Article
Chemistry, Multidisciplinary
Seongkwon Jeong, Jaejin Lee
Summary: This study proposes a modulation decoding method based on the K-means algorithm to improve decoding capabilities in bit-patterned media recording systems. Increasing the areal density makes it more difficult to detect data due to the influence of intersymbol interference (ISI) and intertrack interference (ITI), but modulation coding can prevent severe ISI and ITI caused by specific data patterns.
APPLIED SCIENCES-BASEL
(2022)
Article
Nanoscience & Nanotechnology
S. Sokjabok, M. Mattayakan, C. Buajong, S. Koonkarnkhai, P. Kovintavewat, C. Warisarn
Summary: The reduction in track width of ultra-high density magnetic recording leads to an increase in areal density, but also brings about severe inter-symbol interference and inter-track interference. To address these issues, a single-reader/two-track reading technique and constrained coding schemes are proposed, showing superior performance in mitigating ISI and ITI effects compared to conventional systems.
Article
Chemistry, Multidisciplinary
Thien An Nguyen, Jaejin Lee
Summary: Ultra-high density data storage, specifically using bit-pattern media recording (BPMR), is crucial due to the increasing volumes of data. A neural network model for noise prediction has been proposed to improve the performance of serial detection, resulting in approximately 1 dB gain in bit error rate (BER) compared to the model with a feedback line.
APPLIED SCIENCES-BASEL
(2021)
Article
Computer Science, Information Systems
Thien An Nguyen, Jaejin Lee
Summary: This article examines a new distribution of bit-patterned media recording called staggered BPMR. By dividing the interference into three parts and using three one-dimensional detectors, the proposed model improves the detection performance of the main data. Simulation results demonstrate that this model outperforms previous studies.
Article
Chemistry, Physical
Li-Jie Liaw, Po-Chun Chang, Po-Wei Chen, Zi-Qi Liu, Shi-Yu Liu, Chun-Tse Hsieh, Alltrin Dhanarajgopal, Ming-Yau Chern, Fang-Yuh Lo, Wen-Chin Lin
Summary: In this study, magnesium (Mg) was added to the palladium (Pd)/ferromagnetic multilayers to enhance and stabilize the effects of hydrogenation. It was found that Mg could absorb hydrogen (H) at room temperature under 1 bar H-2 pressure with the help of a Pd-capping layer. The hydrogenation effect increased the magnetic coercivity and surface roughness, and transformed the crystalline structure from pure Mg to magnesium hydride (MgH2).
SURFACES AND INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Thien An Nguyen, Jaejin Lee
Summary: Bit-patterned media recording (BPMR) is a promising technology for increasing the areal density (AD) of magnetic data storage systems. In this study, the maximum a posteriori (MAP) algorithm is proposed to improve the serial detection method and address the issues of 2D interference and track mis-registration (TMR) in BPMR.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Electrical & Electronic
Seongkwon Jeong, Jaejin Lee
Summary: In this study, a bit-flipping scheme using the K-means algorithm for bit-patterned media recording (BPMR) system is proposed to increase the areal density of hard disk drives. The scheme reduces the distance between islands storing 1 bit and utilizes neighboring information to improve performance.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Chemistry, Physical
Yuhui Wang, Ying Zheng, Ziyi Zhong, Zijun Wang, Yongfeng Liang, Pingping Wu
Summary: The magnetic properties of a core-shell type exchange coupled composite structure were studied using micromagnetic simulation. Switching loops with magnetic domain structure evolution were demonstrated and a switching type diagram was constructed. The effects of switching type and composite structure on coercivity and remanent magnetization were predicted and discussed. The core-shell type FePt/Fe composite structure film was found to have a significant advantage in designing high-density storage devices at the nanoscale.
Article
Chemistry, Multidisciplinary
Gyuyeol Kong, Minchae Jung
Summary: This paper proposes a tabu search aided multi-track detection scheme for bit patterned magnetic recording. The proposed scheme adopts a simplified multi-track detector with a two-dimensional generalized partial response target, uses a priori information, and employs a reliability test and a tabu search detector. The proposed scheme processes signals in three stages, and achieves better performance compared to conventional schemes.
APPLIED SCIENCES-BASEL
(2022)
Article
Chemistry, Multidisciplinary
Seongkwon Jeong, Jaejin Lee
Summary: This study investigates the electronic structure and magnetic properties of potential two-dimensional material MnPS3 using density functional theory. The results reveal its semiconductor nature and antiferromagnetic properties, providing a theoretical basis for its applications in electronic and magnetic devices.
