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9 pages, 1953 KiB

Open AccessArticle

Planar Hall Effect and Magnetoresistance Effect in Pt/Tm₃Fe₅O₁₂ Bilayers at Low Temperature

by Yukuai Liu, Jingming Liang, Zhiyong Xu, Jiahui Li, Junhao Ruan, Sheung Mei Ng, Chuanwei Huang and Chi Wah Leung

Electronics 2025, 14(15), 3060; https://doi.org/10.3390/electronics14153060 - 31 Jul 2025

Viewed by 221

Abstract

Spin transport behaviors in heavy metal/ferromagnetic insulator (HM/FI) bilayers have attracted considerable attention due to various novel phenomena and applications in spintronic devices. Herein, we investigate the planar Hall effect (PHE) in Pt/Tm₃Fe₅O₁₂ (Pt/TmIG) heterostructures at low temperatures; moment switching in the ferrimagnetic insulator TmIG is detected by using electrical measurements. Double switching hysteresis PHE curves are found in Pt/TmIG bilayers, closely related to the magnetic moment of Tm³⁺ ions, which makes a key contribution to the total magnetic moment of TmIG film at low temperature. More importantly, a magnetoresistance (MR) curve with double switching is found, which has not been reported in this simple HM/FI bilayer, and the sign of this MR effect is sensitive to the angle between the magnetic field and current directions. Our findings of these effects in this HM/rare earth iron garnet (HM/REIG) bilayer provide insights into tuning the spin transport properties of HM/REIG by changing the rare earth. Full article

(This article belongs to the Section Electronic Materials, Devices and Applications)

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13 pages, 2620 KiB

Open AccessArticle

Systematic Analysis of Driving Modes and NiFe Layer Thickness in Planar Hall Magnetoresistance Sensors

by Changyeop Jeon, Mijin Kim, Jinwoo Kim, Sunghee Yang, Eunseo Choi and Byeonghwa Lim

Sensors 2025, 25(4), 1235; https://doi.org/10.3390/s25041235 - 18 Feb 2025

Cited by 1 | Viewed by 664

Abstract

Planar Hall magnetoresistance (PHMR) sensors are widely utilized due to their high sensitivity, simple structure, and cost-effectiveness. However, their performance is influenced by both the driving mode and the thickness of the ferromagnetic layer, yet the combined effects of these factors remain insufficiently explored. This study systematically investigates the impact of Ni₈₀Fe₂₀ thickness (5–35 nm) on PHMR sensor performance under constant current (CC) and constant voltage (CV) modes, with a focus on optimizing the peak-to-peak voltage (V_p-p). In CC mode, electron surface scattering at 5–10 nm increases resistance, leading to a sharp rise in V_p-p, followed by a decline as the thickness increases. In contrast, CV mode minimizes resistance-related effects, with sensor signals predominantly governed by magnetization-dependent resistivity. Experimentally, the optimal V_p-p was observed at 25 nm in CV mode. However, for thicknesses beyond this point, the reduction in sensor resistance suggests that voltage distribution across both the sensor and external load resistance significantly influences performance. These findings provide practical insights into optimizing PHMR sensors by elucidating the interplay between driving modes and material properties. The results contribute to the advancement of high-performance PHMR sensors with enhanced signal stability and sensitivity for industrial and scientific applications. Full article

(This article belongs to the Special Issue Smart Magnetic Sensors and Application)

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25 pages, 7639 KiB

Open AccessArticle

Designing a Spintronic Based Magnetoresistive Bridge Sensor for Current Measurement and Low Field Sensing

by Cristian Mușuroi, Marius Volmer, Mihai Oproiu, Jenica Neamtu and Elena Helerea

Electronics 2022, 11(23), 3888; https://doi.org/10.3390/electronics11233888 - 24 Nov 2022

