Magnetotransport and electronic noise in superparamagnetic magnetic tunnel junctions

Zhang, Yiou; He, Guanyang; Zhang, Xixiang; Xiao, Gang

doi:10.1063/1.5110715

Cited by 12 publications

(7 citation statements)

References 27 publications

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“…The effective PMA coefficient is given by

(

is the interfacial PMA,

the vacuum permeability and

the saturation magnetization), which is expected to decrease with increasing t FePt . On the other hand, the decrease in the Hall slope with decreasing t FePt in the low t FePt range can be understood from the possible transition to the paramagnetic or superparamagnetic phase, as observed in other magnetic thin films [ 11 , 43 ]. The largest Hall slope among all these samples reaches 104.9 µΩ cm/T, in an as-grown multilayer of MgO(1.6)/Fe 0.48 Pt 0.52 (1.25)/MgO(1.6)/TaO x (1.0).…”

Section: Resultsmentioning

confidence: 99%

“…This method provides an accurate measurement of the sensitivity, while the sensitivity derived from the slope of the Hall curve may be overestimated [ 37 , 38 , 39 ]. Noise measurements using a two-channel cross correlation method [ 40 ] have also been described in detail in our previous works [ 2 , 5 , 11 ]. In both measurements, we applied a 1 mA current to Hall crosses.…”

Section: Methodsmentioning

confidence: 99%

“…The field detectability of anomalous Hall sensors is not as good as magneto-resistive (MR) sensors with large sensing areas [ 2 , 8 , 9 , 10 , 11 ]. However, normalized by sensing areas, anomalous Hall sensors perform comparably or better over MR sensors in micro-sensing applications where a high spatial resolution is desired.…”

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.

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“…The effective PMA coefficient is given by

(

is the interfacial PMA,

the vacuum permeability and

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

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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“…The optimization of the MR stack structure is the most straightforward way to increase the sensitivity of the MR sensors while maintaining moderate linearity. For example, several new TMR structures have been proposed for sensing applications such as the superparamagnetic free layer [155] and two pinned antiferromagnetic electrodes [156]. Other sensitivity improvement from the circuitry level have also been employed such as integrating multiple MR sensors into a Wheatstone Bridge [157], connecting multiple MR sensors in series [158], and the application of MFCs.…”

Section: Discussionmentioning

confidence: 99%

Advances in Magnetoresistive Biosensors

Saha

et al. 2019

Micromachines

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Magnetoresistance (MR) based biosensors are considered promising candidates for the detection of magnetic nanoparticles (MNPs) as biomarkers and the biomagnetic fields. MR biosensors have been widely used in the detection of proteins, DNAs, as well as the mapping of cardiovascular and brain signals. In this review, we firstly introduce three different MR devices from the fundamental perspectives, followed by the fabrication and surface modification of the MR sensors. The sensitivity of the MR sensors can be improved by optimizing the sensing geometry, engineering the magnetic bioassays on the sensor surface, and integrating the sensors with magnetic flux concentrators and microfluidic channels. Different kinds of MR-based bioassays are also introduced. Subsequently, the research on MR biosensors for the detection of protein biomarkers and genotyping is reviewed. As a more recent application, brain mapping based on MR sensors is summarized in a separate section with the discussion of both the potential benefits and challenges in this new field. Finally, the integration of MR biosensors with flexible substrates is reviewed, with the emphasis on the fabrication techniques to obtain highly shapeable devices while maintaining comparable performance to their rigid counterparts.

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“…Harmonic decomposition of V z into V z,n is meaningful for the odd components since the nonlinear characteristics of MR sensor resemble Langevin function. 18) However, V z,n with low signal integrity and small magnitude for n = 2, 4, 6, … is inconvenient for the modulated MPI.…”

mentioning

confidence: 99%

Magnetic particle imaging using linear magnetization response-driven harmonic signal of magnetoresistive sensor

Trisnanto

Kasajima

Akushichi

et al. 2021

Appl. Phys. Express

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We achieved a harmonic-rich signal from linear magnetization responses of magnetic nanoparticles under 40 μT/μ 0 excitation field to facilitate magnetic particle imaging (MPI). In contrast, large harmonic responses are typically attributed to the nonlinear field-dependent magnetization characteristics of the particles, thus questioning technical and clinical issues toward a human-sized MPI scanner. By using a magnetoresistive sensor, we propose a strategy to exploit the linear responses of the tracers at low field regime where the standard MPI may struggle with spatial signal decoding. The achieved high-contrast images of a solid ferucarbotran phantom bring new expectation toward clinical use of MPI.

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Magnetotransport and electronic noise in superparamagnetic magnetic tunnel junctions

Cited by 12 publications

References 27 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

Advances in Magnetoresistive Biosensors

Magnetic particle imaging using linear magnetization response-driven harmonic signal of magnetoresistive sensor

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