Several researchers have recently studied high-temperature (HT) motor drive systems under harsh temperature environments. We experimentally and numerically investigate iron loss and the magnetic hysteretic properties of amorphous magnetic materials (AMM) at room temperature (RT) and HT under pulse width modulation (PWM) inverter excitation. We demonstrate that the iron loss of AMM core fed by PWM inverter decreases as temperature increases similar like in the sinusoidal case. In addition, the temperature dependence of the B − H hysteresis curves of AMM under PWM inverter excitation relies not only on major loops but also on minor loops. Because the current at 300 ◦ C is higher than that at RT, the torque of the motor with AMM at HT becomes large at a few operating points. To realize low iron loss of HT motor drive systems, it is important to reduce eddy current losses of AMM cores at HT under PWM inverter excitation compared with the cases at RT. These results facilitate further research in iron loss reduction of motor systems based on studies of magnetic properties at HT under PWM inverter excitation. and HS under a
{"title":"Iron Loss and Hysteresis Properties of an Amorphous Ring Core at High Temperatures under Inverter Excitation","authors":"A. Yao","doi":"10.3379/msjmag.2003l002","DOIUrl":"https://doi.org/10.3379/msjmag.2003l002","url":null,"abstract":"Several researchers have recently studied high-temperature (HT) motor drive systems under harsh temperature environments. We experimentally and numerically investigate iron loss and the magnetic hysteretic properties of amorphous magnetic materials (AMM) at room temperature (RT) and HT under pulse width modulation (PWM) inverter excitation. We demonstrate that the iron loss of AMM core fed by PWM inverter decreases as temperature increases similar like in the sinusoidal case. In addition, the temperature dependence of the B − H hysteresis curves of AMM under PWM inverter excitation relies not only on major loops but also on minor loops. Because the current at 300 ◦ C is higher than that at RT, the torque of the motor with AMM at HT becomes large at a few operating points. To realize low iron loss of HT motor drive systems, it is important to reduce eddy current losses of AMM cores at HT under PWM inverter excitation compared with the cases at RT. These results facilitate further research in iron loss reduction of motor systems based on studies of magnetic properties at HT under PWM inverter excitation. and HS under a","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91175706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We fabricated fully epitaxial Fe/ZnO/MgO/Fe magnetic tunnel junctions (MTJs) with low junction resistance-area products (several $Omega$ $mu$m$^2$) and conducted a theoretical estimation of square-low rectifying performance for a terahertz electromagnetic wave. Effective current responsivity up to 0.09 A/W at 1 THz was obtained under zero-bias voltage condition at room temperature. The result is approximately half the value of the best result obtained for experiments in semiconductor-based diodes, performed under similar conditions. The study strongly suggests that this MTJ system has a great potential for the rectifying element of the terahertz wave.
我们制作了具有低结阻面积积(若干$Omega$$mu$ m $^2$)的全外延Fe/ZnO/MgO/Fe磁性隧道结(MTJs)，并对太赫兹电磁波的低平方整流性能进行了理论估计。在室温条件下，零偏置电压下的有效电流响应率高达0.09 A/W。结果大约是在类似条件下进行的半导体基二极管实验中获得的最佳结果的一半。该研究强烈表明，该MTJ系统对太赫兹波的整流元件具有很大的潜力。
{"title":"Estimation of Rectifying Performance for Terahertz Wave in Newly Designed Fe/ZnO/MgO/Fe Magnetic Tunnel Junction","authors":"Hidekazhi Saito, H. Imamura","doi":"10.3379/msjmag.2003l001","DOIUrl":"https://doi.org/10.3379/msjmag.2003l001","url":null,"abstract":"We fabricated fully epitaxial Fe/ZnO/MgO/Fe magnetic tunnel junctions (MTJs) with low junction resistance-area products (several $Omega$ $mu$m$^2$) and conducted a theoretical estimation of square-low rectifying performance for a terahertz electromagnetic wave. Effective current responsivity up to 0.09 A/W at 1 THz was obtained under zero-bias voltage condition at room temperature. The result is approximately half the value of the best result obtained for experiments in semiconductor-based diodes, performed under similar conditions. The study strongly suggests that this MTJ system has a great potential for the rectifying element of the terahertz wave.","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91157190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Nishimura, M. Haruta, Duck-Ho Kim, Y. Shiota, Hiroyuki Iwaki, D. Kan, T. Moriyama, Hiroki Kurata, T. Ono
We developed ferrimagnetic [Co(0.5)/Gd(1)/Pt(1)]N (unit: nm) multilayers with structural inversion symmetry breaking and investigated the dependence of magnetic properties and magnetic domain structures on the repetition number (N = 1 – 50). The magnetization compensation temperature increases as N increases, and saturates at around 210 K for N ≥ 20. All films with various repetition number possess the out-of-plane magnetic easy axis, and multi domain structure at the remanence state was observed in the film with N = 50. These results show that the magnetic properties of the ferrimagnetic Co/Gd/Pt multilayers can be tuned by the repetition number.
