Magnetic field sensors are devices that detect and measure magnetic fields around permanent magnets, electrical conductors, and electrical devices. As such, they are particularly relevant for applications in IoT, 5G, smartphones, energy, and biomedical engineering. In this context, dedicated research is being carried out on novel thin film composite magnetoelectric (ME) sensor concepts for the...
The microwires due to their dimensions have a huge potential in wide fields from agricultural, medical, and technological high-end applications such as sensors or actuators. On the one hand, designing different types of materials for each application is possible. On the other hand, there is the scalability of dimensions, which brings opportunities to control the physical properties of the...
Biomedical applications typically require very low noise magnetic sensors, since the magnetic field to be measured are usually very small. Traditionally SQUIDs have been the only sensors able to reach noise levels low enough to be employed in this field. However, the necessity of cryogenic temperature limits the applications of these sensors to fields where extremely low noise is required....
Performance of planar Hall magnetoresistive (PHMR) sensors was measured in different specification, such as sensor layer thickness, geometry [1]. We figured out the change in PHMR sensor performance for each factors and applied into magnetic encoder experiments. In this magnetic encoder experiments, PHMR sensor was located near to steel gear and permanent magnet was located behind the PHMR...
Our research explores the potential use of semiconductor thin-film materials and graphene-based structures for magnetic field detection in harsh environments, particularly in thermonuclear reactors. We have conducted preliminary research to investigate the impact of high temperature [1] and neutron irradiation [2,3] on the electrical properties of these sensors. Our studies involved a 2D...
Developing portable sensors is crucial for improving the detection of biological agents. These devices enable rapid, on-site analysis, providing real-time monitoring that is vital for applications such as disease diagnosis and environmental monitoring or the pathogen detection including viruses and bacteria. Portable sensors are compact, lightweight, and easy to use, making them suitable for...
Among other gases, the detection of relative humidity (RH) is crucial in air quality monitoring, food storage or industrial processes control. We present here a wireless humidity sensor based on the magnetoelastic resonance (MER) phenomenon. MER sensors are usually made of magnetostrictive ribbons, which can be driven to mechanical resonance via magnetic field excitation. The basis of their...
Composite magnetic materials have been explored for several applications ranging from biomedical to robotics [1]. The ability to incorporate homogeneous and dense nanoparticles in elastomer matrix creates opportunities for the integration with magnetic sensors in flexible electronics [2], providing viable for large area applications. In addition, biocompatibility between the elastomers and...
When designing a magnetic tunnel junction (MTJ) sensor, Key Performance Indicators (KPIs) such as sensitivity, linear operating field range and electrical resistance are set by the application specifications. One of the critical design parameters to tune is the geometry of the MTJ device, as shape, dimension, and aspect ratio directly impact KPIs [1]. By choosing the geometry of the device, it...
Spin-orbit torque (SOT) provides a fast and efficient way to manipulate the magnetization in magnetic devices such as magnetoresistive random access memory (MRAM) [1]. These devices take advantage of the strong spin-orbit coupling (SOC) in the bulk or at the interfaces of heavy metal (HM) layers to generate spin polarized currents. The spin currents are injected into an adjacent ferromagnet...
Magnetoresistive magnetic sensors play a key role in sensing magnetic fields at room temperature, with applications spanning from information storage to biomagnetism. Extraordinary magnetoresistive (EMR) sensors are a promising class of magnetoresistive sensors, which exhibit a magnetoresistance on the order of $7.5\times 10^5\,\%$ at 4T [1]. The extraordinary magnetoresistance is a...
Physics-Informed Neural Networks (PINNs) are a novel class of neural networks that enable the integration of machine learning and physical laws. This relatively recent algorithmic technology, introduced in 2019, has numerous important scientific applications in engineering sciences, such as real-time simulation, digital twins, inverse computation, and finite element methods.
In this work,...
For several years, considerable attention has been devoted to advancing high-sensitivity magnetic sensors to enhance measurement capabilities. A recent trend in this pursuit involves leveraging magnonic devices for sensor construction. While only a limited number of studies have produced and characterized such devices, initial performance outcomes appear promising.
These devices harness the...
Servo motors are drivers that accurately control position, speed, acceleration, etc. according to command signals and are mainly used in processes that require precise control, such as semiconductor processes. The precision of servomotors used in precision processes determines the completeness of the final product and accounts for the main power consumption excluding the heating process within...
