Pub Date : 2023-01-02DOI: 10.1109/LMAG.2022.3233222
Nan N. Liu;Yulia A. Alekhina;Alexander P. Pyatakov;Nikolai S. Perov;Boris B. Kovalev;Gleb B. Sukhorukov;Alexander M. Tishin;Tomomasa Moriwaki;Kenta Nakazawa;Yuko Ichiyanagi
Magnetic and magnetothermal properties of annealed Zn 0.2 Mn 0.8 Fe 2 O 4 nanoparticles with diameter value, ranging from 9 to 35 nm, have been investigated and compared with earlier investigated unannealed Zn 0.2 Mn 0.8 Fe 2 O 4 magnetic nanoparticles (MNPs). A single-phase spinel structure was observed in both types of MNPs. It has been demonstrated that for the large annealed Zn 0.2 Mn 0.8 Fe 2 O 4 nanoparticles (24.7, 31.4, 35.1 nm) the value of specific absorption rate (SAR) is proportional to the amplitude of the magnetic field as ∼ H 4 . However, for earlier investigated unannealed Zn 0.2 Mn 0.8 Fe 2 O 4 MNPs, superquadratic dependence SAR ∼ H 5 have been found starting from 13 nm. Significant change of dependence of the character of SAR (d) may be explained by low values of hysteresis area of small annealed MNPs and, thus, dominant role of Néel relaxation in these annealed Zn 0.2 Mn 0.8 Fe 2 O 4 nanoparticles.
{"title":"Investigation of Impact of the Annealing on Magnetothermal Properties of Zn0.2Mn0.8Fe2O4 Nanoparticles","authors":"Nan N. Liu;Yulia A. Alekhina;Alexander P. Pyatakov;Nikolai S. Perov;Boris B. Kovalev;Gleb B. Sukhorukov;Alexander M. Tishin;Tomomasa Moriwaki;Kenta Nakazawa;Yuko Ichiyanagi","doi":"10.1109/LMAG.2022.3233222","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3233222","url":null,"abstract":"Magnetic and magnetothermal properties of annealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 nanoparticles with diameter value, ranging from 9 to 35 nm, have been investigated and compared with earlier investigated unannealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 magnetic nanoparticles (MNPs). A single-phase spinel structure was observed in both types of MNPs. It has been demonstrated that for the large annealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 nanoparticles (24.7, 31.4, 35.1 nm) the value of specific absorption rate (SAR) is proportional to the amplitude of the magnetic field as ∼\u0000<italic>H</i>\u0000<sup>4</sup>\u0000. However, for earlier investigated unannealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 MNPs, superquadratic dependence SAR ∼\u0000<italic>H</i>\u0000<sup>5</sup>\u0000 have been found starting from 13 nm. Significant change of dependence of the character of SAR\u0000<italic>(d)</i>\u0000 may be explained by low values of hysteresis area of small annealed MNPs and, thus, dominant role of Néel relaxation in these annealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 nanoparticles.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763010","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}
Pub Date : 2023-01-01DOI: 10.1109/LMAG.2024.3379164
{"title":"TechRxiv: Share Your Preprint Research with the World!","authors":"","doi":"10.1109/LMAG.2024.3379164","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3379164","url":null,"abstract":"","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-1"},"PeriodicalIF":1.2,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10477288","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140181515","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}
Pub Date : 2022-12-23DOI: 10.1109/LMAG.2022.3231819
Haochen Zhang;Yi Sun;Zhongzhou Du;Teruyoshi Sasayama;Takashi Yoshida
This work investigated chainlike magnetic nanoparticles (CMNPs), which are a type of magnetic nanoparticle (MNP) with a dipole–dipole interaction in which individual nanoparticles are connected to form a chainlike structure. We numerically analyzed the ac magnetization characteristics of the CMNP and the single-core MNP (SMNP) using the Landau–Lifshitz–Gilbert equation. Owing to the magnetic dipole–dipole interaction, the magnetization of the CMNP is approximately 10 times that of the SMNP under a certain excitation field. MNPs with a chainlike structure are thus expected to have enhanced magnetization characteristics and better performance in medical applications. Additionally, it was found that stronger magnetization can be expected from a CMNP connecting 10 or more magnetic cores with a size of approximately 10–12 nm.