{"title":"Fabrication of Ferrimagnetic Co/Gd/Pt Multilayers with Structural Inversion Symmetry Breaking","authors":"T. Nishimura, M. Haruta, Duck-Ho Kim, Y. Shiota, Hiroyuki Iwaki, D. Kan, T. Moriyama, Hiroki Kurata, T. Ono","doi":"10.3379/msjmag.2001r002","DOIUrl":"https://doi.org/10.3379/msjmag.2001r002","url":null,"abstract":"We developed ferrimagnetic [Co(0.5)/Gd(1)/Pt(1)]N (unit: nm) multilayers with structural inversion symmetry breaking and investigated the dependence of magnetic properties and magnetic domain structures on the repetition number (N = 1 – 50). The magnetization compensation temperature increases as N increases, and saturates at around 210 K for N ≥ 20. All films with various repetition number possess the out-of-plane magnetic easy axis, and multi domain structure at the remanence state was observed in the film with N = 50. These results show that the magnetic properties of the ferrimagnetic Co/Gd/Pt multilayers can be tuned by the repetition number.","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"25 1","pages":"9-14"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91001255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents millimeter-scale small magnetic shields for electrical components such as magnetic sensors or magnetic random-access memories (MRAM). A prototype of a shielded package consisting of two shield pieces is fabricated by using a MEMS package assembly line. The shielded package exhibits anisotropic magnetic shielding effectiveness (MSE). Two magnetic circuit models are introduced to explain the cause of the anisotropic MSE. The models reveal that magnetic flux flow and magnetic reluctances are changed by an external magnetic field, which causes anisotropic MSE.
{"title":"Discussion on Anisotropic Magnetic Shielding Effectiveness of Shielded Package Analyzed by Magnetic Circuit Calculation","authors":"K. Yamada, Y. Fuji, M. Hara","doi":"10.3379/msjmag.2001r003","DOIUrl":"https://doi.org/10.3379/msjmag.2001r003","url":null,"abstract":"This paper presents millimeter-scale small magnetic shields for electrical components such as magnetic sensors or magnetic random-access memories (MRAM). A prototype of a shielded package consisting of two shield pieces is fabricated by using a MEMS package assembly line. The shielded package exhibits anisotropic magnetic shielding effectiveness (MSE). Two magnetic circuit models are introduced to explain the cause of the anisotropic MSE. The models reveal that magnetic flux flow and magnetic reluctances are changed by an external magnetic field, which causes anisotropic MSE.","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"169 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86066708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In microwave assisted magnetic recording (MAMR), it is still a challenge to obtain stable oscillation of magnetization in the spin torque oscillator (STO). In this paper we point out that one possible problem in practical MAMR heads is oscillation disturbance by transmitted spins from the head poles, i.e. the main pole and trailing shield, and also discuss the requirements for good STO oscillation. We propose structure design candidates with a short spin-diffusion length material and with a negative spin-polarization material to obtain a larger microwave assist field generated from the STO using micromagnetics simulation.
{"title":"Effect of Transmitted Spin from Head Poles in MAMR","authors":"I. Tagawa","doi":"10.3379/msjmag.2001r001","DOIUrl":"https://doi.org/10.3379/msjmag.2001r001","url":null,"abstract":"In microwave assisted magnetic recording (MAMR), it is still a challenge to obtain stable oscillation of magnetization in the spin torque oscillator (STO). In this paper we point out that one possible problem in practical MAMR heads is oscillation disturbance by transmitted spins from the head poles, i.e. the main pole and trailing shield, and also discuss the requirements for good STO oscillation. We propose structure design candidates with a short spin-diffusion length material and with a negative spin-polarization material to obtain a larger microwave assist field generated from the STO using micromagnetics simulation.","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82968087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Generating a magnetic field with a desired magnitude and direction in a plane by using a mangle-type magnetic field source with four permanent magnets is discussed. Two rotation patterns were compared by using a 2D finite element method in terms of the controllability of the magnetic field and the uniformity of the generated magnetic field. In both patterns, the arrangement of magnets that generates the maximum magnetic field corresponds to a Halbach cylinder. It was found that one of the rotation patterns is superior for controlling the magnitude and direction of the magnetic field independently, while it is inferior in terms of uniformity. Finally, the above findings were demonstrated with a prototype, although a slight deviation was seen between the simulation and the demonstration.