In the case of the permanent magnet electronic brake that will be discussed in this paper, a permanent magnet is placed at the bottom of the stator and a winding is placed in the middle of the stator. In the case of attractive force, it is generated by magnetic energy generated by permanent magnets, and current must be applied to the winding to cancel out the stopping force. In the case of a...
Rapidly solidified amorphous submicronic glass-coated wires with diameters between 100 and 950 nm, featuring either high or nearly zero magnetostriction, present a bistable magnetic behavior [1], which relies on the propagation of a single magnetic domain wall at velocities that differ considerably in wires with high magnetostriction as compared to those with nearly zero...
In the automotive industry, ensuring the highest quality of welded components is vital for safety and meeting end-user expectations. Current quality control (QC) practices in welding operations primarily rely on mechanical inspection and reactive procedures. To enhance QC efficiency and anticipate quality issues without destructive testing, it is necessary to apply non-destructive testing...
Magnetic nanoparticles have been the subject of much research with their unique properties such as size in the nanoscale and the existence of high magnetic moment which bring a wide range of their applications. It is their ability to respond to an external magnetic field that enables their motion control. Their application in biomedicine is interesting, where they show promise as drug...
Heusler alloys are suitable materials for sensors and actuators [1]. The current challenge in the utilization of shape memory Heusler alloys remains in their downsizing [2]. In this work we present such materials in the form of thin films and nanowires, which were fabricated using electrodeposition. This approach presents a scalable method for fabrication of shape memory materials, which can...
This study investigates the magnetic properties of ZnFe$_2$O$_4$ thin films, emphasizing the impact of growth conditions on their ferromagnetic resonance (FMR) spectra. Utilizing X-ray diffraction (XRD) and Raman spectroscopy, the films were analysed under different substrates, growth temperatures, and gas ambient. Key findings highlight variations in change in FMR line width, saturation...
Magnetic Heusler alloys, which undergo a martensitic-like structural transition, display interesting functional properties. Regarding the synthesis of these alloys, most of the work conducted up to now has focused on bulk and ribbon samples prepared using conventional melting and melt-spinning techniques. This work reports the microstructure, structural, magnetic, and magnetocaloric...
Nowadays, we are immersed in a digital society where information is continually transferred between different devices, forcing us to look for new alternatives that allow the faster transfer of information with the lowest possible energy consumption. Magnetic thin films have been successfully used but their related natural resonance frequency is restricted to the range of a few GHz, and it...
The inductance of an IPM motor is an important factor in determining the performance of the motor.In particular, spoke type motors use salient pole ratios to utilize reluctance torque, so accurate inductance calculation is an important technique. Many papers have previously been published on inductance calculation methods [1-2]. Recently, with the development of computers, the method of...
Heusler alloys are a unique class of materials which enable the option to change their physical properties by simple adjustment of the alloy's chemical composition. It was shown in different studies, that changes in chemical composition can lead to tuning of the observed phenomenon, and its enhancement. Well-known Heusler ferromagnetic superconductor Ni$_2$NbSn has a critical temperature of 3...
ErMnO$_3$ is the improper multiferroic compound with ferroelectric ordering temperature of $T_c$ = 835 K, but with the magnetism presented only below Neel temperature of $T_N$ = 81 K [1]. This temperature is too low for the application purposes. On the other hand, ErFeO$_3$ system does not exhibit the ferroelectric ordering, but it orders magnetically into antiferromagnetic structure below...
This study examined the effect of the ratio and type of insulation used on the magnetic performance of NiFeMo-based SMCs. We prepared five samples: pure NiFeMo “S1”, two composites with BN-based insulation (1.16 vol$\%$ “S2” and 5 vol$\%$ “S3”), and two Al$_2$O$_3$ (1.16 vol$\%$ “S4” and 5 vol$\%$ “S5”). The ferromagnetic part and the insulator were mixed in 30 ml vials and placed in a...
Iron nanoparticles have emerged as a promising frontier in the realm of nanomedicine, offering unprecedented potential for revolutionizing diagnostics, imaging, targeting, drug delivery, and therapy [1]. Their unique physicochemical properties, such as high surface area-to-volume ratio, tunable magnetic properties, and biocompatibility, make them ideal candidates for various biomedical...