APPLIED SCIENCES-BASEL
(2022)
Article
Chemistry, Analytical
Pirat Khunkitti, Naruemon Wannawong, Chavakon Jongjaihan, Apirat Siritaratiwat, Anan Kruesubthaworn, Arkom Kaewrawang
Summary: This study introduces exchange-coupled composite bit-patterned media (ECC-BPM) combined with microwave-assisted magnetic recording (MAMR) to enhance the writeability of magnetic media at a recording density of 4 Tb/in^2. By evaluating the suitable microwave field frequency and exchange coupling values between magnetic dots in the proposed media, significant reductions in switching field were achieved compared to conventional media, further decreased by utilizing MAMR technology.
Article
Nanoscience & Nanotechnology
Abdullah Al Shafe, Mohammad Delower Hossain, Robert A. Mayanovic, Vladimir Roddatis, Mourad Benamara
Summary: A series of bimagnetic heterostructured nanocrystals with an antiferromagnetic NiO core and a ferrimagnetic MnxNi1-xO and/or Mn3O4 island nanophase overgrowth were successfully synthesized under varying aqueous solution pH conditions. The magnetic properties of these nanocrystals, including coercivity and exchange bias field, were found to systematically vary with the pH used for synthesis. These heterostructured nanocrystals show potential applications in magnetic devices, biomedical fields, and other areas.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
J. T. Liu, X. L. Xu, G. N. Feng, X. Y. Yang, D. Zhao, M. G. Zuo, C. Y. Liu, C. Feng, S. Liu, B. H. Li, G. H. Yu
Summary: This study demonstrates a promising candidate for next-generation magnetic code disk materials used in high-accuracy magnetic rotary encoders, with a FeCoCr-based film exhibiting high coercivity and sufficient remanent magnetization. The high coercivity is attributed to the domain-wall pinning effect induced by factors such as grain refinement, heterogeneous phase generation, and composition fluctuation of modulated phases. The high remanent magnetization is ascribed to the higher relative content of Fe2Ta phases in the film.
Article
Chemistry, Multidisciplinary
Thien An Nguyen, Jaejin Lee
Summary: Bit-patterned media recording (BPMR) is proposed as a candidate solution for addressing superparamagnetism issues in magnetic data storage. This study focuses on reducing the distance between magnetic islands in BPMR to increase the areal density, while also addressing the increased two-dimensional interference. A new estimator based on the 2D Viterbi algorithm (VA) with reduced states is proposed to predict interference from neighboring tracks. Simulation results demonstrate the superiority of this model compared to previous models.
APPLIED SCIENCES-BASEL
(2022)
Article
Materials Science, Multidisciplinary
Thomas A. Schefer, David L. Cortie, Mikhail Kostylev
Summary: By using ferromagnetic resonance (FMR) spectroscopy, we have found that the FMR peak in Pd/[Co/Pd](30)/Pd multilayer thin films shifts in the presence of hydrogen gas, with a larger shift observed for samples with thicker Pd layers. We have also observed a correlation between the linewidth and the Pd layer thickness, which can be explained by the presence of spin pumping.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Gerald Q. Yan, Senlei Li, Hanyi Lu, Mengqi Huang, Yuxuan Xiao, Luke Wernert, Jeffrey A. Brock, Eric E. Fullerton, Hua Chen, Hailong Wang, Chunhui Rita Du
Summary: This paper reports on the nanoscale imaging of spin-orbit-torque-induced deterministic magnetic switching and chiral spin rotation in non-collinear antiferromagnet Mn3Sn films using nitrogen-vacancy (NV) centers. Direct evidence of the off-resonance dipole-dipole coupling between the spin dynamics in Mn3Sn and proximate NV centers is also demonstrated by NV relaxometry measurements.
ADVANCED MATERIALS
(2022)
Article
Multidisciplinary Sciences
Youngjun Ahn, Mathew J. Cherukara, Zhonghou Cai, Michael Bartlein, Tao Zhou, Anthony DiChiara, Donald A. Walko, Martin Holt, Eric E. Fullerton, Paul G. Evans, Haidan Wen
Summary: Ultrafast first-order phase transitions show distinct transition pathways and properties, accompanied by nanoscale structural dynamics. Understanding these transitions is important for applications involving fast switching of properties.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Multidisciplinary Sciences
G. Li, R. Medapalli, J. H. Mentink, R. V. Mikhaylovskiy, T. G. H. Blank, S. K. K. Patel, A. K. Zvezdin, Th. Rasing, E. E. Fullerton, A. V. Kimel
Summary: Understanding the rapid development of long-range order through short-range interactions is an intriguing topic in condensed matter physics. Researchers used double-pump THz emission spectroscopy to study the transition from antiferromagnetic to ferromagnetic state in FeRh, revealing a latency period between pump excitation and THz radiation emission.