{"title":"Numerical Study on the Magnetization Characteristics of Chainlike Magnetic Nanoparticles","authors":"Haochen Zhang;Yi Sun;Zhongzhou Du;Teruyoshi Sasayama;Takashi Yoshida","doi":"10.1109/LMAG.2022.3231819","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3231819","url":null,"abstract":"This work investigated chainlike magnetic nanoparticles (CMNPs), which are a type of magnetic nanoparticle (MNP) with a dipole–dipole interaction in which individual nanoparticles are connected to form a chainlike structure. We numerically analyzed the ac magnetization characteristics of the CMNP and the single-core MNP (SMNP) using the Landau–Lifshitz–Gilbert equation. Owing to the magnetic dipole–dipole interaction, the magnetization of the CMNP is approximately 10 times that of the SMNP under a certain excitation field. MNPs with a chainlike structure are thus expected to have enhanced magnetization characteristics and better performance in medical applications. Additionally, it was found that stronger magnetization can be expected from a CMNP connecting 10 or more magnetic cores with a size of approximately 10–12 nm.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67762119","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}
This letter presents a novel and compact structure that integrates silicon-carbide (SiC) Schottky diodes within a high-frequency transformer (HFT). The proposed structure would reduce the volume of a power converter and, in turn, the system to which it is applied. It would also greatly reduce the leakage inductances of an HFT as well as the inductive electromagnetic interference to surrounding components and devices. A prototype HFT shaped much like a torus is designed for integration with SiC Schottky diodes. The three-dimensional finite-element method simulation technique is used to design and analyze the magnetic structure of the HFT including the space reserved for the SiC Schottky diodes. Experimental results are presented for both the HFT as a separate component and as a system integrated with SiC Schottky diodes.
{"title":"Integration of Novel High-Frequency Transformer With Silicon-Carbide Schottky Diodes","authors":"Weichong Yao;Junwei Lu;Andrew Seagar;Feifei Bai;Foad Taghizadeh","doi":"10.1109/LMAG.2022.3229230","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3229230","url":null,"abstract":"This letter presents a novel and compact structure that integrates silicon-carbide (SiC) Schottky diodes within a high-frequency transformer (HFT). The proposed structure would reduce the volume of a power converter and, in turn, the system to which it is applied. It would also greatly reduce the leakage inductances of an HFT as well as the inductive electromagnetic interference to surrounding components and devices. A prototype HFT shaped much like a torus is designed for integration with SiC Schottky diodes. The three-dimensional finite-element method simulation technique is used to design and analyze the magnetic structure of the HFT including the space reserved for the SiC Schottky diodes. Experimental results are presented for both the HFT as a separate component and as a system integrated with SiC Schottky diodes.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67902597","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}
Pub Date : 2022-12-13DOI: 10.1109/LMAG.2022.3225742
Hans T. Nembach;Justin M. Shaw;Chloe S. Taylor;Daniel B. Gopman
Ultrathin Ta/CoFeB/Pt trilayer structures are relevant to a wide range of spintronic applications, from magnetic tunnel junctions to skyrmionics devices. Controlling the perpendicular magnetic anisotropy, Gilbert damping, and Dzyaloshinskii–Moriya interaction (DMI) in the CoFeB layer is key for these applications. We examine the role of sputter gas composition during the Pt overlayer deposition of a Ta/CoFeB/Pt trilayer in Ar, Kr, and Xe working gas environments during direct current magnetron sputtering. The decreasing density of the Pt layer (from 21 to 15 g/cm 3 ) was apparent in specular X-ray reflectivity measurements of the trilayer films when increasing the molecular weight of the sputtering gas from Ar to Kr to Xe. Significant effects on the Gilbert damping and the interfacial DMI energy were observed, with increases in the damping from 0.037(1) to 0.042(1) to 0.048(1), and reductions in the interfacial DMI from 0.47(4) mJ/m 2 to 0.45(5) mJ/m 2 to 0.39(4) mJ/m 2 . The ability to control the perpendicular magnetization and DMI strength of these materials through judicious interfacial control is a means toward magnetic devices with better stability at smaller lateral dimensions, the key to device scaling for spintronic device arrays.
