Noise characterization of ultrasensitive anomalous Hall effect sensors based on Co40Fe40B20 thin films with compensated in-plane and perpendicular magnetic anisotropies

Zhang, Yiou; Wang, Kang; Xiao, Gang

doi:10.1063/5.0008949

Cited by 9 publications

(18 citation statements)

References 41 publications

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“…The competition between the two can, in fact, reduce the field detectability. In our recent studies on Ta/Co 40 Fe 40 B 20 /MgO [ 5 ] and MgO/Co 40 Fe 40 B 20 /Ta/Co 40 Fe 40 B 20 /MgO [ 2 ] systems, we found that anomalous Hall sensors have the best performance when the magnetization is tuned to be near the spin-reorientation transition. In Ta/Co 40 Fe 40 B 20 /MgO [ 5 ], the field detectability reaches 76 nT/√Hz at 1 Hz and 2 nT/√Hz at 10 kHz at a perpendicular bias field of −12 Oe.…”

Section: Introductionmentioning

confidence: 94%

“…Anomalous Hall sensors are magnetic sensors that take advantage of the anomalous Hall effect of ferromagnets [ 1 , 2 , 3 , 4 , 5 , 6 ]. Electrons with different spins, under the spin–orbit interaction, deflect towards opposite transverse directions when a longitudinal electric current

is applied [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

“…This gives rise to an anomalous Hall voltage (

, where

is the Hall resistance), which is proportional to the perpendicular magnetization that can be controlled by the external perpendicular magnetic field. For a given magnetic system, the Hall-resistance response, also known as the sensitivity s (in the unit of Ω/T), depends strongly on the magnetic anisotropy of the ferromagnet [ 1 , 2 , 3 , 4 , 5 , 6 ]. The sensitivity, together with the Hall voltage noise

(in the unit of V 2 /Hz), including both the electronic noise originating from defects and the magnetic noise originating from thermal magnetic fluctuations, determines the magnetic field detectability

[ 2 , 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, anomalous Hall sensors have been studied in multiple magnetic systems with different magnetic anisotropies [ 1 , 2 , 3 , 4 , 5 , 6 ]. In the in-plane magnetized materials, although the sensitivity is low compared to conventional semiconductor Hall sensors, the voltage noise is low as well.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, the field detectability is reasonably good at low frequencies [ 4 ]. On the other hand, the sensitivity increases with the emergence of the perpendicular magnetic anisotropy (PMA), which has the tendency to increase the voltage noise as well [ 2 , 5 ]. The competition between the two can, in fact, reduce the field detectability.…”

Section: Introductionmentioning

confidence: 99%

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Micron-Scale Anomalous Hall Sensors Based on FexPt1−x Thin Films with a Large Hall Angle and near the Spin-Reorientation Transition

et al. 2021

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In this work, we fabricate and characterize an energy-efficient anomalous Hall sensor based on soft-magnetic FexPt1−x thin films with a large anomalous Hall angle. By varying the composition of the FexPt1−x alloy, its layer thickness and interfacial materials, the magnetization is tuned to be near the spin transition between the perpendicular and in-plane reorientations. We performed magneto-transport and noise characterizations on anomalous Hall sensors with a small sensing area of 20 × 20 µm2 in the 180 to 350 K temperature range. We found the best performance in a 1.25-nm-thick Fe0.48Pt0.52 sandwiched by two 1.6-nm-thick MgO layers at room temperature. The sensor has a large anomalous Hall angle of 1.95%. Moreover, it has the best field detectability of 237.5 nT/√Hz at 1 Hz and 15.3 nT/√Hz at 10 kHz, as well as a high dynamic reserve of 112.0 dB. These results suggest that the FexPt1−x alloy system is suitable for energy-efficient anomalous Hall sensors, particularly in micro-sensing applications.

show abstract

Section: Introductionmentioning

confidence: 94%

is applied [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

“…This gives rise to an anomalous Hall voltage (

, where

[ 2 , 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Micron-Scale Anomalous Hall Sensors Based on FexPt1−x Thin Films with a Large Hall Angle and near the Spin-Reorientation Transition

et al. 2021

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A Highly Compressible and Stretchable Carbon Spring for Smart Vibration and Magnetism Sensors

et al. 2021

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Porous carbon materials demonstrate extensive applications for their attractive characteristics. Mechanical flexibility is an essential property guaranteeing their durability. After decades of research efforts, compressive brittleness of porous carbon materials is well resolved. However, reversible stretchability remains challenging to achieve due to the intrinsically weak connections and fragile joints of the porous carbon networks. Herein, it is presented that a porous all‐carbon material achieving both elastic compressibility and stretchability at large strain from −80% to 80% can be obtained when a unique long‐range lamellar multi‐arch microstructure is introduced. Impressively, the porous all‐carbon material can maintain reliable structural robustness and durability under loading condition of cyclic compressing–stretching process, similar to a real metallic spring. The unique performance renders it as a promising platform for making smart vibration and magnetism sensors, even capable of operating at extreme temperatures. Furthermore, this study provides valuable insights for creating highly stretchable and compressible porous materials from other neat inorganic components for diverse applications in future.

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Perspective on nanoscale magnetic sensors using giant anomalous Hall effect in topological magnetic materials for read head application in magnetic recording

Nakatani,

Kulkarni,

Suto

et al. 2024

Applied Physics Letters

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Recent advances in the study of materials with topological electronic band structures have revealed magnetic materials exhibiting giant anomalous Hall effects (AHEs). The giant AHE has not only attracted the research interest in its mechanism but also opened up the possibility of practical application in magnetic sensors. In this article, we describe simulation-based investigations of AHE magnetic sensors for applications to read head sensors (readers) of hard disk drives. With the shrinking of magnetic recording patterns, the reader technology, which currently uses multilayer-based tunnel magnetoresistance (TMR) devices, is associated with fundamental challenges, such as insufficient spatial resolution and signal-to-noise ratio (SNR) in sensors with dimensions below 20 nm. The structure of an AHE-based device composed of a single ferromagnetic material is advantageous for magnetic sensors with nanoscale dimensions. We found that AHE readers using topological ferromagnets with giant AHE, such as Co2MnGa, can achieve a higher SNR than current TMR readers. The higher SNR originates from the large output signal of the giant AHE as well as from the reduced thermal magnetic noise, which is the dominant noise in TMR readers. We highlight a major challenge in the development of AHE readers: the reduction in the output signal due to the shunting of the bias current and the leakage of the Hall voltage through the soft magnetic shields surrounding the AHE reader. We propose reader structures that overcome this challenge. Finally, we discuss the scope for future research to realize AHE readers.

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Noise characterization of ultrasensitive anomalous Hall effect sensors based on Co40Fe40B20 thin films with compensated in-plane and perpendicular magnetic anisotropies

Cited by 9 publications

References 41 publications

Micron-Scale Anomalous Hall Sensors Based on FexPt1−x Thin Films with a Large Hall Angle and near the Spin-Reorientation Transition

Micron-Scale Anomalous Hall Sensors Based on FexPt1−x Thin Films with a Large Hall Angle and near the Spin-Reorientation Transition

A Highly Compressible and Stretchable Carbon Spring for Smart Vibration and Magnetism Sensors

Perspective on nanoscale magnetic sensors using giant anomalous Hall effect in topological magnetic materials for read head application in magnetic recording

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