Tatiana Eggers - Academia.edu (original) (raw)

Papers by Tatiana Eggers

Research paper thumbnail of Magneto-optical Kerr Effect Analysis of Magnetic Anisotropy in Soft Ferromagnets

Part of the Physics Commons This Thesis is brought to you for free and open access by the Graduat... more Part of the Physics Commons This Thesis is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact scholarcommons@usf.edu.

Research paper thumbnail of Optimization of high frequency magnetoimpedance effect of Fe-rich microwires by stress-annealing

Research paper thumbnail of Exchange bias and interface-related effects in two-dimensional van der Waals magnetic heterostructures: Open questions and perspectives

Journal of Alloys and Compounds

The exchange bias (EB) effect is known as a fundamentally and technologically important magnetic ... more The exchange bias (EB) effect is known as a fundamentally and technologically important magnetic property of a magnetic bilayer film. It is manifested as a horizontal shift in a magnetic hysteresis loop of a film subject to cooling in the presence of a magnetic field. The EB effect in van der Waals (vdW) heterostructures offers a novel approach for tuning the magnetic properties of the newly discovered single-layer magnets, as well as adds a new impetus to magnetic vdW heterostructures. Indeed, intriguing EB effects have recently been reported in a variety of low-dimensional vdW magnetic systems ranging from a weakly interlayer-coupled vdW magnet (e.g., Fe3GeTe2) to a bilayer composed of two different magnetic vdW materials (e.g., Fe3GeTe2/CrCl3, Fe3GeTe2/FePS3, Fe3GeTe2/MnPS3), to bilayers of two different vdW defective magnets (e.g., VSe2/MoS2), or to metallic ferromagnet/vdW defective magnet interfaces (e.g., Fe/MoS2). Despite their huge potential in spintronic device applications, the physical origins of the observed EB effects have remained elusive to researchers. We present here a critical review of the EB effect and associated phenomena such as magnetic proximity (MP) in various vdW heterostructure systems and propose approaches to addressing some of the emerging fundamental questions.

Research paper thumbnail of Magnetoimpedance Biosensors and Real-Time Healthcare Monitors: Progress, Opportunities, and Challenges

Biosensors

A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic con... more A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic conductor in various forms of wire, ribbon, and thin film. Also known as the giant magnetoimpedance (GMI) effect, this phenomenon forms the basis for the development of high-performance magnetic biosensors with magnetic field sensitivity down to the picoTesla regime at room temperature. Over the past decade, some state-of-the-art prototypes have become available for trial tests due to continuous efforts to improve the sensitivity of GMI biosensors for the ultrasensitive detection of biological entities and biomagnetic field detection of human activities through the use of magnetic nanoparticles as biomarkers. In this review, we highlight recent advances in the development of GMI biosensors and review medical devices for applications in biomedical diagnostics and healthcare monitoring, including real-time monitoring of respiratory motion in COVID-19 patients at various stages. We also discus...

Research paper thumbnail of A Novel Magnetic Respiratory Sensor for Human Healthcare

Applied Sciences

Breathing is vital to life. Therefore, the real-time monitoring of a patient′s breathing pattern ... more Breathing is vital to life. Therefore, the real-time monitoring of a patient′s breathing pattern is crucial to respiratory rehabilitation therapies, such as magnetic resonance exams for respiratory-triggered imaging, chronic pulmonary disease treatment, and synchronized functional electrical stimulation. While numerous respiratory devices have been developed, they are often in direct contact with a patient, which can yield limited data. In this study, we developed a novel, non-invasive, and contactless magnetic sensing platform that can precisely monitor a patient′s breathing, movement, or sleep patterns, thus providing efficient monitoring at a clinic or home. A magneto-LC resonance (MLCR) sensor converts the magnetic oscillations generated by a patient′s breathing into an impedance spectrum, which allows for a deep analysis of one′s breath variation to identify respiratory-related diseases like COVID-19. Owing to its ultrahigh sensitivity, the MLCR sensor yields a distinct breathi...

