Magnetic Recording Research Articles

From megabytes to molecules: The usage of DNA computing for storage and its implications on the future

It is more important now than ever to develop more effective data storage techniques in the constantly advancing field of computers. Due to their limits in terms of durability, information density, and physical space requirements, current storage technologies, such as magnetic and optical media, are finding it difficult to keep up with the global demand for data storage, which is expected to exceed 175 trillion gigabytes by 2025. Nature’s own method of storing genetic information for a long time, deoxyribonucleic acid (DNA), provides great data density, stability, and endurance, making it a viable solution to address this issue. Through a comprehensive analysis of existing literature, this paper aims to provide a nuanced understanding of DNA computing’s current state - mainly its trajectory towards becoming a viable alternative to traditional storage methods - highlighting the history, current developments/challenges, and future prospects.

Strain-controlled switching of magnetic skyrmioniums in ultrathin nanodisks

Magnetic skyrmions and skyrmioniums have garnered significant attention due to their distinctive topologically nontrivial spin structures. Gaining a deep understanding of the magnetization dynamics of these structures and their interconversion processes is essential for fully leveraging their potential in magnetic storage technology. Here, the dynamics of strain-controlled generation and annihilation of skyrmions and skyrmioniums are investigated using phase field simulation methods. It is discovered that tensile strain can induce the transformation of a single domain into skyrmions and skyrmioniums, which can still exist stably after the strain is released. Notably, skyrmioniums demonstrate robust stability within a specific strain window of −0.2% to 0.5%. Beyond this, escalating the compressive strain magnitude induces a phase transition from skyrmioniums to skyrmions, culminating in a direct collapse to a single-domain state at a critical compressive strain of −0.8%. This study reveals that strain can effectively control a variety of topological magnetic domain structures and achieve their interconversion, providing guidance for the design of low-power, nonvolatile, multi-state spin storage devices.

Exploration of drag on the thin film of micropolar fluid flow within a permeable medium

Advances in thin film acquired many industrial applications because of their use in several products like electronic devices, magnetic recording media, LED, optical coating, etc. Additionally, thin film has an extensive role in the study of multiferroic materials and superlattices in quantum phenomena. Therefore, it is an urge to predict the importance of drag employing Darcy-Forchheimer on the thin film flow of micropolar liquid through an expanding plate embedding with a permeable medium. Moreover, the current model enriches by incorporating the impact of Soret because of the cross-diffusion process and the radiative heat. By using the appropriate transformed variables, the designed problem is distorted, and further, these sets of equations are handled numerically employing Runge-Kutta shooting technique. The computation is carried out by deploying in-house built-in function bvp4c in MATLAB. The significant operational behavior of the manipulated quantities is accessible graphically and deliberated in the discussion section. The important findings are elaborated as; the angular velocity distribution shows a greater deceleration for the increasing microrotation and the inertial drag effect. Further, the thermo-diffusion due to Soret also attenuates the concentration profile and the solutal thickness became thinner for the higher heavier species.

In-situ sub-angstrom characterization of laser-lubricant interaction in a thermo-tribological system

Laser-lubricant interaction has been a critical reliability issue in a thermo-tribological system named heat-assisted magnetic recording, one of the next generation hard disk drive solutions to increasing data storage. The lubricant response under laser irradiation and the subsequent lubricant recovery are crucial to the system’s reliability and longevity, however, they cannot be diagnosed locally and timely so far. Here, we propose a thermal scheme to in-situ characterize the mechanical laser-lubricant interaction. The nanometer-thick lubricant has a thermal barrier effect on the near-field thermal transport in the system, according to which the lubricant thickness can be determined. As demonstrations, this paper reports the first quantitative in-situ measurements of the laser-induced lubricant depletion and the subsequent reflow dynamics. The proposed scheme shows a sub-angstrom resolution (~0.2 Å) and a fast response time within seconds, rendering in-situ real-time lubricant diagnosis feasible in the practical hard disk drive products.

Advancements in CuO nanoparticle technology: synthesis, characterization of copper oxide nanoflowers

Abstract Nanostructured materials, including metal and metal oxide nanoparticles, play a crucial role in advancing diverse scientific and technological areas. Transition metal oxides such as CuO are integral to developments in fields like antibacterial treatments, solar energy conversion, sensing technologies, catalysis, magnetic storage, supercapacitors, and semiconductor devices. This research is centered on the hydrothermal synthesis of pure copper oxide nanoflowers, which are noted for their extensive surface areas. Zeta potential analysis, ultraviolet-visible spectrophotometry, field-emission scanning electron microscopy, and Fourier-transform infrared spectroscopy were some of the methods utilized to characterize these nanoparticles. The results showed that band gap energies, crystallite size, and lattice characteristics are all greatly affected by CuO. XRD results indicated a covellite monoclinic polycrystalline structure predominantly orientation with average crystallite sizes around 15.84 nm. FE-SEM imagery depicted the hierarchical, cauliflower-like structure of the CuO nanoparticles. Optical assessments revealed band gap values ranging from 2.58 eV. The findings underscore the broad potential of CuO nanoflowers across various technological applications.

