IEEE Magnetics Letters最新文献

{"title":"Theoretical Circuit Design of an Efficient Spintronic Random Number Generator With an Internal Postprocessing Unit","authors":"Saeed Mehri;Abdolah Amirany;Mohammad Hossein Moaiyeri;Kian Jafari","doi":"10.1109/LMAG.2022.3200326","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3200326","url":null,"abstract":"In this letter, a spintronic true random number generator (TRNG) is designed using the stochastic switching feature of the magnetic tunnel junction device in the subcritical current regime. The proposed structure consumes low power and occupies a small area. Also, to improve the quality of random numbers production and compensate for the impact of process variations on the quality of the random output, the proposed TRNG includes an internal postprocessing unit. Compared to state-of-the-art designs, using an internal postprocessing unit reduces the proposed generator's area overhead and power consumption. The simulation results show that the TRNG proposed in this letter consumes up to 68% less power and occupies up to 64% smaller area than the state-of-the-art design. Also, due to the existence of the efficient postprocessing unit, the proposed TRNG successfully passes the National Institute of Standards and Technology random number tests even in the presence of the fabrication process variations.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67740925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longitudinal Transformation of Magnetic Properties in Magnetic Microwires With Graded Magnetic Anisotropy","authors":"Alexander Chizhik;Paula Corte-León;Valentina Zhukova;Julian Gonzalez;Arcady Zhukov","doi":"10.1109/LMAG.2022.3199170","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3199170","url":null,"abstract":"We studied the magneto-optical and magnetic behavior of Co- and Fe-rich microwires that were stress-annealed at temperatures distributed along the microwire length. There was a transformation of the magnetic structure across zones subjected to annealing at different temperatures. Differences in the magnetic behavior between the surface and bulk were observed for both Co- and Fe-rich microwires. The formation and subsequent transformation of a helical magnetic structure were observed, depending on the type of microwire. Annealing at temperatures below 100 °C affected the magnetic system of microwires. This effect is due to a weak but noticeable relaxation of the initial stresses in all parts of the microwire that even occurs in the low temperature range.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Safety Assessment of H-Coil for Nursing Staff in Deep Transcranial Magnetic Stimulation","authors":"Mai Lu;Shoogo Ueno","doi":"10.1109/LMAG.2022.3198370","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3198370","url":null,"abstract":"This work investigates the exposure experienced by the nursing staff executing deep transcranial magnetic stimulations (TMS) using H-coil. The safety assessment was implemented by employing the H-coil and realistic human model. The 144 relative positions of the H-coil with respect to the TMS operator body were considered, including the distance and vertical height. Dependence of the magnetic flux density and induced electric fields in the human model were obtained by using the impedance method. Results were compared with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. Regarding the occupational exposure, safe distances of 120 and 100 cm are derived from the ICNIRP reference level (RL) and basic restriction (BR), respectively. At the distance of 100 cm, the exposure level does not exceed the ICNIRP BR, and although the exposure level exceeds the RL, continued exposure is allowed. The findings suggest that nursing staff should stand at least 100 cm apart from the H-coil.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/5165412/9656771/09857568.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of Magnetic Resonance Sounding With a Delayed Adiabatic Pulse","authors":"Benquan Yang;Yujing Yang","doi":"10.1109/LMAG.2022.3196597","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3196597","url":null,"abstract":"Magnetic resonance sounding (MRS) is used to identify groundwater by exciting and measuring the nuclear magnetic resonance of hydrogen nuclei in subsurface aquifers. However, the MRS response is particularly weak and has a low signal-to-noise ratio (SNR); therefore, signal enhancement methods, such as adiabatic pulses, are essential for MRS applications with strong interference. The key challenges of utilizing this novel method are to increase the MRS signal response and sensitivity for field measurements. In this letter, we present an improved transmitting mode of a commonly used adiabatic half-passage pulse by combining this pulse with an earlier fixed frequency off-resonant pulse of short duration, thereby increasing the theoretical MRS sensitivity. Simulation results demonstrate that the approach could be used to further improve the signal responses, i.e., in terms of the SNR and potential resolution, for MRS exploration of high-noise environments.