Research paper thumbnail of A perspective on two-dimensional van der Waals opto-spin-caloritronics

Applied Physics Letters

Two-dimensional (2D) van der Waals magnetic semiconductors displaying controllable ferromagnetism... more Two-dimensional (2D) van der Waals magnetic semiconductors displaying controllable ferromagnetism at room temperature form atomically sharp interfaces with various substrates. Such heterostructures create platforms for understanding spin-dependent phenomena across interfaces and surfaces for high-performance technological applications. Combining these 2D magnets with light and the spin Seebeck effect (SSE) in state-of-the-art thermo-opto-spin studies forms a new paradigm in the field of spin-caloritronics that harnesses light as the new heat. In this Perspective, we detail how to exploit recent advances in 2D van der Waals materials to boost the SSE and propose a strategy for optically-controlled SSE in 2D magnetic semiconductor-based heterostructures with the intent to establish the research thrust of "opto-spin-caloritronics". Atomically thin van der Waals magnets and heterostructures are being tapped as the primary components of a next generation of computing devices based on spintronics or optospintronics. 1-3 In addition to their miniaturization, these two-dimensional (2D) magnets are expected to enable faster processing speeds, lower energy consumption, and even increased

Research paper thumbnail of Exploring Resonance Effects on Ferromagnetic Microwire Solenoid Sensitivity for Motion Tracking Applications

Research paper thumbnail of Surface and Interface Effects of Magnetoimpedance Materials at High Frequency

Research paper thumbnail of Surface magnetic properties and magnetoimpedance of Co-rich amorphous and nanocrystalline (Co$_{1-x}$Fe$_{x})_{89}$Zr$_{7}$B$_{4}$ ribbons with oxide layer formed by long-term exposure to air

Bulletin of the American Physical Society, 2016

Research paper thumbnail of Emergent Transition Metal Dichalcogenide Monolayer Ferromagnetism at Terminated Edges

Bulletin of the American Physical Society, 2019

Research paper thumbnail of Detection of Pinned Uncompensated Magnetization in Antiferromagnet Using Magnetotransport and Polarized Neutron Reflectometry

Bulletin of the American Physical Society, 2017

Research paper thumbnail of Impact of DC Joule anneal treatment on the high-frequency magnetoimpedance response of Fe-rich FeCo ribbons with varying glass former content

Bulletin of the American Physical Society, 2016

Research paper thumbnail of Detection of magnetic biomarkers using a single giant magneto-impedance microwire

Bulletin of the American Physical Society, 2018

Research paper thumbnail of Magneto-optical Kerr Eect Study of Magnetic Anisotropy in Soft Ferromagnets

The continued progress of modern information technology relies on understanding the influence of ... more The continued progress of modern information technology relies on understanding the influence of magnetic anisotropy on magnetic thin films. In this work, two sources of magnetic anisotropy are examined in two different soft ferromagnets: a uniaxial anisotropy induced during the fabrication of Ni80Fe20 and exchange anisotropy, or exchange bias, which occurs at the interface of Ni77Fe14Cu5Mo4/Fe50Mn50 bilayer. A home-built Magneto-optical Kerr effect magnetometer is used to measure the magnetic response of the soft ferromagnetic films and details of its construction are also discussed. A simple model of uniaxial anisotropy is described, then applied, to the uniaxial NiFe film and deviations from the model are critically analyzed. The exchange bias and coercive fields of NiFeCuMo/FeMn are reported for the first time and studied as a function of buffer layer material. The influence of the different buffer layer materials on the magnetization response of the bilayer is explained from a ...