Swift heavy ions induced transformations in the structural and magnetic properties of Co/Pt multilayer thin films for magnetic storage applications

The integration of CoPt nanoparticles into an insulating matrix has garnered significant attention in material science, nanotechnology, and electronic engineering, particularly for their potential use in magnetic storage media. Precise control over the size, shape, and ordering of these nanoparticles is crucial. This study investigates the impact of swift heavy ion irradiation (120 MeV Ag+9) with varying ion fluences (1 × 1013 and 3 × 1013 ions/cm2) on the structural and magnetic properties of sputter-deposited Co/Pt multilayer thin films on quartz substrates. X-ray diffraction (XRD) analysis of the pristine samples reveals the presence of an FCC-structured CoPt alloy. In contrast, films irradiated with a fluence of 1 × 1013 ions/cm2 exhibit superlattice peaks (001) and (110), indicative of L10-structured CoPt alloy, whereas films subjected to 3 × 1013 ions/cm2 retain the FCC structure. This suggests that a fluence of 1 × 1013 ions/cm2 promotes ordering, while 3 × 1013 ions/cm2 induces disordering. Selected area electron diffraction (SAED) patterns from TEM confirm these structural transitions, while SQUID magnetometry reveals an increase in coercivity at 1 × 1013 ions/cm2, followed by a reduction at 3 × 1013 ions/cm2, consistent with the observed structural changes. These results demonstrate that carefully controlled ion fluences can effectively tailor the structural and magnetic properties of Co/Pt multilayers, enhancing their suitability for advanced magnetic storage applications.

Research on magnetic fluid precise localized lubrication thrust cylindrical roller bearing with low-friction micro-vibration and high load-bearing capacity

Abstract As the magnetic field that is difficult to be distributed in the existing magnetic fluid thrust cylindrical roller bearing structure, it is more difficult for the magnetic fluid to be evenly distributed inside the bearing raceway with the axial localized lubrication, which seriously affects the engineering application of the magnetic fluid bearing. To solve the magnetic field control problem that the magnetic fluid is uneasy to be accurately localized and adsorbed, a new type of magnetic fluid thrust cylindrical roller bearing is designed in this study, which shows good characteristics of low-friction, micro-vibration and high load-bearing capacity. The seat-ring is set as an annular raceway that can be used for magnetic fluid storage and matching with the roller lubrication system, and an annular permanent magnet is designed as an external magnetic field source to be placed below the annular raceway to adsorb the magnetic fluid on the friction surface. The structure design of the axial magnetic fluid localized lubrication bearing is reasonable, which is especially suitable for precision instruments with strict operating-conditions and precision-lubrication.

Optimizing Secure Deletion in Interlaced Magnetic Recording With Move-on-Cover Approach

Optimizing Secure Deletion in Interlaced Magnetic Recording With Move-on-Cover Approach

Effect of Trivalent Ho3+ Ion Doping on Structural, Magnetic, Optical, and Electrical Properties of BiFeO3 Nanoparticles

Holmium (Ho)‐doped bismuth ferrite (BiFeO3) nanoparticles are synthesized using the citrate‐gel autocombustion method to investigate their structural, dielectric, ferroelectric, and magnetic properties. X‐Ray diffraction analysis confirms the formation of a rhombohedral perovskite structure, with crystalline size decreasing from ≈14 to 7 nm as doping levels increase. Fourier‐transform infrared spectroscopy further validates the perovskite phase, while field emission scanning electron microscopy and energy‐dispersive X‐Ray spectroscopy confirm the nanocrystalline nature and composition of the samples. X‐Ray photoelectron spectroscopy verifies the successful incorporation of Ho3+ ions into the BiFeO3 matrix. The dielectric properties show high permittivity and low dielectric losses, while magnetic hysteresis loops reveal enhanced magnetic properties, including increased saturation magnetization, remanence, coercivity, squareness ratio, Bohr magneton, and magnetocrystalline anisotropy. These findings indicate that Ho‐doped BiFeO3 nanoparticles exhibit significantly improved electric and magnetic performance, positioning them as promising candidates for applications in magnetic storage devices and sensors.