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67902596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two Modes of Drag Reduction for Magnetorheological Fluids","authors":"Jing Cheng Lv;Ming Yu Wu;Tong Zhao;Yin Tao Wei","doi":"10.1109/LMAG.2022.3193954","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3193954","url":null,"abstract":"Magnetorheological fluids (MRFs) show a millisecond-level reversible response controlled by an external magnetic field and are, thus, widely used in many areas, especially vehicle dampers, clutches, and brakes. However, in the standby state, the piston or rotor of these devices still moves in the MRF and generates damping force or torque, which will deteriorate the performance and even significantly increase the energy consumption of the entire vehicle. To solve these problems, we propose two working modes of MRFs based on rheology: vertical shear and parallel shear modes. We designed relevant magnetic circuit implementations for drum-type rotary magnetorheological (MR) devices to realize these new modes and verified the drag reduction effects by using a modified rheometer. The experimental results indicate that the vertical shear and parallel shear modes reduce the drag torque of the MRF by approximately 10% and 9% at magnetic field strengths of approximately 3.5 and 0.1 kA/m, respectively. Therefore, MR devices utilizing these drag reduction modes can reduce standby damping to improve performance. In addition, two mechanisms were developed to explain the significant decrease in damping torque with the increasing number of experiments under the vertical shear mode. In summary, research into these two modes promotes understanding of MRFs and the development of MR devices.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Construction of Energy Loops Using Magnetic Barkhausen Noise","authors":"Xiaoge Meng;Lin Li;Yanzhao Hou","doi":"10.1109/LMAG.2022.3191281","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3191281","url":null,"abstract":"Magnetic Barkhausen noise (MBN), which contains microstructure information of materials, is widely used in nondestructive testing (NDT) of magnetic materials. MBN energy (MBN\u0000_energy\u0000) is a time-independent indicator for NDT, but the initial MBN\u0000_energy\u0000 has no clear physical meaning and cannot be used to explain the relationship to the hysteresis loop. In this letter, based on the physical mechanism of MBN, a proportional relation is built between the MBN voltage signal \u0000<italic>V</i>\u0000_B\u0000 and energy loss, and the signal \u0000<italic>V</i>\u0000_B\u0000 is then related to the energy loss through wall pinning in the Jiles–Atherton hysteresis model. We define a novel magnetic Barkhausen noise energy eigenvalue (MBNE\u0000<italic>)</i>\u0000 as the time integral of the product of the absolute value of \u0000<italic>V</i>\u0000_B\u0000 and the sign function sign(\u0000<italic>dH</i>\u0000/\u0000<italic>dt</i>\u0000). We prove that the MBNE is proportional to the irreversible magnetization \u0000<italic>M</i>\u0000_irr\u0000. Since \u0000<italic>M</i>\u0000_irr\u0000 is equal to the saturation magnetization \u0000<italic>M</i>\u0000_s\u0000 when the magnetization of ferromagnetic material reaches saturation, we scaled the MBNE to make its maximum value equal to \u0000<italic>M</i>\u0000_s\u0000 and found that MBNE with respect to the magnetic field \u0000<italic>H</i>\u0000, MBNE(\u0000<italic>H</i>\u0000), coincides with the irreversible hysteresis loop \u0000<italic>M</i>\u0000_irr\u0000(\u0000<italic>H</i>\u0000). We refer to MBNE(\u0000<italic>H</i>\u0000) as the MBN energy loop. The MBNE(\u0000<italic>H</i>\u0000) and \u0000<italic>M</i>\u0000_irr\u0000(\u0000<italic>H</i>\u0000) for two kinds of electrical steel sheets are compared experimentally, which validates the adaptability of the MBNE(\u0000<italic>H</i>\u0000) construction method. The method to obtain \u0000<italic>M</i>\u0000_irr\u0000(\u0000<italic>H</i>\u0000) from the MBN raw signal reveals the physical mechanism of MBN and the irreversible magnetization process of magnetic materials.