron-pair and triplet exciton quenching processes, such as triplet-polaron interactions and triplet-triplet annihilation. Device degradation shows a clear relationship with the amplitude of the magnetic field effects, enabling non-destructive measurement of the degradation. The results and proposed mechanism provide a better understanding of magnetic field effects on organic light-emitting diodes and device degradation phenomena.
关键词： magnetic field effects,device degradation,organic light-emitting diodes,triplet-polaron interactions,triplet-triplet annihilation,exciton dynamics
更新于2025-09-23 15:21:01
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Magnetic field compatible circuit quantum electrodynamics with graphene Josephson junctions
摘要： Circuit quantum electrodynamics has proven to be a powerful tool to probe mesoscopic effects in hybrid systems and is used in several quantum computing (QC) proposals that require a transmon qubit able to operate in strong magnetic fields. To address this we integrate monolayer graphene Josephson junctions into microwave frequency superconducting circuits to create graphene based transmons. Using dispersive microwave spectroscopy we resolve graphene’s characteristic band dispersion and observe coherent electronic interference effects confirming the ballistic nature of our graphene Josephson junctions. We show that the monoatomic thickness of graphene renders the device insensitive to an applied magnetic field, allowing us to perform energy level spectroscopy of the circuit in a parallel magnetic field of 1 T, an order of magnitude higher than previous studies. These results establish graphene based superconducting circuits as a promising platform for QC and the study of mesoscopic quantum effects that appear in strong magnetic fields.
关键词： transmon qubit,magnetic field resilience,quantum computing,Circuit quantum electrodynamics,graphene Josephson junctions
更新于2025-09-23 15:21:01
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Effect of Magnetic Field on Terahertz Photoconductivity in Hg<inf>l-x</inf>Cd<inf>x</inf>Te-Based Structures
摘要： In this paper, we show that the positive terahertz photoconductivity in Hg1-xCdxTe solid solutions being in a topological phase (x < 0.16) strongly depends on the combination of both the external magnetic field direction and the potential probe position. The asymmetry in the photoresponse in the magnetic field may be due to the spin-related features of the carriers excited.
关键词： topological phase,spin-related features,Hg1-xCdxTe,terahertz photoconductivity,magnetic field
更新于2025-09-23 15:21:01