Nanoscale magnetic tunnel junction sensors with perpendicular anisotropy sensing layer

Zeng, Zhongming; Amiri, Pedram Khalili; Katine, J. A.; Langer, J.; Wang, K. L.; Jiang, Hong-Wen

doi:10.1063/1.4744914

Cited by 50 publications

(38 citation statements)

References 19 publications

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“…The latter presents simultaneously both types of responses, sharp hysteretic ones with TMR values up to ∼200% (t > t critical ) and linear responses with TMR values down to 40%, translating the thin CoFeB evolution from the ferromagnetic to the SPMlike regime (t ≤ t critical ). This transition is also illustrated in the inset of Figure 20a with the abrupt drop in coercive field at t critical ∼ 1.45 nm which is in accordance with other reported values [79][80][81][92][93][94]. Tsai et al estimated ∼23 nm as the average lateral size of the ferromagnetic particles at the sensing layer [94] while Shen et al obtained 40-120 nm [95] which for the given t critical implies that the clusters have a pancake-like shape.…”

Section: -P11supporting

confidence: 78%

“…The latter can result in a linear response to in-plane magnetic fields [80,81]. Figure 20a shows the progress of patterned MTJ transfer curves with decreasing sensing layer thickness.…”

Section: -P11mentioning

confidence: 99%

“…20a). Zeng et al reports wider ranges obtained with nano MTJs, with optimum values of μ 0 ΔH linear = 60 mT and 0.2%/mT [80].…”

Section: -P11mentioning

confidence: 99%

“…2.2); iii. reduction of the sensing layer thickness until the superparamagnetic limit (e.g., CoFeB thicknesses below 1.5 nm) [79][80][81] (Fig. 12d, Sect.…”

Section: -P7mentioning

confidence: 99%

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Linearization strategies for high sensitivity magnetoresistive sensors

Silva

Leitao

Valadeiro

et al. 2015

Eur. Phys. J. Appl. Phys.

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Abstract. Ultrasensitive magnetic field sensors envisaged for applications on biomedical imaging require the detection of low-intensity and low-frequency signals. Therefore linear magnetic sensors with enhanced sensitivity low noise levels and improved field detection at low operating frequencies are necessary. Suitable devices can be designed using magnetoresistive sensors, with room temperature operation, adjustable detected field range, CMOS compatibility and cost-effective production. The advent of spintronics set the path to the technological revolution boosted by the storage industry, in particular by the development of read heads using magnetoresistive devices. New multilayered structures were engineered to yield devices with linear output. We present a detailed study of the key factors influencing MR sensor performance (materials, geometries and layout strategies) with focus on different linearization strategies available. Furthermore strategies to improve sensor detection levels are also addressed with best reported values of ∼40 pT/ √ Hz at 30 Hz, representing a step forward the low field detection at room temperature.

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Section: -P11supporting

confidence: 78%

“…The latter can result in a linear response to in-plane magnetic fields [80,81]. Figure 20a shows the progress of patterned MTJ transfer curves with decreasing sensing layer thickness.…”

Section: -P11mentioning

confidence: 99%

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Linearization strategies for high sensitivity magnetoresistive sensors

Silva

Leitao

Valadeiro

et al. 2015

Eur. Phys. J. Appl. Phys.

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“…To obtain these characteristics and to suppress hysteresis in magnetoresistance (MR) curves, MTJs with spin-valve-type structures of CoFeB sensing layers showing perpendicular magnetic anisotropy (PMA) have been investigated. [1][2][3] We have also reported that the MTJs of CoFeB sensing layers of various thicknesses, which show PMA at the MgO/CoFeB interface, 4 can suppress the hysteresis. 3 Ta capping layers have been applied to these reported MTJs, in which CoFeB sensing layers have only one interface with MgO films, and the characteristics of the MTJs of the sensing layers showing partial PMA strongly depend on the thickness of the sensing layer.…”

Section: Introductionmentioning

confidence: 91%

Magnetic tunnel junctions for magnetic field sensor by using CoFeB sensing layer capped with MgO film

Takenaga

Tsuzaki

Yoshida

et al. 2014

Journal of Applied Physics

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High‐Performance Flexible Magnetic Tunnel Junctions for Smart Miniaturized Instruments

et al. 2018

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MANUSCRIPT TEXT IntroductionFlexible electronics has become an established field that has seen tremendous developments over the last years. [1][2][3][4][5][6][7][8][9][10] The unique capability to adjust the geometry of devices to curved surfaces or surfaces of changing shape provides vast advantages over conventional electronics on rigid substrates. Hence, flexible printed circuit boards have already become an industrial standard for medical implants or consumer electronics [11][12][13][14] , where the main requirements are: large area, extreme thinness, and conformity to curved surfaces. The recent progress of organic [6,15,16] as well as inorganic [14,17,18] electronics, which are basically performed using printing or thin film technologies, has been very beneficial for the improvement of flexing electronic devices. In combination with other methods like screen or inkjet printing, novel concepts for flexible electronics have been developed for several applications including displays, [19] organic light-emitting diodes, [20] sensors, [21][22][23][24][25] radio frequency identification tags, [26][27][28] and organic solar cells. [29] Meanwhile, there are increasing activities on flexible magnetic field sensors and magnetoelectronics, [30,31] due to ubiquitous use of such kinds of devices. [18,32] By now, high-performance magnetic sensors based on the giant magnetoresistive (GMR) effect and the tunneling magnetoresistive (TMR) effect are mainly prepared using thin film fabrication technologies. [18,[33][34][35][36][37][38][39] This method allows for fabricating extremely sensitive magnetic sensors, especially on Si substrates, and it would therefore be a desirable solution to flex the silicon substrate, where the magnetic elements are fabricated onto. Magnetic tunnel junctions (MTJs) are of particular interest, because they constitute the main component of diverse spintronic devices such as spin-transfer oscillators, magnetic sensors, hard-disk-drive read-heads or Magnetic Random Access Memories. [40] MTJs are made of a magnetic multilayer thin film material. For sensor applications, the low power consumption [41] , high sensitivity and small size make them an attractive option. MTJs with amorphous Al-oxide barriers exhibit TMR ratios below 100 %. This can be improved by using (001)-oriented MgO barriers, achieving TMR ratios over 150 % at room temperature. [42][43][44] These high values can be exploited to design very sensitive TMR sensors, [45][46][47][48][49][50] such as biomagnetic field sensors [51] . They show an important change in resistance versus the magnetic field than other sensors such as those utilizing the anisotropic magnetoresistance or giant magnetoresistance. [52][53][54] Compared to conventionally used Hall effect and AMR sensors, a TMR sensor can also have higher sensitivity, lower power consumption [41] , better temperature stability and, in particular, compared to an AMR sensor, a wider linear range can be obtained. [54] Flexible MTJ devices have been reported with alumina [37,39] and MgO t...

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Nanoscale magnetic tunnel junction sensors with perpendicular anisotropy sensing layer

Cited by 50 publications

References 19 publications

Linearization strategies for high sensitivity magnetoresistive sensors

Linearization strategies for high sensitivity magnetoresistive sensors

Magnetic tunnel junctions for magnetic field sensor by using CoFeB sensing layer capped with MgO film

High‐Performance Flexible Magnetic Tunnel Junctions for Smart Miniaturized Instruments

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