Research paper thumbnail of Light‐Controlled Room Temperature Ferromagnetism in Vanadium‐Doped Tungsten Disulfide Semiconducting Monolayers

Advanced Electronic Materials, 2021

Atomically thin transition metal dichalcogenide (TMD) semiconductors hold enormous potential for ... more Atomically thin transition metal dichalcogenide (TMD) semiconductors hold enormous potential for modern optoelectronic devices and quantum computing applications. By inducing long-range ferromagnetism (FM) in these semiconductors through the introduction of small amounts of a magnetic dopant, it is possible to extend their potential in emerging spintronic applications. Here, we demonstrate light-mediated, room temperature (RT) FM, in V-doped WS 2 (V-WS 2) monolayers. We probe this effect using the principle of magnetic LC resonance, which employs a soft ferromagnetic Co-based microwire coil driven near its resonance in the radio frequency (RF) regime. The combination of LC resonance with an extraordinary giant magneto-impedance effect, renders the coil highly sensitive to changes in the magnetic flux through its core. We then place the V-WS 2 monolayer at the core of the coil where it is excited with a laser while its change in magnetic permeability is measured. Notably, the magnetic permeability of the monolayer is found to depend on the laser intensity, thus confirming light control of RT magnetism in this two-dimensional (2D) material. Guided by density functional calculations, we attribute this phenomenon to the presence of excess holes in the conduction and valence bands, as well as carriers trapped in the magnetic doping states, which in turn mediates the magnetization of the V-WS 2 monolayer. These findings provide a unique route to exploit light-controlled ferromagnetism in low powered 2D spintronic devices capable of operating at RT.

Research paper thumbnail of Real-time monitoring of position and motion of a non-stationary object with a highly sensitive magnetic impedance sensor

Journal of Science: Advanced Materials and Devices, 2018

The real-time monitoring of the position and speed of a moving object is crucial for safety compl... more The real-time monitoring of the position and speed of a moving object is crucial for safety compliance in industrial applications. The effectiveness of current sensing technology is limited by sensing distance and messy environments. In this work, a position and speed sensor based on the giant magneto-impedance effect was fabricated using a Joule annealed Co-rich magnetic microwire. The fabricated GMI sensor response was explored over a frequency range of 1 MHze1 GHz. The impedance spectrum showed a high GMI ratio and high field sensitivity response at low magnetic fields. The GMI sensor based longitudinal effect was found to be more sensitive than a commercial Gaussmeter. The practical utility of the high sensitivity of the sensor at weak magnetic fields for far-off distance monitoring of position and speed was demonstrated. This GMI-based sensor is highly promising for real-time position detection and oscillatory motion monitoring.

Research paper thumbnail of Condition Monitoring and Failure Prediction of Gear Rotation Using a Contactless RF Magnetic Sensor

Journal of Electronic Materials, 2019

Development of sensor devices that can precisely detect small tilt angles of an anomalously rotat... more Development of sensor devices that can precisely detect small tilt angles of an anomalously rotating gear is in great demand for real-time condition monitoring and predictive maintenance of gear-based machines. The utility of a high-frequency giant magnetoimpedance (GMI)-based sensor for real-time monitoring of a rotating gear has been demonstrated. The rotation speed and tilt position of a magnetically labeled rotating gear were measured remotely from a distance of 14 cm. Small changes in magnetic field, down to mOe level, were detected using an optimized Co 69.25 Fe 4.25 Si 13 B 12.5 Nb 1 microwire sensor. The sensing element exhibited remarkable field sensitivity (g) and GMI ratio of 230%/Oe and 300%, respectively. This contactless magnetic sensor is useful for future development of real-time condition monitoring and predicting failure of a rotating object.

Research paper thumbnail of Enhancement of Giant Magneto-Impedance in Series Co-Rich Microwires for Low-Field Sensing Applications

Journal of Electronic Materials, 2018

Two soft ferromagnetic Co 68.25 Fe 4.25 Si 12.25 B 15.25 microwires with the same diameter of 50 ... more Two soft ferromagnetic Co 68.25 Fe 4.25 Si 12.25 B 15.25 microwires with the same diameter of 50 ± 1 lm but different fabrication processes were placed in series and in parallel circuit configurations to investigate their giant magneto-impedance (GMI) responses in a frequency range of 1-100 MHz for low-field sensing applications. We show that, while the low-field GMI response is significantly reduced in the parallel configuration, it is greatly enhanced in the series connection. These results suggest that a highly sensitive GMI sensor can be designed by arranging multi-wires in a saw-shaped fashion to optimize the sensing area, and soldered together in series connection to maintain the excellent magnetic field sensitivity.

