IEEE Magnetics Letters最新文献

{"title":"Antiferromagnetism in Two-Dimensional, 1T-Phase Iridium Oxide","authors":"Charlie Jindrich;Qi Shao;Antonio Ruotolo","doi":"10.1109/LMAG.2024.3350438","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3350438","url":null,"abstract":"Theoretical studies show that metastable phases of nonmagnetic oxides could exhibit magnetic order when synthesized in two-dimensional (2-D) atomic crystals. In this letter, we report experimental evidence of a nontrivial antiferromagnetic behavior in a 2-D, metastable phase of iridium oxide in which iridium forms a triangular lattice. We compare the magnetic behavior of the crystals in the morphology of 2-D nanosheets with that of the same crystals in the morphology of nanoparticles. At low temperatures, the magnetic moment of nanosheets exceeds that of the nanoparticles while coercivity and remanence collapse, suggesting a transition to an antiferromagnetic phase. Morphology at the nanoscale seems to play a significant role in the magnetic behavior of oxide semiconductors.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139694981","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 Field-Induced Phase Transition and Weak Ferromagnetism in Nonsuperconducting Optimally Doped PrBCO Cuprate","authors":"Mahieddine Lahoubi;Shengli Pu;Weinan Liu;Zhe Yang","doi":"10.1109/LMAG.2024.3350428","DOIUrl":"10.1109/LMAG.2024.3350428","url":null,"abstract":"In this letter, we report anomalous magnetic properties in high dc magnetic fields \u0000<italic>H</i>\u0000 up to 11 and 16 T from 1.35 up to 20 K on PrBa\u0000₂\u0000Cu\u0000₃\u0000O\u0000_6.95\u0000 (PrBCO\u0000_6.95\u0000) cuprate ceramic. Significant magnetic-field effects are revealed in the derivative of the magnetization \u0000<italic>M</i>\u0000(\u0000<italic>T</i>\u0000) versus \u0000<italic>T</i>\u0000 using two sets of values of \u0000<italic>H</i>\u0000 selected in the range of 2.5–9.5 T. Anomalies are observed at the low-critical point \u0000<italic>T</i>\u0000_cr\u0000 = 4–5 K, in the region of the spin reorientation phase transition temperature \u0000<italic>T</i>\u0000₂\u0000 = 10.5 K, and around the Néel temperature of the antiferromagnetic ordering of the Pr\u0000³⁺\u0000 sublattice \u0000<italic>T</i>\u0000_N\u0000 = 14 K. Using Arrott plot analysis, we identified weak field-induced phase transitions at two critical fields, \u0000<italic>H</i>\u0000_cr1\u0000(\u0000<italic>T</i>\u0000) ∼ 3.3 T and \u0000<italic>H</i>\u0000_cr2\u0000(\u0000<italic>T</i>\u0000) ∼ 7.5 T, whose associated transition lines exhibit an almost temperature-independent behavior in the range 1.35 K-\u0000<italic>T</i>\u0000₂\u0000, and seem to vanish in the vicinity of \u0000<italic>T</i>\u0000_N\u0000. When \u0000<italic>T</i>\u0000 decreases from 20 K, an increase occurs in the derivative of the magnetization \u0000<italic>M</i>\u0000(\u0000<italic>H</i>\u0000) versus \u0000<italic>H</i>\u0000 for 0.5 T < \u0000<italic>H</i>\u0000 < 1 T, as well as in the differential susceptibility \u0000<italic>χ</i>\u0000_d\u0000(\u0000<italic>T</i>\u0000) versus \u0000<italic>T</i>\u0000 where a shape change occurs when crossing \u0000<italic>T</i>\u0000_cr\u0000. The spontaneous magnetization \u0000<italic>M</i>\u0000_S\u0000(\u0000<italic>T</i>\u0000), which was deduced by extrapolation to zero-field from the field-linear regime up to 2 T, shows an inverse variation with \u0000<italic>T</i>\u0000 and a shape change when crossing \u0000<italic>T</i>\u0000_N\u0000 and \u0000<italic>T</i>\u0000₂\u0000. These features, which are taken as evidence for an additional weak ferromagnetic-like component that survives above \u0000<italic>T</i>\u0000_N\u0000, result from the significant role of the Pr-Cu(2) magnetic coupling.