In this work, we confirmed that reversible magnetization mechanisms also contribute to the hysteresis of the magnetizing reversal, and are accompanied with an energy loss, which was explained as originating from the frictional effects when local spins rotate. We modelled this hysteresis by calculating the area of the small hysteresis loops obtained by integrating of the reversible relative...
Ni$_2$FeGa shape memory microwire is a potential material for micro-actuators [1]. One of the methods to demonstrate the actuator property of microwire could be provided by the joule heating method [2]. Interestingly, the micro-diameter (r) of shape memory microwire gives high electric resistance (R) wire following the specific electrical resistivity equation.
$R = \rho \frac{L}{\pi...
The jumps detected in the single-peak and the double-peak GMI ratio dependences of glass-covered CoSiB microwires [1] have been identified as the complex shape pulses in a modified experiment of Sixtus and Tonks. The shape of the induced pulses is given by a combination of two processes: the irreversible movement of the single domain wall and the radial displacement of the transition region...
Amorphous glass-coated microwires are composite materials that consist of metallic core covered by a glass coating. It has been shown that the domain wall propagation in microwires is accompanied by induction of electric voltage at the ends of the wire [1] (Fig. 1a). It arises from a small circular component of the magnetization (Fig. 1a) that is introduced to microwires during their...
Utilizing permanent magnets (PM) in technological applications for information storage and green-energy generation is increasingly important. This necessitates the development of new magnetic materials that are more cost-effective and contain fewer critical components, such as rare earth (RE) elements. However, the systematic exploration of novel hard magnetic materials is a complex task due...
Fe-based metallic glasses (MGs) exhibit superior soft magnetic properties such as a very low coercivity and power losses, a low magnetostriction and a high permeability [1]. Their magnetic properties can be further optimized by modification of post-processing conditions, such as temperature and duration of heat treatment. Structural characterization of MGs at the atomic level represents an...
Annealing of amorphous Vitroperm-800 alloy in the form of thin ribbons under tensile stress is very effective way of achieving huge value of magnetic anisotropy, which may well exceed the value of magneto-crystalline constant (8 kJ/m$^3$) of Fe-Si crystalline phase [1]. As a result of such thermo-mechanical treatment ribbons reveal perfectly linear hysteresis loop with constant slope...
Thin magnetic cylindrical wires attract considerable attention due to interesting features of a domain wall motion like absence of the Walker breakdown that prevents fast domain wall dynamics [1]. Amorphous glass-coated microwires are composite material, in which very high domain wall velocities have been observed [2]. Owing to the amorphous state of wires, the magneto crystalline anisotropy...
Magnetization dynamics by pulse excitation in amorphous wire is limited in the surface layer by skin effect due to magnetic rotation. We have constituted highly sensitive linear micro magnetic field sensors utilizing off-diagonal Magneto-Impedance (MI) effect [１]. Recently we have succeeded in producing pico-Tesla ($10^{-8}$ Oe) resolution MI sensors [2] due to ultra-low intrinsic magnetic...
Classically, the ultimate or intrinsic noise of a sensor is studied/given by the help of the Fluctuation Dissipation Theorem (FDT). Here, we have investigated the magnetic noise of the Planar Hall MagnetoResistance (PHMR) sensor [1] based on this phenomenological physical description [2] and experimental measurements. Indeed, the ellipse surface given by the sensor response, lying $B$ (sensed...
Flat 2-D alignment sensors are required by the printing industry for precise mounting of the plate on the drum to avoid position misalignment in the overlapped patterns. Another application is for the coil alignment for contactless charging. High linearity is not required as the sensor serves as a null indicator in the automatic alignment process. The sensor should be very thin and the moving...
This work introduces a miniaturized fluxgate sensor integrated on a chip fabricated using CMOS technology. The sensor uses a "acetrack" shape of the core, laser-cut out of a 25 $\mu$m thick sheet of VITROVAC 6025F amorphous metal. The structure is Vacquier type, with solenoid excitation and sensing coils. The coils are fabricated using chip’s metal layer and bonding wires. The sensing coil...