Characterization of Co-doped Ni-Mn spinel nanoferrites: A Multi-faceted evaluation of structural, optical, elastic, and magnetic properties

This study presents the synthesis and comprehensive evaluation of nanocrystalline CoxNi0.5-xMn0.5Fe2O4 (0.0 ≤ x ≤ 0.5) ferrites. Utilizing a variety of analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV–Vis) spectroscopy, field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM), we characterized the structural, optical, elastic, and magnetic properties of the synthesized nanoparticles. Our findings reveal that increasing Co content leads to a systematic increase in lattice constant from 8.33 Å to 8.39 Å and influences the crystallite size, which ranges between 10 and 15 nm as determined by XRD. Notably, the band gaps of these nanoparticles span from 2.8 to 3.6 eV, varying with Co concentration. Magnetic measurements indicate a transition from superparamagnetic-like behavior at x = 0 to enhanced saturation magnetization, remanence, and coercivity with higher Co content. The novelty of this research lies in the detailed correlation between Co substitution and the resultant changes in multiple physical properties of NiMn nanoferrite, offering potential applications in various technological fields such as magnetic storage, sensors, and biomedical applications.

Mechano-thermochemical preparation of nanostructured (FeCoNiCr/Mn)3O4 high and medium entropy oxides: Structural, microstructural, magnetic and Li-ion storage characterization

Mechano-thermochemical synthesis of (FeCoNiCrMn)3O4 high-entropy oxide (HEO) and (FeCoNiCr)3O4 medium-entropy oxide (MEO), and their structural, microstructural, magnetic, surface and electrochemical characteristics are investigated. Ball milling substantially reduces crystalline sizes of oxide precursors, causing their partial solid-state dissolution, driving the rapid formation of HEO and MEO during the subsequent thermal treatment. Nanostructured HEO prepared at 900 °C (HEO-900) comprises single-phase octahedral crystals mostly within the range 60–80 nm, while MEO-900 crystals (80–120 nm) exhibit a greater degree of agglomeration. The contribution of oxygen vacancies to total surface oxygen in MEO-900 (20.6 %) is lower than that of HEO-900 (27.6 %). HEO-900 exhibits a superior reversible Li-ion storage capacity of 1050.6 mAh/g after 300 cycles at 100 mA/g, outperforming MEO-900. However, at the higher current density of 500 mA/g, MEO-900 shows superior performance, with a reversible capacity of 432.2 mAh/g (70.3 % retention) after 750 cycles. The charge transfer resistance of fresh HEO-900 (359.0 Ω) is greater than that of MEO-900 (241.4 Ω), and the average Li-ion diffusion coefficient in HEO-900 (10-13.3 cm2 s−1) is lower than that on MEO-900 at (10-13.1 cm2 s−1) due to the greater structural complexity of the former. Full cells incorporating HEO-900 and MEO-900 anodes with LiFePO4 cathode demonstrate an energy density of 296.4 and 274.6 Wh kg−1, respectively. The saturation magnetization of HEO-900 and MEO-900 is significantly high at 33.98 and 33.80 emu/g, respectively, enabling the easy magnetic recovery of electrodes made from these compounds in spent LIBs.

Magnetized Accretion onto and Feedback from Supermassive Black Holes in Elliptical Galaxies

We present 3D magnetohydrodynamic simulations of the fueling of supermassive black holes in elliptical galaxies from a turbulent cooling medium on galactic scales, taking M87* as a typical case. We find that the mass accretion rate is increased by a factor of ∼10 compared with analogous hydrodynamic simulations. The scaling of Ṁ∼r1/2 roughly holds from ∼10 pc to ∼10−3 pc (∼10 r g) with the accretion rate through the event horizon being ∼10−2 M ⊙ yr−1. The accretion flow on scales ∼0.03–3 kpc takes the form of magnetized filaments. Within ∼30 pc, the cold gas circularizes, forming a highly magnetized (β ∼ 10−3) thick disk supported by a primarily toroidal magnetic field. The cold disk is truncated and transitions to a turbulent hot accretion flow at ∼0.3 pc (103 r g). There are strong outflows toward the poles driven by the magnetic field. The outflow energy flux increases with smaller accretor size, reaching ∼3 × 1043 erg s−1 for r in = 8 r g; this corresponds to a nearly constant energy feedback efficiency of η ∼ 0.05–0.1 independent of accretor size. The feedback energy is enough to balance the total cooling of the M87/Virgo hot halo out to ∼50 kpc. The accreted magnetic flux at small radii is similar to that in magnetically arrested disk models, consistent with the formation of a powerful jet on horizon scales in M87. Our results motivate a subgrid model for accretion in lower-resolution simulations in which the hot gas accretion rate is suppressed relative to the Bondi rate by ∼(10rg/rB)1/2 .