Research paper thumbnail of Impact of the transverse magnetocrystalline anisotropy of a Co coating layer on the magnetoimpedance response of FeNi-rich nanocrystalline ribbon

Journal of Alloys and Compounds, 2018

There is a pressing need for improving the high-frequency magneto-impedance (MI) response of cost... more There is a pressing need for improving the high-frequency magneto-impedance (MI) response of cost-effective soft magnetic materials for use in high-performance sensing devices. We report here a comparative study of uncoated (Fe 50 Ni 50) 81 Nb 7 B 12 nanocrystalline ribbons and ribbons coated with 120 nm of Co on both surfaces. The impact of the Co coating on the high frequency impedance of the (Fe 50 Ni 50) 81 Nb 7 B 12 ribbon was studied with techniques sensitive to surface magnetism, namely magneto-optical Kerr effect (MOKE), MOKE microscopy, and high frequency impedance as a function of magnetic field. MOKE microscopy on the coated ribbons showed a superposition of high anisotropy domains from the crystalline Co and wide magnetic domains from (Fe 50 Ni 50) 81 Nb 7 B 12. In full agreement with the MOKE results, MI measurements indicated an increase in anisotropy field in the excitation frequency range 100-1000 MHz in the Co-coated ribbons. Noticeably, the Co-coating improved the MI ratio by 15 % at fields near and below the anisotropy field. The improvement of the low-field MI response by the coating encourages the use

Research paper thumbnail of Tailoring circular magnetic domain structure and high frequency magneto-impedance of melt-extracted Co69.25Fe4.25Si13B13.5 microwires through Nb doping

AIP Advances, 2017

Tailoring circular magnetic domain structure and high frequency magneto-impedance of melt-extract... more Tailoring circular magnetic domain structure and high frequency magneto-impedance of melt-extracted Co 69.25 Fe 4.25 Si 13 B 13.5 microwires through Nb doping

Research paper thumbnail of Magneto-optical Kerr Effect Analysis of Magnetic Anisotropy in Soft Ferromagnets

Part of the Physics Commons This Thesis is brought to you for free and open access by the Graduat... more Part of the Physics Commons This Thesis is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact scholarcommons@usf.edu.

Research paper thumbnail of Optimization of high frequency magnetoimpedance effect of Fe-rich microwires by stress-annealing

Research paper thumbnail of Exchange bias and interface-related effects in two-dimensional van der Waals magnetic heterostructures: Open questions and perspectives

Journal of Alloys and Compounds

The exchange bias (EB) effect is known as a fundamentally and technologically important magnetic ... more The exchange bias (EB) effect is known as a fundamentally and technologically important magnetic property of a magnetic bilayer film. It is manifested as a horizontal shift in a magnetic hysteresis loop of a film subject to cooling in the presence of a magnetic field. The EB effect in van der Waals (vdW) heterostructures offers a novel approach for tuning the magnetic properties of the newly discovered single-layer magnets, as well as adds a new impetus to magnetic vdW heterostructures. Indeed, intriguing EB effects have recently been reported in a variety of low-dimensional vdW magnetic systems ranging from a weakly interlayer-coupled vdW magnet (e.g., Fe3GeTe2) to a bilayer composed of two different magnetic vdW materials (e.g., Fe3GeTe2/CrCl3, Fe3GeTe2/FePS3, Fe3GeTe2/MnPS3), to bilayers of two different vdW defective magnets (e.g., VSe2/MoS2), or to metallic ferromagnet/vdW defective magnet interfaces (e.g., Fe/MoS2). Despite their huge potential in spintronic device applications, the physical origins of the observed EB effects have remained elusive to researchers. We present here a critical review of the EB effect and associated phenomena such as magnetic proximity (MP) in various vdW heterostructure systems and propose approaches to addressing some of the emerging fundamental questions.