3D Packing emerges as a novel method to push the detectivity of TMR sensors to state-of-the-art pT detectivities by vertically connecting TMR sensors in parallel. Diverging from conventional sensor design strategies that rely on creating 2D arrays, this innovative approach preserves a compact footprint crucial for high spatial resolution where xMR technologies excel [1].
In this work, we...
Continuous non-invasive monitoring of vital signs, such as heart rate and blood pressure, is essential for preventive care and managing chronic conditions. Techniques like photoplethysmography (PPG) and electrocardiogram are widely used to extract these signals, but they have limitations in terms of working conditions due to the requirement of good skin contact.To address the limitations of...
Magnetic microsensors have been proposed for the monitoring of various processes and functionalities for diverse industries and soft magnetic materials can be used for a large variety of sensors [1]. Amorphous ferromagnetic and nanocrystalline wires show interesting properties for giant magnetoimpedance (GMI) or domain wall propagation. The effectiveness of the GMI is connected to the applied...
Magnetotactic bacteria are aquatic microorganisms able to swim along the Earth’s magnetic field lines thanks to an internal chain of magnetic nanoparticles that acts as a compass needle. These nanoparticles, called magnetosomes, are composed of a high purity crystalline magnetic core surrounded by a lipid bilayer membrane. For example, as a typical magnetotactic bacteria, the *Magnetospirillum...
Magnetoresistive sensors can deliver high sensitivity and spatial resolution in magnetic field detection, ideal to leverage applications in navigation, robotics or biomedicine. Being able to manipulate the device’s properties, as needed and during operation, has the potential to push further the limits of performance, and broaden applications of spintronic sensors. In this talk, recent results...
Anisotropic Magnetoresistive (AMR) sensors provide a straightforward, low cost and low power consumption solution for magnetic field sensing applications [1]. Despite being a mature technology, a vertical sensor packing strategy in parallel electrical connection can be beneficial for AMR devices, by reducing their electrical noise without increasing the device footprint. These advantages were...
Magnetic field detection devices are highly valuable in many industries, thanks to the fact that they can measure various quantities such as position, movement, direction, and rotational speed. Nowadays, there is a high demand for electronics that can function reliably in harsh environments, including those that can withstand extreme temperatures. Traditional electronics design often requires...
Many technological applications require low permeability of a few hundreds being constant over a wide magnetic field range. For example, this is a case of magnetic energy storage cores [1]. It is well known that magnetic anisotropy induced by stress applied during annealing can reach magnitudes up to several thousands of J/m$^{3}$ which is about two orders of magnitude larger than the magnetic...
Presented article briefly explain the history and the success of applied magnetism, that has been the main focus of research and development scientist group originally seated at Slovak Air Force Academy of Milan Rastislav Štefánik in Košice. The group was focused on measuring of magnetic field since 1982 when they develop the first digital magnetometer in former Czechoslovakia.
Knowledge...
The magnetoelectric (ME) effect is promising and has been studied for several applications: magnetic sensors [1], current sensors [2], energy harvesting [3] and wireless energy transmission. The extrinsic ME effect is preferred to the intrinsic one for these applications, requiring a magnetostrictive material mechanically coupled to a piezoelectric material. Current sensors based on extrinsic...
Magnetic refrigeration is a non-conventional cooling method providing environmentally friendly and more efficient cooling. One of the main advantages of magnetocaloric cooling is the scalability of the used material to the required application. On the other hand, decreasing the size will naturally cause a reduction of cooling power which may be solved by using higher magnetic field changes....
Many materials and machines that may pose a real risk of catastrophe due to fatigue wear, exceeding stress limits or the appearance of plastic deformation are magnetic. In addition, there is a constant trend indicating the need to develop methods towards the technology of detecting early stages of damage, which is possible thanks to the use of magnetic methods [1]. However, due to the variety...
A new experiment (Fig. 1) is presented for studying the dynamics of a single domain wall (DW) driven by an alternating magnetic field. The bistable cylindrical glass-coated microwire is placed in a system of four coaxial coils. One pair of coils in Helmholtz geometry (HC) in parallel combination allows the whole wire to be axially magnetized. This pair of coils in antiparallel combination...
The shear force sensor developed in this study has pressure insensitivity, high sensitivity, and bi-directional measurements, and it was fabricated on a flexible substrate. This sensor was fabricated by applying a polymer based pillar structure to the Planar Hall Magnetoresistance (PHMR) sensing element. The column structure was placed on the PHMR sensing element to minimize the effect of...