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139950929","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":"Microstructure Evolution and First-Order Reversal Curve Analysis of the Interphase Coupling in SmCo Thick Film","authors":"Oksana Koplak;Federico Maspero;Alejandro Plaza;Andrea Del Giacco;Maria Cocconcelli;Riccardo Bertacco","doi":"10.1109/LMAG.2023.3344026","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3344026","url":null,"abstract":"Thick SmCo films of 500 nm thickness were deposited by radio frequency sputtering in W/SmCo/W structures on a Si substrate. After annealing at 650–750 °C, the as-grown soft amorphous structure transforms into a mixture of crystalline Sm\u0000₂\u0000Co\u0000₁₇\u0000 and SmCo\u0000₅\u0000 hard magnetic phases. Annealing at 650 °C leads to film crystallization with an average grain size of 64 nm, coercivity of 0.5 T, and remanence magnetization of about 0.5 T for a maximum applied field of 2 T. The remanence magnetization decreases by 20% upon annealing at 750 °C, whereas the average crystalline size and coercivity increase up to 73 nm and 1.1 T, respectively. Series of the first-order reversal curves recorded in the samples that were annealed at 650 °C and 750 °C demonstrate redistribution of the switching fields between the softer (Sm\u0000₂\u0000Co\u0000₁₇₎\u0000 and harder (SmCo\u0000₅\u0000) phases, depending on the strength of interphase interaction. Overall, the higher remanence and sizable coercivity of films annealed at 650 °C make them good candidates for the fabrication of micromagnets to be integrated in microelectromechanical systems.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139654699","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":"Spin Transport and Magnetic Proximity Effect in CoFeB/Normal Metal/Pt Trilayers","authors":"Simon Häuser;Matthias R. Schweizer;Sascha Keller;Andres Conca;Moritz Hofherr;Evangelos Papaioannou;Benjamin Stadtmüller;Burkard Hillebrands;Martin Aeschlimann;Mathias Weiler","doi":"10.1109/LMAG.2023.3340122","DOIUrl":"10.1109/LMAG.2023.3340122","url":null,"abstract":"We present a study of the damping and spin pumping properties of CoFeB/X/Pt systems with \u0000<inline-formula><tex-math>$rm X=Al,Cr$</tex-math></inline-formula>\u0000, and \u0000<inline-formula><tex-math>$rm Ta$</tex-math></inline-formula>\u0000. We show that the total damping of the CoFeB/Pt systems is strongly reduced when an interlayer is introduced independently of the material. Using a model that considers spin relaxation, we identify the origin of this contribution in the magnetically polarized Pt formed by the magnetic proximity effect (MPE), which is suppressed by the introduction of the interlayer. The induced ferromagnetic order in the Pt layer is confirmed by element-sensitive transverse magneto-optical Kerr spectroscopy at the M\u0000<inline-formula><tex-math>$_{2,3}$</tex-math></inline-formula>\u0000 and N\u0000<inline-formula><tex-math>$_{7}$</tex-math></inline-formula>\u0000 absorption edges. We discuss the impact of the MPE on parameter extraction in the spin transport model.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139369413","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":"A Numerical Method to Determine Demagnetization Factors of Stadium-Shaped Nanoislands for Artificial Spin Ices","authors":"Victoria Martinez;Ezio Iacocca","doi":"10.1109/LMAG.2023.3334670","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3334670","url":null,"abstract":"The shape of nanoislands gives rise to a demagnetizing field that is primarily responsible for the orientation of the magnetization along an axis. In the context of magnetization dynamics, the demagnetization (demag) field also determines the resonant frequencies captured by Kittel's equations. Analytically, we require demag factors that can be obtained exactly for a few geometries, including ellipsoids and prisms. However, analytical expressions are not available for other shapes, limiting the use of Kittel's equation as a predictive model. Here, we present a method to obtain the demag factors from micromagnetic simulations with good accuracy. Similar to other experiments, ferromagnetic resonance was obtained, but we use orthogonal field conditions to fit Kittel's equation unambiguously and obtain the demag factors with good accuracy. This method will be useful to determine demag factors under the ellipsoidal approximation for stadium-shaped nanoislands used in artificial spin ices and thus lead to a better prediction in their ferromagnetic resonance and band structures.