NATURE COMMUNICATIONS
(2022)
Article
Nanoscience & Nanotechnology
C. Walker, M. Parkes, C. Olsson, D. Keavney, E. E. Fullerton, K. Chesnel
Summary: In this study, we measured the local magneto-transport signal in micro-structured [Co/Pd]IrMn thin multilayers with an out-of-plane magnetic field and found that the positioning and geometry of the contacts significantly affect the signal. We also observed a distortion in the signal shape due to the presence of a window.
Article
Geochemistry & Geophysics
Fatima Meite, Mustapha Abdelmoula, Patrick Billard, Thomas Hauet, Asfaw Zegeye
Summary: This study investigates the changes in Pb-bearing ferrihydrite during bioreduction, finding that Pb doping leads to a decrease in reduction rate and extent, as well as influencing the formation of secondary minerals. Through redox cycling, Pb significantly sorbs onto the minerals that are formed.
Article
Multidisciplinary Sciences
Diego Turenne, Alexander Yaroslavtsev, Xiaocui Wang, Vivek Unikandanuni, Igor Vaskivskyi, Michael Schneider, Emmanuelle Jal, Robert Carley, Guiseppe Mercurio, Rafael Gort, Naman Agarwal, Benjamin Van Kuiken, Laurent Mercadier, Justine Schlappa, Loic Le Guyader, Natalia Gerasimova, Martin Teichmann, David Lomidze, Andrea Castoldi, Dimitri Potorochin, Deepak Mukkattukavil, Jeffrey Brock, Nanna Zhou Hagstrom, Alexander H. Reid, Xiaozhe Shen, Xijie J. Wang, Pablo Maldonado, Yaroslav Kvashnin, Karel Carva, Jian Wang, Yukiko K. Takahashi, Eric E. Fullerton, Stefan Eisebitt, Peter M. Oppeneer, Serguei Molodtsov, Andreas Scherz, Stefano Bonetti, Ezio Iacocca, Hermann A. Durr
Summary: Magnetic nanoparticles, such as FePt in the L1(0) phase, are crucial for current data storage technology. By studying the existence of spin-wave solitons in FePt nanoparticles, potential platforms for developing novel miniature devices can be explored.
Article
Physics, Multidisciplinary
Jiaruo Li, Oleg Yu Gorobtsov, Sheena K. K. Patel, Nelson Hua, Benjamin Gregory, Anatoly G. Shabalin, Stjepan Hrkac, James Wingert, Devin Cela, James M. Glownia, Matthieu Chollet, Diling Zhu, Rajasekhar Medapalli, Eric E. Fullerton, Oleg G. Shpyrko, Andrej Singer
Summary: This study demonstrates experimentally the role phonons play in SDW formation after an SDW-quench by femtosecond laser pulses. The temperature-dependent SDW period in thin films is quantized, allowing for precise tracking of the out-of-equilibrium formation path of the SDW.
COMMUNICATIONS PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Axel Hoffmann, Shriram Ramanathan, Julie Grollier, Andrew D. Kent, Marcelo J. Rozenberg, Ivan K. Schuller, Oleg G. Shpyrko, Robert C. Dynes, Yeshaiahu Fainman, Alex Frano, Eric E. Fullerton, Giulia Galli, Vitaliy Lomakin, Shyue Ping Ong, Amanda K. Petford-Long, Jonathan A. Schuller, Mark D. Stiles, Yayoi Takamura, Yimei Zhu
Summary: Neuromorphic computing approaches are becoming increasingly important for efficiently processing large amounts of data. Quantum materials offer unique attributes that can enable new energy-efficient device concepts at the hardware level. This Perspective discusses select examples of these approaches and provides an outlook on the current opportunities and challenges for assembling quantum-material-based devices into larger complex network systems.