With the rapid development of automated driving, real-time vehicle speed estimation can assist in monitoring road traffic condition and predicting change in traffic volume. Direct transmission of detected traffic information to vehicles in real-time is referred to as Vehicle-to-Infrastructure (V2I) communication, which is essential in automated driving. Magnetic sensor technology, due to its...
Our group has experimented in the past with development of contactless position sensors suitable for retrofitting to pneumatic actuators - i.e. piston position sensing [1,2]. The proposed advantage was AC-operation enabling use of synchronous detection and suppression of noise (including DC). Excitation at low frequency (<100 Hz) made possible measurement through aluminum sheath (piston...
The position sensors are widely used in various industrial applications. The sensors with linear variable differential transformer (LVDT) configuration are the most common position transducers because of their cost-effective and simple structure and straightforward operation. LVDT position sensors are used in robotics, automation, manufacturing and machining processes, automatic valves, and...
With the increasing communication needs in harsh environment such as underground, submarine or biological tissues where communications methods with radiofrequency (RF) waves are very difficult, the magnetic communication methods, in which the message is transmitted via the magnetic field, are drawing more and more attention. The advantage is the ability of magnetic field to penetrate all...
The development of steel stress coupons, including an amount of residual stresses up to the yield point has been proven useful for the development of the Magnetic Stress Calibration (MASC) Curves [1]. These coupons were developed by autogenous welding in different types of steels in order to compare surface and bulk residual stresses determined by X-ray diffraction in the Bragg – Brentano...
Fluxgate sensors exhibit the highest sensitivity among the magnetic sensors for detecting d.c. or low frequency a.c. magnetic fields in the $\mu$T range and below. Typically, in a basic fluxgate sensor, the information about the magnetic field is extracted from either the amplitude of the induced signal or the higher-order harmonics of the excitation signal. Another alternative is to extract...
AMR magnetometers are used in many applications where low power consumption is desired, particularly in space applications [1] where it is one of crucial parameters. Although fluxgate/optically pumped magnetometers dominate space industry due to their ultralow-noise, AMRs are increasingly used if the roughly 100-fold increase of noise is not an issue, as they are miniature, lightweight, solid...
Today adhesive technology is of particular importance in different industrial sectors, for example in automotive industry or in aerospace technology [1]. In building industry adhesive technology is often used to avoid punctual transmissions of power. Glued glass elements in constructional engineering are only one example of application. However, the adhesive joint is subject of an ageing...
In this contribution we present development of a device and means of establishing low magnetic fields (<1nT), such as a remanence in a magnetic shield. In a previous development [1], we used a rotating AMR magnetometer for establishing and maintaining near-zero field in a coil system, where rotation enables suppression of the inherent sensor offset and its drift without frequent...
Construction of a digital lock-in amplifier [1] specifically designed for fluxgate sensor testing is presented together with first results. The instrument is based on a low-noise, multi-stage, fully-differential, analog front-end (G = 0.1 - 100$\times$), followed by 1 MSa/s, 20-bit, SAR-ADC (LTC2378) for high dynamic range. All necessary digital signal processing is done within a Cyclone V...
Co-rich amorphous ribbons with nearly zero magnetostriction are well known for their outstanding giant magnetoimpedance (GMI) sensor characteristics [1,2]. However, their relatively low Currie temperature can be a disadvantage for their application at elevated temperatures. In this work, the effects of temperature on magnetoimpedance response were investigated in stress annealed commercial...
One of the practical applications of pulsed magnetic fields (PMF) is in magnetotherapy systems. These systems often generate low-frequency PMF for non-invasive therapy of muscles or bones. Some PMF system manufacturers use commercial teslameters with a Hall probe to measure the generated amplitude of the magnetic flux density $B_m$. However, the traceability and accuracy measurements of $B_m$...
Measuring changes in physical quantities without direct contact is still challenging in sensor applications. Especially in the case of structural member monitoring, it is quite difficult to substitute conventional electrical strain gauges with contactless technology.
A promising solution can be found in magnetically bistable glass-coated microwires. The small dimensions of microwires make...
