In the heat-assisted magnetic recording (HAMR) process, the transition jitter is known to depend on the grain size as well as the heat spot thermal gradient. We find that the jitter also depends on the Voronoi grain size distribution, as well as exhibiting a surprising nonlinear dependence on reader width. By combining the noise due to these dependencies we used an analytical formulation to estimate

This letter presents a novel speed sensor based on motion-induced eddy currents in conductive moving parts. The magnetic yoke is an E-shaped ferrite core. The excitation coil is on the center leg of the E-core, and two antiserially connected pick-up coils are on the side legs. Solid iron and aluminum materials are used for the moving part in the simulations and in the measurements. Two-dimensional

In a bit-patterned media recording (BPMR) system, reducing the spacing between adjacent bit islands in the down- and cross-track directions increases areal density; however, two-dimensional (2-D) interference comprising intersymbol and intertrack interferences degrades the system performance. To mitigate error patterns that increase the 2-D interference in BPMRs, 2-D modulation coding schemes have

We report on magnetic properties of Fe–Ni–Ti alloys after severe plastic deformation (SPD) by high-pressure torsion (HPT) and low-temperature annealing. SPD and low-temperature annealing considerably change the magnetization behavior. The main magnetic and structural characteristics of bulk and HPT materials were determined. The addition of small amounts of Ti and annealing at 300 °C will not lead

Bit-patterned media recording (BPMR) is a candidate technology that extends the density to up to 4 Tb/in 2 to handle large amounts of data. However, in BPMR systems, the major challenge is two-dimensional (2-D) interference, which includes intersymbol interference from the down-track direction and intertrack interference from the across-track direction. To combat 2-D interference, it is natural to

This letter reports the development of low-damping yttrium-iron-garnet (YIG) thin films via sputtering. The films were deposited by sputtering at room temperature first and were then annealed in O 2 at high temperature. It is found that the annealing temperature critically affects the structural properties of the YIG films and thereby dictates the static and dynamic properties of the films. A 75 nm

Integration of yttrium iron garnet (YIG) with Si can bring new avenues for garnet-based complementary metal-oxide semiconductor compatible devices. Herein, investigations on the morphological, electrical, and magnetic properties of postgrowth annealed YIG thin films grown on Si substrate were systematically performed at nanoscale lateral resolution, employing the variants of atomic force microscopy

Spectral, temperature, and magnetic field dependences of the magneto-optical transversal Kerr effect (TKE) as well as optical properties of (In,Mn)As samples prepared by ion implantation followed by pulsed laser melting were studied, and a strong TKE response was detected at low temperatures. The presence of a characteristic structure in the TKE spectra in the transition region around the Λ point of

We present the fabrication process and characterization of a tunnel magnetoresistance sensor-based monolithic device assembled in Wheatstone bridge architecture, capable of measuring magnetic fields in both planar-sensitive directions simultaneously. This process is simplified in comparison with other fabrication strategies, as it does not require annealing or the usage of auxiliary structures to achieve

In this letter, we examine underwater wireless communications using electromagnetic waves in marine shallow waters. Due to the particular environment under study (low frequencies, short distances, and small loop antennas), a magnetoquasi-static approach is used instead of full-wave analysis. The electric field generated by a constant current circular loop placed on the interface between two conductors

We present a spring-shaped tunable inductor, fabricated using a silicon-on-insulator (SOI) multiuser micro-electromechanical system process. The inductor has a simple planar design and is monolithically integrated in the SOI wafer. The inductor is tuned using a thermal actuator on the same silicon structure layer. Thus, the complexity and cost of fabrication are greatly minimized. The device is compact

Magnetic insulators, in particular, rare-earth iron garnets, have low damping compared to metallic ferromagnetic materials due to lack of conduction electrons. In analogy to spin-transfer-torque devices, the low-damping nature is presumed to be an advantage for spintronic applications. We report that perpendicular magnetic anisotropy material with low damping actually does not favor reliable spin–orbit

Undoped ZnO nanostructures were deposited on Si (100) substrate using direct-current-unbalanced magnetron sputtering. The nanostructure modification of conelike into rod-shaped nanocolumnars is found after thermal annealing with O 2 . This modification transforms paramagnetism into room-temperature ferromagnetism, induced by Zn vacancy enhancement at the cost of O vacancies. First principles confirm

Recently, nonmetallic ferromagnetic nanowires (NWs) have been implemented in porous templates. Such composite substrates are used to design various microwave, magnetic, and electronic devices. To synthesize ferrite NWs, the precursor solution consists of either magnetic nanoparticles (NPs) dispersed in a polymer as a surfactant or metal nitrates, which are used in a sol–gel method. The magnetic properties

The use of amorphous ferromagnetic microwires has potential for applications in biomedicine and biophysics. Microwire arrays create magnetic fields that are characterized by strong spatial gradients. A system of ferromagnetic microwires with magnetizations across the diameter may efficiently accumulate paramagnetic particles along the wire due to forced diffusion. For typical system parameters, the

Micromagnets in the form of microwires have become a subject of interest in various applications including magnetic field bias elements in miniature actuators, sensors, and manipulators. While the preparation of hard magnetic microwires with sufficiently high magnetization is a difficult task, it can be achieved by using specific crystallization techniques. We present a technique for the fabrication