Research paper thumbnail of Magnetoimpedance Biosensors and Real-Time Healthcare Monitors: Progress, Opportunities, and Challenges

Biosensors

A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic con... more A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic conductor in various forms of wire, ribbon, and thin film. Also known as the giant magnetoimpedance (GMI) effect, this phenomenon forms the basis for the development of high-performance magnetic biosensors with magnetic field sensitivity down to the picoTesla regime at room temperature. Over the past decade, some state-of-the-art prototypes have become available for trial tests due to continuous efforts to improve the sensitivity of GMI biosensors for the ultrasensitive detection of biological entities and biomagnetic field detection of human activities through the use of magnetic nanoparticles as biomarkers. In this review, we highlight recent advances in the development of GMI biosensors and review medical devices for applications in biomedical diagnostics and healthcare monitoring, including real-time monitoring of respiratory motion in COVID-19 patients at various stages. We also discus...

Research paper thumbnail of A Novel Magnetic Respiratory Sensor for Human Healthcare

Applied Sciences

Breathing is vital to life. Therefore, the real-time monitoring of a patient′s breathing pattern ... more Breathing is vital to life. Therefore, the real-time monitoring of a patient′s breathing pattern is crucial to respiratory rehabilitation therapies, such as magnetic resonance exams for respiratory-triggered imaging, chronic pulmonary disease treatment, and synchronized functional electrical stimulation. While numerous respiratory devices have been developed, they are often in direct contact with a patient, which can yield limited data. In this study, we developed a novel, non-invasive, and contactless magnetic sensing platform that can precisely monitor a patient′s breathing, movement, or sleep patterns, thus providing efficient monitoring at a clinic or home. A magneto-LC resonance (MLCR) sensor converts the magnetic oscillations generated by a patient′s breathing into an impedance spectrum, which allows for a deep analysis of one′s breath variation to identify respiratory-related diseases like COVID-19. Owing to its ultrahigh sensitivity, the MLCR sensor yields a distinct breathi...

Research paper thumbnail of A perspective on two-dimensional van der Waals opto-spin-caloritronics

Applied Physics Letters

Two-dimensional (2D) van der Waals magnetic semiconductors displaying controllable ferromagnetism... more Two-dimensional (2D) van der Waals magnetic semiconductors displaying controllable ferromagnetism at room temperature form atomically sharp interfaces with various substrates. Such heterostructures create platforms for understanding spin-dependent phenomena across interfaces and surfaces for high-performance technological applications. Combining these 2D magnets with light and the spin Seebeck effect (SSE) in state-of-the-art thermo-opto-spin studies forms a new paradigm in the field of spin-caloritronics that harnesses light as the new heat. In this Perspective, we detail how to exploit recent advances in 2D van der Waals materials to boost the SSE and propose a strategy for optically-controlled SSE in 2D magnetic semiconductor-based heterostructures with the intent to establish the research thrust of "opto-spin-caloritronics". Atomically thin van der Waals magnets and heterostructures are being tapped as the primary components of a next generation of computing devices based on spintronics or optospintronics. 1-3 In addition to their miniaturization, these two-dimensional (2D) magnets are expected to enable faster processing speeds, lower energy consumption, and even increased

Research paper thumbnail of Exploring Resonance Effects on Ferromagnetic Microwire Solenoid Sensitivity for Motion Tracking Applications

Research paper thumbnail of Surface and Interface Effects of Magnetoimpedance Materials at High Frequency

Research paper thumbnail of Surface magnetic properties and magnetoimpedance of Co-rich amorphous and nanocrystalline (Co$_{1-x}$Fe$_{x})_{89}$Zr$_{7}$B$_{4}$ ribbons with oxide layer formed by long-term exposure to air

Bulletin of the American Physical Society, 2016

Research paper thumbnail of Emergent Transition Metal Dichalcogenide Monolayer Ferromagnetism at Terminated Edges

Bulletin of the American Physical Society, 2019

Research paper thumbnail of Detection of Pinned Uncompensated Magnetization in Antiferromagnet Using Magnetotransport and Polarized Neutron Reflectometry