Existing societal challenges require advancing innovative, eco-friendly technologies and the capacity to manufacture 3D structures sustainably and profitably. Progress in caloric materials, such as magneto- or elasto-caloric compounds, as integral components of the forthcoming generation of energy-efficient devices, offer new opportunities for exploring potential breakthroughs in additive...
The study of the propagation of a single domain wall (DW) is quite important for technological applications in order to understand and improve the operating features of devices based on DW logic. For that purpose, Fe-rich amorphous glass-coated microwires are excellent candidates as their magnetization process consists in the depinning of a single DW that propagates through the microwire at...
Harnessing extra degrees of freedom in magnetic oxides is of vital importance to bring new functionalities to cooling technology. The present study reports on the magnetocaloric effect (MCE) and magnetic exchange bias effect in the SrRuO$_{3}$ single layer and BiFeO$_{3}$/SrRuO$_{3}$ bilayers. MCE and exchange bias behaviors are found to be governed by Ru vacancies, structural distortions, and...
Technological demand for soft magnetic materials capable of operation at high temperatures has led to an increased interest in FeCo-based nanocrystalline alloys. Magnetic components in various energy conversion devices and sensors are during their operation often exposed to high temperature environments, which could have a marked impact on their performance. Therefore, a better knowledge about...
Studies of temperature dependence of the Giant magnetoimpedance, GMI, effect become essentially relevant from the viewpoint of applications of magnetic wire inclusions embedded in multifunctional composite materials for non-destructive and non-contact stress and temperature monitoring [1]. Most of the few studies on temperature dependence of GMI were performed in thick amorphous wires without...
The experimental evidence of large magnetoresistance in magnetite pellets is provided in this paper. Applying magnetic field along the length of the four-point probe resistivity monitoring, on the surface of a bulk magnetite pellet, results in elevated magnetoresistance change in the order of 100$\%$. Measurements were realized in $10^{-3}$ mbar vacuum with excitation currents from 0.1 A up to...
The Giant Magneto-Impedance effect, which changes impedance of amorphous wire in response to the magnetic fields, is used in highly sensitive magnetometers for measuring biomagnetic fields, electronic compasses, and other applications. GMI sensor face a trade-off between sensitivity and wide dynamic range. GMI sensors with sensitivity on the order of pico-tesla, suitable for biomagnetic...
The traditional wireless communication based on electromagnetic waves face difficulties when functioning in the harsh environments like underground, submarine or biological tissues. These difficulties are due to the rapid attenuation of the radio wave in these media. The communication method based on the magnetic field is the alternative solution for such scenarios because the magnetic field...
The aim of the ongoing research at our department in the field of magnetometers is the development of a compact modular magnetometric system operating with amorphous strips and microwires, used as a core. The motivation is in long-term research, development and testing of magnetometers with different types of control and processing electronics. The use of FPGA or CPLD devices for control and...
Magnetic field sensors are essential in our modern-day society, utilized in various applications including automobiles, mobile phones, and robotics. In this talk, I will discuss our work on magnetic field sensors that exploit spin orbit torque (SOT) to detect all three components of an external field with a single device. Initially, the focus will be on sensors where the signal is derived from...
The magnetoimpedance effect (MI) is an attractive phenomenon for several applications, such as magnetic field, stress, and temperature measurement, health monitoring and biological detection. To fully exploit the potential of these applications, it would be useful to develop numerical models able to predict the MI response under different conditions, accounting for materials with diverse...
Analytical expressions are favored for magnetic field calculations due to their speed compared to finite element simulations [1]. They excel in optimizing high-dimensional systems, allowing efficient exploration of parameter spaces, beneficial for designing cost-effective, robust, and accurate magnetic sensor systems [2]. Despite their usefulness, analytical expressions suffer from the...
An energy harvester is a device that converts ambient energy from various sources such as light, vibration, or heat into electrical energy for powering electronic devices in situations where it is not practical to rely on conventional power sources, such as batteries or connections to the electrical grid. There are different types of energy harvesters, each designed to take advantage of...
Extraordinary magnetoresistance (EMR) sensors are geometry-dependent 4-terminal devices based on high-conductivity semiconductors and metal inclusions, that can achieve over $10^6\,\%$ magnetoresistance ratios [1,2]. The origin of such effect can be explained by Lorentz force, rewriting the conductivity tensor of the semiconductor with a magnetic field dependence. Deviations of the current...