{"title":"Generation of 2D Vector Magnetic Field by Mangle-Type Magnetic Field Source Using Permanent Magnets","authors":"H. Sakuma","doi":"10.3379/msjmag.2001r004","DOIUrl":"https://doi.org/10.3379/msjmag.2001r004","url":null,"abstract":"Generating a magnetic field with a desired magnitude and direction in a plane by using a mangle-type magnetic field source with four permanent magnets is discussed. Two rotation patterns were compared by using a 2D finite element method in terms of the controllability of the magnetic field and the uniformity of the generated magnetic field. In both patterns, the arrangement of magnets that generates the maximum magnetic field corresponds to a Halbach cylinder. It was found that one of the rotation patterns is superior for controlling the magnitude and direction of the magnetic field independently, while it is inferior in terms of uniformity. Finally, the above findings were demonstrated with a prototype, although a slight deviation was seen between the simulation and the demonstration.","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78242428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We studied the Curie temperature T C variation in L 1 0 -type FePt ordered alloys that were partially substituted with other transition metal elements, such as Mn, Cu, Ru, and Rh, by first-principles calculations. For the theoretical evaluation of T C , a disordered local moment approach based on the coherent potential approximation was employed. The calculated results reveal that the most significant reduction in T C was observed for FePt where some Pt was substituted by Ru, while a large uniaxial magnetic anisotropy constant on the order of 10 7 erg / cm 3 was maintained. An analysis of the electronic structure demonstrates that the stability of the ferromagnetic state is degraded by the substitution of Ru.
{"title":"First-Principles Calculation of Curie Temperature Tuning in L10-Type FePt by Element Substitution of Mn, Cu, Ru, and Rh","authors":"Y. Kota","doi":"10.3379/msjmag.2001l005","DOIUrl":"https://doi.org/10.3379/msjmag.2001l005","url":null,"abstract":"We studied the Curie temperature T C variation in L 1 0 -type FePt ordered alloys that were partially substituted with other transition metal elements, such as Mn, Cu, Ru, and Rh, by first-principles calculations. For the theoretical evaluation of T C , a disordered local moment approach based on the coherent potential approximation was employed. The calculated results reveal that the most significant reduction in T C was observed for FePt where some Pt was substituted by Ru, while a large uniaxial magnetic anisotropy constant on the order of 10 7 erg / cm 3 was maintained. An analysis of the electronic structure demonstrates that the stability of the ferromagnetic state is degraded by the substitution of Ru.","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88089587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Hung, Tian Li, R. Hisatomi, Y. Shiota, T. Moriyama, T. Ono
{"title":"Low Current Driven Vertical Domain Wall Motion Memory with an Artificial Ferromagnet","authors":"Y. Hung, Tian Li, R. Hisatomi, Y. Shiota, T. Moriyama, T. Ono","doi":"10.3379/msjmag.2011r002","DOIUrl":"https://doi.org/10.3379/msjmag.2011r002","url":null,"abstract":"","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78544051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Micromagnetic Simulation of Voltage-Induced Spin Wave Resonance Properties in Ferromagnetic Nanowires with Perpendicular Anisotropy","authors":"X. Ya, R. Imai, Terumitsu Tanaka, K. Matsuyama","doi":"10.3379/msjmag.2003r004","DOIUrl":"https://doi.org/10.3379/msjmag.2003r004","url":null,"abstract":"","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"13 1","pages":"40-44"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74856040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Information Stability in Heat-Assisted Magnetic Recording","authors":"T. Kobayashi, Y. Nakatani, Y. Fujiwara","doi":"10.3379/msjmag.1911r003","DOIUrl":"https://doi.org/10.3379/msjmag.1911r003","url":null,"abstract":"","PeriodicalId":36791,"journal":{"name":"Journal of the Magnetics Society of Japan","volume":"42 Suppl 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88678692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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