Bulletin of the American Physical Society, 2017

Research paper thumbnail of Impact of DC Joule anneal treatment on the high-frequency magnetoimpedance response of Fe-rich FeCo ribbons with varying glass former content

Bulletin of the American Physical Society, 2016

Research paper thumbnail of Detection of magnetic biomarkers using a single giant magneto-impedance microwire

Bulletin of the American Physical Society, 2018

Research paper thumbnail of Magneto-optical Kerr Eect Study of Magnetic Anisotropy in Soft Ferromagnets

The continued progress of modern information technology relies on understanding the influence of ... more The continued progress of modern information technology relies on understanding the influence of magnetic anisotropy on magnetic thin films. In this work, two sources of magnetic anisotropy are examined in two different soft ferromagnets: a uniaxial anisotropy induced during the fabrication of Ni80Fe20 and exchange anisotropy, or exchange bias, which occurs at the interface of Ni77Fe14Cu5Mo4/Fe50Mn50 bilayer. A home-built Magneto-optical Kerr effect magnetometer is used to measure the magnetic response of the soft ferromagnetic films and details of its construction are also discussed. A simple model of uniaxial anisotropy is described, then applied, to the uniaxial NiFe film and deviations from the model are critically analyzed. The exchange bias and coercive fields of NiFeCuMo/FeMn are reported for the first time and studied as a function of buffer layer material. The influence of the different buffer layer materials on the magnetization response of the bilayer is explained from a ...

Research paper thumbnail of Light‐Controlled Room Temperature Ferromagnetism in Vanadium‐Doped Tungsten Disulfide Semiconducting Monolayers

Advanced Electronic Materials, 2021

Atomically thin transition metal dichalcogenide (TMD) semiconductors hold enormous potential for ... more Atomically thin transition metal dichalcogenide (TMD) semiconductors hold enormous potential for modern optoelectronic devices and quantum computing applications. By inducing long-range ferromagnetism (FM) in these semiconductors through the introduction of small amounts of a magnetic dopant, it is possible to extend their potential in emerging spintronic applications. Here, we demonstrate light-mediated, room temperature (RT) FM, in V-doped WS 2 (V-WS 2) monolayers. We probe this effect using the principle of magnetic LC resonance, which employs a soft ferromagnetic Co-based microwire coil driven near its resonance in the radio frequency (RF) regime. The combination of LC resonance with an extraordinary giant magneto-impedance effect, renders the coil highly sensitive to changes in the magnetic flux through its core. We then place the V-WS 2 monolayer at the core of the coil where it is excited with a laser while its change in magnetic permeability is measured. Notably, the magnetic permeability of the monolayer is found to depend on the laser intensity, thus confirming light control of RT magnetism in this two-dimensional (2D) material. Guided by density functional calculations, we attribute this phenomenon to the presence of excess holes in the conduction and valence bands, as well as carriers trapped in the magnetic doping states, which in turn mediates the magnetization of the V-WS 2 monolayer. These findings provide a unique route to exploit light-controlled ferromagnetism in low powered 2D spintronic devices capable of operating at RT.

Research paper thumbnail of Real-time monitoring of position and motion of a non-stationary object with a highly sensitive magnetic impedance sensor

Journal of Science: Advanced Materials and Devices, 2018

The real-time monitoring of the position and speed of a moving object is crucial for safety compl... more The real-time monitoring of the position and speed of a moving object is crucial for safety compliance in industrial applications. The effectiveness of current sensing technology is limited by sensing distance and messy environments. In this work, a position and speed sensor based on the giant magneto-impedance effect was fabricated using a Joule annealed Co-rich magnetic microwire. The fabricated GMI sensor response was explored over a frequency range of 1 MHze1 GHz. The impedance spectrum showed a high GMI ratio and high field sensitivity response at low magnetic fields. The GMI sensor based longitudinal effect was found to be more sensitive than a commercial Gaussmeter. The practical utility of the high sensitivity of the sensor at weak magnetic fields for far-off distance monitoring of position and speed was demonstrated. This GMI-based sensor is highly promising for real-time position detection and oscillatory motion monitoring.