A miniature magnetic gradient tensor system may be used in small spacecraft for mineral prospecting and detection of unexploded explosive ordnance. The system consists of a magneto-inductive (MI) sensors array, a signal extraction circuit, and a microcontroller. A magnetic gradient full-tensor configuration utilizes four MI sensors arranged in a planar cross structure and is employed to minimize orientation

Flake-shaped FeSi-based metallic amorphous alloy particles, having an aspect ratio as high as 175:1, were prepared by ball-milling gas-atomized amorphous powders of an effective diameter of 20 µm. The starting powder has a saturation magnetic flux density Bs of 1.5 T and a coercivity Hc of 94 A/m. The aspect ratio of the flakes, as well as their magnetic properties, were controlled by milling process

We report the results of scanning tunneling microscopy experiments using iron-coated tungsten tips and current-carrying bismuth selenide (Bi $_2$ Se $_3$ ) samples. Asymmetry in tunneling currents with respect to the change in the direction of bias currents through Bi $_2$ Se $_3$ samples has been measured. It is argued that this asymmetry is the manifestation of surface spin-polarized electron accumulation

The magnetic domain structure of Y 2 (Fe $_{x}$ Co 1– $_{x}$ ) 17 (0.03 < $ x $ < 0.88) intermetallic compounds was investigated via magnetic force microscopy. It is experimentally shown that in the range of $x$ = 0.07 − 0.5, the surface magnetic domain structure of the single crystals reveals domains with typical uniaxial magnetocrystalline anisotropy configuration. The values of the surface energy

Magnetic particle imaging (MPI) is a fast and sensitive technique for imaging of magnetic nanoparticle (MNP) concentrations. MPI directly measures and maps the particle concentration over a measured spatial position. Functional MPI (fMPI) is a specific application of MPI that aims to detect the change of cerebral blood volume (CBV) through imaging. Assuming that the concentration of MNPs in the CBV

We provide a review of the status and challenges for utilizing magnetic tunneling junction (MTJ) based magnetic sensors for power grid applications. We show that, with both modeling and experimental measurement, an optimized MTJ-based magnetic sensor can be utilized to monitor grid current, especially for individual grid lines. From the perspective of the sensor, the sensitivity, signal-to-noise ratio

A set of planar Hall resistance (PHR) sensors was fabricated on rigid and flexible substrates. High signal-to-noise ratio, low offset voltage, nearly zero hysteresis of signal, and excellent linearity were demonstrated for sensors, based on Ta (5 nm)/NiFe (10 nm)/IrMn (10 nm)/Ta (5 nm) thin films, grown on polydimethylsiloxane (PDMS) and parylene C polymeric substrates. The effect of bending on the

Hexagonal platelet barium ferrite was produced through a two-step molten salt synthesis calcined at 850 °C for 5 h with NaCl–KCl as flux, followed by calcination at 400 °C for 5 h with hexamine. Influence of NaCl–KCl and hexamine on the structural, phase composition, surface morphology, and magnetic properties of BaFe 12 O 19 was studied by X-ray diffraction, Fourier transform infrared spectroscopy

The spacecraft-level magnetic budget in the framework of dc magnetic cleanliness programs of space missions is studied and analyzed. This analysis follows the unit-level magnetic characterization test campaigns that are performed in space missions with challenging magnetic cleanliness requirements. Taking into consideration the output of these test results,the total magnetic signature of the spacecraft

In this letter, a novel approach is presented for imaging of metallic objects based on induction sensing. The approach relies on the concept of collection of the point-spread function (PSF) in a linear space-invariant system. For this purpose, the responses of small objects are measured a priori to serve as the PSFs of the imaging system. Then, these PSFs are employed in a test scenario in which the

We present on-chip implementation of an isothermal nucleic acid amplification assay with optomagnetic detection. Isothermal rolling circle amplification (RCA) was designed for the highly specific detection of a single point mutation in the subsequence of the katG catalase peroxidase gene responsible for resistance against the antibiotic isoniazid in Mycobacterium tuberculosis . The assay was integrated

While the effect of bias direct currents on longitudinal giant magnetoimpedance (GMI) has been well studied, there have been very few investigations of their effect on perpendicular GMI. We report an experimental investigation of the influence of bias direct currents on perpendicular GMI in meander-line NiFe/Cu/NiFe/Cu/Cr films. The low-field sensitivity and linearity of perpendicular GMI both increased

We present results of magneto-optical investigations of (CoFeB) x -(Al-O) 100- x film nanocomposites in transverse Kerr effect (TKE) geometry in the spectral range 0.5–4.0 eV and magnetic field up to 3.1 kOe. Nanocomposites were deposited onto a glass-ceramic substrate by ion-beam sputtering. According to the data obtained from resistivity measurements, the percolation threshold is about x per ≈ 57 at

The centimeter-gram-second system of electromagnetic units (EMU) has been used in magnetism since the latter part of the 19th century. The International System of Units (SI), a successor to Giorgi's 1901 rationalized four-dimensional meter-kilogram-second system, was adopted by the General Conference on Weights and Measures in 1960 with the ampere as the fourth base unit. However, EMU remains in common

The International System of Units (SI) is expected to be revised such that all seven base units, including the kilogram, will be defined in terms of fixed numerical values of seven defining constants. The revised SI will include a redefinition of the ampere. One consequence is that the permeability of vacuum will not have a fixed numerical value but will become, in principle, a measurable quantity