{"title":"Effect of Gas Composition During Pt Sputtering on Structural and Magnetic Properties of CoFeB Thin Films","authors":"Hans T. Nembach;Justin M. Shaw;Chloe S. Taylor;Daniel B. Gopman","doi":"10.1109/LMAG.2022.3225742","DOIUrl":"10.1109/LMAG.2022.3225742","url":null,"abstract":"Ultrathin Ta/CoFeB/Pt trilayer structures are relevant to a wide range of spintronic applications, from magnetic tunnel junctions to skyrmionics devices. Controlling the perpendicular magnetic anisotropy, Gilbert damping, and Dzyaloshinskii–Moriya interaction (DMI) in the CoFeB layer is key for these applications. We examine the role of sputter gas composition during the Pt overlayer deposition of a Ta/CoFeB/Pt trilayer in Ar, Kr, and Xe working gas environments during direct current magnetron sputtering. The decreasing density of the Pt layer (from 21 to 15 g/cm\u0000<sup>3</sup>\u0000) was apparent in specular X-ray reflectivity measurements of the trilayer films when increasing the molecular weight of the sputtering gas from Ar to Kr to Xe. Significant effects on the Gilbert damping and the interfacial DMI energy were observed, with increases in the damping from 0.037(1) to 0.042(1) to 0.048(1), and reductions in the interfacial DMI from 0.47(4) mJ/m\u0000<sup>2</sup>\u0000 to 0.45(5) mJ/m\u0000<sup>2</sup>\u0000 to 0.39(4) mJ/m\u0000<sup>2</sup>\u0000. The ability to control the perpendicular magnetization and DMI strength of these materials through judicious interfacial control is a means toward magnetic devices with better stability at smaller lateral dimensions, the key to device scaling for spintronic device arrays.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10161395/pdf/nihms-1880596.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9437969","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}
Pub Date : 2022-12-05DOI: 10.1109/LMAG.2022.3226918
B. P. Alho;P. O. Ribeiro;R. S. de Oliveira;V. S. R. de Sousa;E. P. Nóbrega;B. C. Margato;J. M. N. da Silva;P. J. von Ranke
Antiferromagnetic compounds are known in the literature to present the inverse magnetocaloric effect (MCE). This effect is characterized by the negative adiabatic temperature change $Delta {T}_S$ of an antiferromagnetic material when submitted to an applied magnetic field. In an isothermal process, a positive entropy change $Delta {S}_T$ is also expected. More recently, the anisotropic character of antiferromagnetic compounds, due to spin-flop and spin-flip transitions, has been pointed out, highlighting the applicability of the antiferromagnetic compounds in a rotary magnetocaloric device. In this work, we systematically investigated a mean-field model that describes the antiferromagnetic behavior of materials in a multisublattice approach. Our model includes the nearest and next-nearest neighbor exchange interaction, the Zeeman effect, and uniaxial anisotropy energy. We investigated the effect of anisotropy on the spin-flop and spin-flip transitions on the usual and anisotropic MCE. We also demonstrated and verified an area rule for $ - {rm{Delta }}{S}_T$ versus T curves that can be used on compounds where the saturation magnetization is magnetic field dependent.
{"title":"Mean-Field Modeling of Magnetocaloric Effect of Antiferromagnetic Compounds","authors":"B. P. Alho;P. O. Ribeiro;R. S. de Oliveira;V. S. R. de Sousa;E. P. Nóbrega;B. C. Margato;J. M. N. da Silva;P. J. von Ranke","doi":"10.1109/LMAG.2022.3226918","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3226918","url":null,"abstract":"Antiferromagnetic compounds are known in the literature to present the inverse magnetocaloric effect (MCE). This effect is characterized by the negative adiabatic temperature change \u0000<inline-formula><tex-math>$Delta {T}_S$</tex-math></inline-formula>\u0000 of an antiferromagnetic material when submitted to an applied magnetic field. In an isothermal process, a positive entropy change \u0000<inline-formula><tex-math>$Delta {S}_T$</tex-math></inline-formula>\u0000 is also expected. More recently, the anisotropic character of antiferromagnetic compounds, due to spin-flop and spin-flip transitions, has been pointed out, highlighting the applicability of the antiferromagnetic compounds in a rotary magnetocaloric device. In this work, we systematically investigated a mean-field model that describes the antiferromagnetic behavior of materials in a multisublattice approach. Our model includes the nearest and next-nearest neighbor exchange interaction, the Zeeman effect, and uniaxial anisotropy energy. We investigated the effect of anisotropy on the spin-flop and spin-flip transitions on the usual and anisotropic MCE. We also demonstrated and verified an area rule for \u0000<inline-formula><tex-math>$ - {rm{Delta }}{S}_T$</tex-math></inline-formula>\u0000 versus \u0000<italic>T</i>\u0000 curves that can be used on compounds where the saturation magnetization is magnetic field dependent.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741217","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}
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