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138822044","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":"A High-Sensitivity Composite Probe Capable of Simultaneously Measuring Electric- and Magnetic-Field Components","authors":"Lei Wang;Duan Nie;Liye Cheng;Hongyue Wang","doi":"10.1109/LMAG.2023.3324517","DOIUrl":"10.1109/LMAG.2023.3324517","url":null,"abstract":"This letter presents a high-sensitivity composite probe capable of simultaneously measuring electric- and magnetic-field components. The composite probe contains a U-shaped loop, two parasitic long loops, and a pair of strip lines as a transmission part. First, the U-shaped loop is designed to test both electric and magnetic fields. Second, two parasitic long loops are placed at both sides of the U-shaped loop to increase the sensitivity. Third, to characterize and calibrate the probe, a standard microstrip line is manufactured and used. Finally, the developed probe is printed and tested to prove the feasibility of the design. The tested results indicate that the probe can not only simultaneously test electric and magnetic fields, but also have a wider working bandwidth and higher sensitivity.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136306060","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":"Materials Informatics for the Development and Discovery of Future Magnetic Materials","authors":"Ryotaro Okabe;Mingda Li;Yuma Iwasaki;Nicolas Regnault;Claudia Felser;Masafumi Shirai;Alexander Kovacs;Thomas Schrefl;Atsufumi Hirohata","doi":"10.1109/LMAG.2023.3320888","DOIUrl":"10.1109/LMAG.2023.3320888","url":null,"abstract":"This letter summarizes the recent development of magnetic materials search using artificial intelligence (AI) and machine learning (ML) and briefly introduces ML and AI approaches to materials discovery. The authors offer a flowchart to aid the selection of relevant approaches for their material search. This letter also covers the authors' recent research activities in magnetism and quantum materials, including topological materials, Heusler alloys, interfaces, and permanent magnets. This overview is based on a recent symposium at IEEE Intermag 2023.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10268090","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135839038","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":"Fabrication and Characterization CoZrO Films Deposited by Facing Targets Reactive Sputtering for Micromagnetic Inductors","authors":"Honami Nitta;Yota Takamura;Tadayuki Kaneko;Shigeki Nakagawa","doi":"10.1109/LMAG.2023.3320495","DOIUrl":"10.1109/LMAG.2023.3320495","url":null,"abstract":"In recent years, there has been a strong demand for soft magnetic films suitable for high-frequency micromagnetic devices as power electronics circuits to operate at higher frequencies. Specifically, there is a need for magnetic thin films with ferromagnetic resonance frequencies (\u0000<italic>f</i>\u0000_r\u0000) in the range of several gigahertz. Nanogranular CoZrO thin films have emerged as promising candidates due to their high \u0000<italic>f</i>\u0000_r\u0000 and high electrical resistivity. We fabricated CoZrO thin films using facing targets reactive sputtering with oxygen as the reactive gas. As the oxygen partial pressure ratio (\u0000<italic>P</i>\u0000_O2\u0000) was gradually increased up to 0.8%, clear uniaxial magnetic anisotropy appeared, leading to improved soft magnetic properties. At a \u0000<italic>P</i>\u0000_O2\u0000 of 0.8%, the film exhibited the most superior soft magnetic properties. With further increase in \u0000<italic>P</i>\u0000_O2\u0000, magnetic loops implying a stripe magnetic-domain structure were obtained. In this \u0000<italic>P</i>\u0000_O2\u0000 range, phase separation was observed, along with a sharp increase in electrical resistivity. \u0000<italic>f</i>\u0000_r\u0000 of the CoZrO film formed at \u0000<italic>P</i>\u0000_O2\u0000 = 0.8% was determined to be 3.2 GHz from high-frequency permeability measurement. We have confirmed the effectiveness of facing targets’ reactive sputtering in preparing CoZrO films with excellent soft magnetic properties.