Toroidal mode trapping in a magnetic meta-molecule

Abstract In this paper, we establish the relationship between the eigenmodes and the scattering characteristics of a meta-molecule made of magnetic disks from the point of view of the manifestation of its toroidal response. In particular, we examine the electric and magnetic dipole contributions to the scattering cross-sections obtained in the framework of the multipole decomposition method while accounting for the polarizability and magnetization induced in the structure by the field of incoming radiation. We find out that with increasing permeability, the toroidal mode is trapped in the meta-molecule due to the presence of its magnetization part, which may have a practical perspective in gyrotropy, permittivity, and permeability sensing.

Influences of Newtonian heating and Darcy's law in micropolar fluid flow over a magnetized stretchable disk: A Bayesian analysis

A laminar two-dimensional magnetized micropolar fluid flow passed through a stretchable surface is examined. The axi-symmetric time-independent thermal flow experienced the impacts of Darcy's law, thermal conductivity, and Newtonian heating. The dimensionalized flow model is governed by similarity transformations. The resulting non-linear flow system is numerically solved through Runge-Kutta-Fehlberg (RKF-45) built in scheme. The graphics illustration of velocity and thermal fields for multiple physical parameters is presented. The numerical values at the disk surface for couple stresses, thermal rate, and shear stresses are also calculated. A Bayesian approach is used to assess the association degree amongst the under-study constraints and variables. The magnitude of the microrotational profiles is enhanced by the combined effect of micropolar parameters while an opposite effect is observed in microrotational field against magnetic and porosity parameters. The temperature field is modified through enhancing values of conjugate parameters. Moreover, such thermal field is larger for variable thermal conductivity as assumed to constant fluid property.

Dual Eu3+ and Er3+ doping in ZnO nanoporous 2D frameworks for tuning photocatalytic activity, linear and non-linear optical response

Recent days, the greater attention of research materials are focusing on the porous nano frame structure due to their distinctive properties and high photocatalytic activity. The porous defective materials revealed a significant role in numerous research fields like sensors, catalysts, energy production, magnetic memory storage, bio medical etc. In our work, pure ZnO and 4f shell shielded rare earth metals doped ZnO metal oxide nanomaterials attributed in the photocatalytic dye degradation, non-linear optical and magnetic properties. We were synthesized pure ZnO and ZnO0.1–2xEuxErxHMT0.1–2x (2x = 0.025,0.05,0.075, 0.010 wt%) nanoparticles using a straightforward hydrothermal route. The hexagonal wurtzite structure of ZnO and Eu:Er-doped ZnO (Eu:Er@ZnO) exhibited by PXRD, and the optical bandgap (Eg) range from 3.14 eV to 3.18 eV was determined by Tauc relation (αhγ)2 = 0. The porous nanoplate morphology of as-synthesized materials revealed by HR-SEM and HR-TEM techniques. All synthesized materials exposed weak ferromagnetic property nature by VSM studies. Among all the synthesized materials, the 0.0025 wt% Eu:Er@ZnO nanoparticles exhibited porous nanoplate structures capable of catalyzing the breakdown of reactive black 5 (RB5) dye, achieving a photocatalytic activity of 93.2 % after 65 min of UV light exposure. The dopant concentration significantly influenced this photocatalytic activity, with lower concentrations showing enhanced performance, particularly in acidic conditions. Moreover, all synthesized porous nano-plate materials followed pseudo-first-order kinetics. Additionally, the Z-scan technique was employed to assess the nonlinear optical properties of the synthesized materials using Q-switched nanosecond Nd laser pulses at 532 nm wavelength. The open-aperture Z-scan revealed reverse saturable absorption (RSA) in all samples. The Eu:Er@ZnO porous nano-plates exhibited promising nonlinear absorption characteristics, with a higher nonlinear absorption coefficient ranging from 5.21 to 7.84 × 10−11 m/W and a lower optical limiting threshold between 0.87 and 0.95 × 1012 W/m2.