Article
Instruments & Instrumentation
T. A. Assefa, M. H. Seaberg, A. H. Reid, L. Shen, V Esposito, G. L. Dakovski, W. Schlotter, B. Holladay, R. Streubel, S. A. Montoya, P. Hart, K. Nakahara, S. Moeller, S. D. Kevan, P. Fischer, E. E. Fullerton, W. Colocho, A. Lutman, F-J Decker, S. K. Sinha, S. Roy, E. Blackburn, J. J. Turner
Summary: The development of new modes at x-ray free electron lasers has led to innovative methods for studying fluctuations at different energies and timescales. A pair of advanced instruments were used to conduct experiments on quantum materials, including testing the proof-of-principle of resonant magnetic scattering using ultrafast pulses and studying fluctuations using a fast area detector. Various diagnostics for single-shot contrast measurements were also employed to normalize data and calibrate pulse amplitude ratios, which are crucial for the study of material fluctuations. The results obtained with the instrument demonstrate higher momentum resolution.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Materials Science, Multidisciplinary
Nelson Hua, Jianheng Li, Stjepan B. Hrkac, Andi Barbour, Wen Hu, Claudio Mazzoli, Stuart Wilkins, Roopali Kukreja, Eric E. Fullerton, Oleg G. Shpyrko
Summary: We studied charge-orbital fluctuations in the insulating state of magnetite using resonant elastic x-ray scattering and x-ray photon correlation spectroscopy. Our results revealed the dynamics of the iron 3d and oxygen 2p orbital domains, showing a decoupling of the orbital correlation lengths between the oxygen ligands and site-specific iron 3d states. We also observed charge-orbital domain fluctuations at the iron t(2g) orbital sites of trimeron chains.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Nan Tang, W. L. N. C. Liyanage, Sergio A. Montoya, Sheena Patel, Lizabeth J. Quigley, Alexander J. Grutter, Michael R. Fitzsimmons, Sunil Sinha, Julie A. Borchers, Eric E. Fullerton, Lisa DeBeer-Schmitt, Dustin A. Gilbert
Summary: Magnetic skyrmions exhibit unique behaviors arising from their topological protection, including well-defined, 3D dynamic modes at microwave frequencies. Spin waves ejected into the interstitial regions between skyrmions create a magnetic turbulent sea. However, spin-wave interference can result in ordered structures due to the well-defined length scale and ordered lattice. This study captures the dynamics in hybrid skyrmions using small-angle neutron scattering and identifies a dynamic spin-wave fractal structure.
ADVANCED MATERIALS
(2023)
Article
Physics, Applied
Biswajit Sahoo, Alex Frano, Eric. E. Fullerton
Summary: Many 5d transition metal oxides have a unique electronic structure dominated by only 5d electrons with strong spin-orbit coupling. IrO2 is the simplest of these oxides and exhibits a Dirac nodal line semi-metal behavior. By using spin-torque ferromagnetic resonance experiments, we demonstrate the large charge-to-spin conversion in thin films of optimized IrO2 and determine that the spin Hall angle is approximately 8 times larger than that of Pt.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
W. L. N. C. Liyanage, Nan Tang, Lizabeth Quigley, Julie A. Borchers, Alexander J. Grutter, Brian B. Maranville, Sunil K. Sinha, Nicolas Reyren, Sergio A. Montoya, Eric E. Fullerton, Lisa DeBeer-Schmitt, Dustin A. Gilbert
Summary: This paper uses neutron scattering and polarized neutron reflectometry to determine the 3D structure of hybrid skyrmions. The structure of these skyrmions, which includes a combination of Neel-like and Bloch-like components, contributes to their notable stability.
Article
Materials Science, Multidisciplinary
James Wampler, Nelson Hua, Roopali Kukreja, Juan Gabriel Ramirez, Ali C. Basaran, Eric E. Fullerton, Oleg Shpyrko, Ivan K. Schuller
Summary: Low-field microwave absorption techniques are sensitive and nondestructive methods for probing electric and magnetic properties of solids. A technique involving magnetic hysteresis loops and magnetoresistance measurements is presented to investigate the electric and magnetic properties of a sample with complex electromagnetic responses. The technique can be applied to analyze MFMMS signals of magnetite, providing insights into its electric, magnetic, and structural phase transitions.
Article
Materials Science, Multidisciplinary
Nanna Zhou Hagstrom, Rahul Jangid, Meera Madhavi, Diego Turenne, Jeffrey A. Brock, Erik S. Lamb, Boyan Stoychev, Justine Schlappa, Natalia Gerasimova, Benjamin Van Kuiken, Rafael Gort, Laurent Mercadier, Loic Le Guyader, Andrey Samartsev, Andreas Scherz, Giuseppe Mercurio, Hermann A. Durr, Alexander H. Reid, Monika Arora, Hans T. Nembach, Justin M. Shaw, Emmanuelle Jal, Eric E. Fullerton, Mark W. Keller, Roopali Kukreja, Stefano Bonetti, Thomas J. Silva, Ezio Iacocca
Summary: The study reveals that the ultrafast response of magnetic domain patterns is related to spatial features, and far-from-equilibrium magnetization dynamics offer alternative pathways for spatiotemporal manipulation of magnetism.