Research paper thumbnail of Condition Monitoring and Failure Prediction of Gear Rotation Using a Contactless RF Magnetic Sensor

Journal of Electronic Materials, 2019

Development of sensor devices that can precisely detect small tilt angles of an anomalously rotat... more Development of sensor devices that can precisely detect small tilt angles of an anomalously rotating gear is in great demand for real-time condition monitoring and predictive maintenance of gear-based machines. The utility of a high-frequency giant magnetoimpedance (GMI)-based sensor for real-time monitoring of a rotating gear has been demonstrated. The rotation speed and tilt position of a magnetically labeled rotating gear were measured remotely from a distance of 14 cm. Small changes in magnetic field, down to mOe level, were detected using an optimized Co 69.25 Fe 4.25 Si 13 B 12.5 Nb 1 microwire sensor. The sensing element exhibited remarkable field sensitivity (g) and GMI ratio of 230%/Oe and 300%, respectively. This contactless magnetic sensor is useful for future development of real-time condition monitoring and predicting failure of a rotating object.

Research paper thumbnail of Enhancement of Giant Magneto-Impedance in Series Co-Rich Microwires for Low-Field Sensing Applications

Journal of Electronic Materials, 2018

Two soft ferromagnetic Co 68.25 Fe 4.25 Si 12.25 B 15.25 microwires with the same diameter of 50 ... more Two soft ferromagnetic Co 68.25 Fe 4.25 Si 12.25 B 15.25 microwires with the same diameter of 50 ± 1 lm but different fabrication processes were placed in series and in parallel circuit configurations to investigate their giant magneto-impedance (GMI) responses in a frequency range of 1-100 MHz for low-field sensing applications. We show that, while the low-field GMI response is significantly reduced in the parallel configuration, it is greatly enhanced in the series connection. These results suggest that a highly sensitive GMI sensor can be designed by arranging multi-wires in a saw-shaped fashion to optimize the sensing area, and soldered together in series connection to maintain the excellent magnetic field sensitivity.

Research paper thumbnail of Impact of the transverse magnetocrystalline anisotropy of a Co coating layer on the magnetoimpedance response of FeNi-rich nanocrystalline ribbon

Journal of Alloys and Compounds, 2018

There is a pressing need for improving the high-frequency magneto-impedance (MI) response of cost... more There is a pressing need for improving the high-frequency magneto-impedance (MI) response of cost-effective soft magnetic materials for use in high-performance sensing devices. We report here a comparative study of uncoated (Fe 50 Ni 50) 81 Nb 7 B 12 nanocrystalline ribbons and ribbons coated with 120 nm of Co on both surfaces. The impact of the Co coating on the high frequency impedance of the (Fe 50 Ni 50) 81 Nb 7 B 12 ribbon was studied with techniques sensitive to surface magnetism, namely magneto-optical Kerr effect (MOKE), MOKE microscopy, and high frequency impedance as a function of magnetic field. MOKE microscopy on the coated ribbons showed a superposition of high anisotropy domains from the crystalline Co and wide magnetic domains from (Fe 50 Ni 50) 81 Nb 7 B 12. In full agreement with the MOKE results, MI measurements indicated an increase in anisotropy field in the excitation frequency range 100-1000 MHz in the Co-coated ribbons. Noticeably, the Co-coating improved the MI ratio by 15 % at fields near and below the anisotropy field. The improvement of the low-field MI response by the coating encourages the use

Research paper thumbnail of Tailoring circular magnetic domain structure and high frequency magneto-impedance of melt-extracted Co69.25Fe4.25Si13B13.5 microwires through Nb doping

AIP Advances, 2017

Tailoring circular magnetic domain structure and high frequency magneto-impedance of melt-extract... more Tailoring circular magnetic domain structure and high frequency magneto-impedance of melt-extracted Co 69.25 Fe 4.25 Si 13 B 13.5 microwires through Nb doping