Magnetic field simulation and analysis of superconducting magnetic separator with different magnetic matrices

Superconducting magnetic separation technology leverages strong magnetic fields to separate magnetic from non-magnetic materials, vital for industries like mining, recycling, and water treatment. This study aims to elucidate the impact of various magnetic gathering media on the magnetic field distribution within superconducting magnetic separators through detailed modeling and simulation. Using Infolytica MagNet software, we simulate the magnetic field distribution of a JS-6-102 pilot-scale superconducting magnetic separator, both without media and with different magnetic matrices, such as mesh and rod media. Our results reveal that the presence of magnetic matrices significantly alters the magnetic field distribution, enhancing magnetic induction intensity and affecting field uniformity. We demonstrate that smaller mesh sizes yield more uniform magnetic fields, while larger rod diameters increase magnetic field distortion. These findings contribute to optimizing the design and efficiency of superconducting magnetic separation systems.

Investigation of magnetocapacitance and magnetoconductivity in single-phase Y-Type hexaferrite Ba2Co2Fe12O22 nanoparticles

This research paper examines the synthesis and characterization of Y-type hexaferrite Ba2Co2Fe12O22 nanoparticles produced using the sol-gel method. The study explores their structural, magnetic, and electrical properties, confirming the successful synthesis of pure-phase hexaferrites with a hexagonal structure at an annealing temperature of 1150 °C. Morphological analysis reveals changes in nanoparticle diameter based on varying annealing temperatures. The Ba2Co2Fe12O22 nanoparticles display soft ferrimagnetism, achieving a peak saturation magnetization of 52.31 emu/g at 1150 °C, along with notable magnetocrystalline anisotropy and anisotropy field. Investigations on magnetocapacitance and magnetoconductivity under magnetic fields revealed improved performance, with high magnetocapacitance (MC%) and magnetoconductivity (MσAC%) percentages of 24 % and 21 %, respectively. This suggests the potential utility of these nanoparticles in applications such as permanent magnets, magnetic recording media, and spintronic devices.

Additively manufactured FeCoNiSi0.2 alloy with excellent soft magnetic and mechanical properties through texture engineering

High-entropy alloys are widely used as structural materials and hold potential as functional materials. This study aims to develop a soft magnetic medium entropy alloy FeCoNiSi0.2 (Si0.2 MEA) with excellent soft magnetic properties and higher ductility using additive manufacturing technology. The microstructure of Si0.2 MEA is characterized by texture and large grains, with a single FCC phase structure. The texture strength of MEA initially increases and then decreases with the addition of Si, with Si0.1 MEA exhibiting the strongest fiber texture. Among the four FeCoNiSix MEAs, Si0.2 MEA demonstrates the best tensile properties (i.e. δ ∼39 %, σ0.2–287 MPA, σb∼551 MPa). The correlation generalized stacking fault energy calculation model indicates that Si0.2 MEA has the lowest generalized stacking fault energy (∼7 mJ/m2), suggesting superior ductility. The synergistic effect of texture and large grains promotes the formation of a magnetization “easy axis”, which makes Si0.2 MEA exhibit the best soft magnetic properties (Ms:150emu/g, Hc:1.04Oe). These results provide a new paradigm for developing laser additively manufactured soft magnetic medium entropy alloy.

Exploring spin polarization of heavy quarks in magnetic fields and hot medium

Exploring spin polarization of heavy quarks in magnetic fields and hot medium

Experimental study on surface optimization of dosage in magnetic coagulation process for enhancing primary treatment of urban sewage

This work aims to investigate the minimum dosage required to achieve optimal removal of carbon, nitrogen, and phosphorus in the Chemical Enhanced Primary Treatment (CEPT) process using magnetic coagulation technology. A response surface methodology was adopted to generate multiple regression models to optimize the dosages of three types of coagulation, i.e., polyaluminum chloride (PAC), polyacrylamide (PAM), and magnetic medium Fe3O4 particles (MP), based on the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and total phosphorus (TP). The results showed that the regression models could predict results well with actual engineering results. Compared to the traditional coagulation process, the synergistic enhancement of PAC+PAM+MP in the CEPT process significantly improved the treatment effects. Based on the COD removal rates, PAC performed better than MP, followed by PAM; likewise, for the NH3-N and TP removal rates, PAC outperformed PAM, followed by MP. The optimized PAC, PAM, and MP dosages were 135.87, 1.51, and 108.36 mg/L, respectively, reaching 92.27 % COD, 71.98 % NH3-N, and 91.33 % TP removal rates with less than 5 % errors compared to the experimental verification results. These optimization models offer a practical and cost-saving reference for enhancing the primary treatment effect on carbon, nitrogen, and phosphorus removal using PAC+PAM+MP.