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a Temperature Sensor Using Spin-Crossover Fe(pyrazine)[Pt(CN)4I] Nanoparticles","authors":"Yunji Eom;Keonmok Kim;Hyeon-Jun Lee;Sri Ramulu Torati;CheolGi Kim","doi":"10.1109/LMAG.2022.3189274","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3189274","url":null,"abstract":"Device miniaturization requires temperature sensors with high resolution and precise calibration for measurements at reduced scale. We developed an optical temperature sensor using Fe\u0000²⁺\u0000 spin-crossover (SCO) material that has low and high spin states depending on temperature. We adjusted the operating range of the SCO (295–365 K) with an appropriate concentration of iodine. The color induced by temperature change was observed with a microscope and was converted to the color intensity represented in grayscale. To test the material, we covered the surface of a gold microheater with a layer of Fe(pyrazine)[Pt(CN)\u0000₄\u0000I] SCO nanoparticles and compared optically measured temperatures with those from a conventional temperature sensor. We conclude that the thermochromic temperature sensor is suitable for measuring temperature changes in microdevices, even in ambient light.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Normal Stress of a Micro–Nano Magnetorheological Elastomer","authors":"Xuhui Liu;Jinghu Wang;Huina Hu;Ziyun Fang;Bin Xu;Yan Wu;Lei Gao;Meiling Pu","doi":"10.1109/LMAG.2022.3184259","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3184259","url":null,"abstract":"A micro–nano magnetorheological elastomer (MRE) containing Fe\u0000₃\u0000O\u0000₄\u0000 nanoparticles was prepared, and its mechanical properties were analyzed. A microscopic static force model was used for MREs with different concentrations of nanomagnetic particles. To investigate the mechanical properties, an experimental platform was built, and its magnetic field flux was simulated with finite-element software. The results show that the maximum compressive elastic modulus for MREs containing 10% Fe\u0000₃\u0000O\u0000₄\u0000 nanoparticles is 2.89 MPa, which is 149% that of a traditional MRE under the same magnetic field. The normal stress of micro–nano MRE was significantly improved, which could be useful in the development of high-performance MREs.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2022-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Optimized Magnet Circuit Design to Reduce Power Consumption for Torsional Electromagnetic Actuators","authors":"Xian Shi;Guifu Ding","doi":"10.1109/LMAG.2022.3183493","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3183493","url":null,"abstract":"A torsional electromagnetic actuator that is actuated by the torque applied to a planar coil in an external magnetic field is designed, modeled, and analyzed in this letter. The analytical model of the magnetic torque is established. A magnet combination consisting of a rectangular magnet and a square-ring magnet magnetized in opposite directions is developed. A novel magnetic circuit is designed and analyzed to increase the driving torque. The electromagnetic and mechanical responses of the device are characterized by finite element simulation. In the case study, the power consumption of the actuator is significantly reduced by 54.3%, and down to 3.05 mW at the mechanical torsion angle of 11°. The effect of air gap on power consumption is also studied quantitatively.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic Phase Transitions in GdH0.15: Some Peculiarities in the Behavior of Magnetocaloric and Magnetostrictive Effects","authors":"Galina A. Politova;Irina S. Tereshina;Evgenia A. Tereshina-Chitrova;Barbora Vondráčková;Jiří Pospíšil;Mikhail A. Paukov;Alexander V. Andreev","doi":"10.1109/LMAG.2022.3171089","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3171089","url":null,"abstract":"The magnetocaloric effect (MCE) and anomalies of magnetostriction behavior were studied at the order-order and order-disorder magnetic phase transitions in hydrided Gd single crystal grown by a modified Czochralski method. The composition GdH\u0000_0.15\u0000 was obtained using a Sievert-type apparatus. While parent Gd shows an isotropic MCE at the order-disorder phase transition, the effect is anisotropic in GdH\u0000_0.15\u0000 due to the appearance of local anisotropy. We investigate in detail the temperature variation of the longitudinal, transverse, volume, and anisotropic magnetostriction. Hydrogenation is found to influence both the magnitude and the sign of the magnetostriction constants \u0000<inline-formula><tex-math>$lambda_{rm ij}^{alpha}$</tex-math></inline-formula>\u0000.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67901202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}