Cited by 5 | Viewed by 2391

Abstract

An exchanged-biased anisotropic magnetoresistance bridge sensor for low currents measurement is designed and implemented. The sensor has a simple construction (single mask) and is based on results from micromagnetic simulations. For increasing the sensitivity of the sensor, the magnetic field generated by the measurement current passing through the printed circuit board trace is determined through an analytical method and, for comparative analysis, finite elements method simulations are used. The sensor performance is experimentally tested with a demonstrator chip. Four case studies are considered in the analytical method: neglecting the thickness of the trace, dividing the thickness of the trace in several layers, and assuming a finite or very long conductive trace. Additionally, the influence of several adjacent traces in the sensor area is evaluated. The study shows that the analytical design method can be used for optimizing the geometric selectivity of a non-contacting magnetoresistive bridge sensor setup in single trace, differential, and multi-trace (planar coil) configurations. Further, the results can be applied for developing highly performant magnetoresistance sensors and optimizations for low field detection, small dimensions, and low costs. Full article

(This article belongs to the Special Issue Advanced Magnetic and Electrical Characterization Techniques)

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21 pages, 5779 KiB

Open AccessArticle

Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

by Taehyeong Jeon, Proloy Taran Das, Mijin Kim, Changyeop Jeon, Byeonghwa Lim, Ivan Soldatov and CheolGi Kim

Sensors 2021, 21(20), 6891; https://doi.org/10.3390/s21206891 - 18 Oct 2021

Cited by 7 | Viewed by 3988

Abstract

The resolution of planar-Hall magnetoresistive (PHMR) sensors was investigated in the frequency range from 0.5 Hz to 200 Hz in terms of its sensitivity, average noise level, and detectivity. Analysis of the sensor sensitivity and voltage noise response was performed by varying operational parameters such as sensor geometrical architectures, sensor configurations, sensing currents, and temperature. All the measurements of PHMR sensors were carried out under both constant current (CC) and constant voltage (CV) modes. In the present study, Barkhausen noise was revealed in 1/f noise component and found less significant in the PHMR sensor configuration. Under measured noise spectral density at optimized conditions, the best magnetic field detectivity was achieved better than 550 pT/√Hz at 100 Hz and close to 1.1 nT/√Hz at 10 Hz for a tri-layer multi-ring PHMR sensor in an unshielded environment. Furthermore, the promising feasibility and possible routes for further improvement of the sensor resolution are discussed. Full article

(This article belongs to the Special Issue Design and Applications of Magnetic Sensors)

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13 pages, 4348 KiB

Open AccessCommunication

Bridge Resistance Compensation for Noise Reduction in a Self-Balanced PHMR Sensor

by Jaehoon Lee, Changyeop Jeon, Taehyeong Jeon, Proloy Taran Das, Yongho Lee, Byeonghwa Lim and CheolGi Kim

Sensors 2021, 21(11), 3585; https://doi.org/10.3390/s21113585 - 21 May 2021

Cited by 12 | Viewed by 4309

Abstract

Advanced microelectromechanical system (MEMS) magnetic field sensor applications demand ultra-high detectivity down to the low magnetic fields. To enhance the detection limit of the magnetic sensor, a resistance compensator integrated self-balanced bridge type sensor was devised for low-frequency noise reduction in the frequency range of 0.5 Hz to 200 Hz. The self-balanced bridge sensor was a NiFe (10 nm)/IrMn (10 nm) bilayer structure in the framework of planar Hall magnetoresistance (PHMR) technology. The proposed resistance compensator integrated with a self-bridge sensor architecture presented a compact and cheaper alternative to marketable MEMS MR sensors, adjusting the offset voltage compensation at the wafer level, and led to substantial improvement in the sensor noise level. Moreover, the sensor noise components of electronic and magnetic origin were identified by measuring the sensor noise spectral density as a function of temperature and operating power. The lowest achievable noise in this device architecture was estimated at ~3.34

nV / \sqrt{Hz}

at 100 Hz. Full article

(This article belongs to the Special Issue Design and Applications of Magnetic Sensors)

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