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135838519","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":"Increasing Flips per Second and Speed of p-Computers by Using Dilute Magnetic Semiconductors","authors":"Rahnuma Rahman;Supriyo Bandyopadhyay","doi":"10.1109/LMAG.2023.3319992","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3319992","url":null,"abstract":"Probabilistic computing with binary stochastic neurons (BSNs) implemented with low-barrier magnets (LBMs) or zero-energy barrier nanoscale ferromagnets possessing in-plane magnetic anisotropy has emerged as an efficient paradigm for solving computationally hard problems. The fluctuating magnetization of an LBM at room temperature encodes a p-bit, which is the building block of a BSN. Its drawback, however, is that the dynamics of common (transition metal) ferromagnets are relatively slow, and, hence, the number of uncorrelated p-bits that can be generated per second—the so-called “flips per second” (\u0000<italic>fps</i>\u0000)—is insufficient, leading to slow computational speed in autonomous coprocessing with p-computers. Here, we show that a simple way to increase \u0000<italic>fps</i>\u0000 in LBMs is to replace commonly used ferromagnets (e.g., Co, Fe, and Ni), which have large saturation magnetization \u0000<italic>M_s</i>\u0000, with a dilute magnetic semiconductor, such as GaMnAs with much smaller saturation magnetization. The smaller \u0000<italic>M_s</i>\u0000 reduces any residual energy barrier within an LBM and increases the \u0000<italic>fps</i>\u0000 significantly. It also offers other benefits, such as reduced dipole coupling between neighbors, resulting in larger density of uncorrelated p-bits for more processing power, and reduced device-to-device variation. All this provides a way to realize the hardware acceleration and energy efficiency promise of p-computers.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763009","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":"Investigation of the Soft-Magnetic Properties of CoZrTaB Laminated Cores by Dielectric Layer Tuning","authors":"Guannan Wei;Rajasree Das;Daniel Lordan;Marek Lorenc;Barry Clark;David P. F. Hurley;Mike Hayes;Cian O'Mathuna;Ranajit Sai;Paul McCloskey","doi":"10.1109/LMAG.2023.3319289","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3319289","url":null,"abstract":"Soft magnetic properties of thin films for use as a core material are critical for the realization of future miniaturized electromagnetic devices operating at frequencies of tens or hundreds of megahertz. Laminated stacks consisting of alternate thin layers of magnetic material and dielectric material are widely used to suppress eddy current losses that dominate, especially at a higher frequency of operation. Thus, identifying a suitable dielectric layer, its optimum thickness, and the understanding of its effect on the performance of the laminated core is important. In this letter, six different CoZrTaB (CZTB) laminated cores are reported, featuring a variety of dielectric materials (AlN, SiN, Al\u0000₂\u0000O\u0000₃\u0000, and oxide CZTB) and/or dielectric thickness (5, 15, and 50 nm). This study shows that stacks with different dielectric materials have a varied residual stress that plays an important role in inducing magnetic anisotropy, thus affecting the permeability. CZTB stacks with oxide CZTB dielectric show the best combination of high permeability, low coercivity, and low losses at high frequency.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763016","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}