Low-Frequency Noise in MgO Magnetic Tunnel Junctions: Hooge's Parameter Dependence on Bias Voltage

Almeida, José; Wiśniowski, P.; Freitas, P. P.

doi:10.1109/tmag.2008.2002604

Cited by 41 publications

(43 citation statements)

References 12 publications

(25 reference statements)

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“…Until now, a few reports have been published on the low frequency noise in DMTJs with a thick free layer 12,20 but their TMR ratio of around 80%-120% is considerably less than we report here. Earlier studies of MgO DMTJs did not produce high TMR because the middle CoFeB layer remains amorphous after annealing.…”

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confidence: 72%

“…It has been previously reported that 1 / f noise dominates the low frequency response of MTJs. [15][16][17][18][19][20][21][22][23] The 1 / f noise can be characterized by a noise magnitude parameter ␣ = AfS V / V 2 , where A is the junction area, f is the frequency, S V is the noise power spectrum density, and V is the applied bias. 15 Recently, Guerrero et al 24 suggested that 1 / f noise can be greatly reduced in field sensors, when a large number of MTJs are connected either in series or in parallel.…”

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confidence: 99%

“…Earlier studies of MgO DMTJs did not produce high TMR because the middle CoFeB layer remains amorphous after annealing. [10][11][12]20 The adjacent MgO barriers cannot absorb boron, which maintains the amorphous nature of CoFeB. 25 Here we investigate the low frequency noise in DMTJs, with TMR ratios as high as 222% for symmetric MgO layers and 250% for asymmetric MgO layers at room temperature.…”

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confidence: 99%

“…[10][11][12]20 The adjacent MgO barriers cannot absorb boron, which maintains the amorphous nature of CoFeB. 25 Here we investigate the low frequency noise in 20 as free layer with high temperature postannealing, which was recently reported to improve the TMR ratio in DMTJs. 13 We also discuss the probability of applying DMTJs as magnetic field sensors, based on their noise characteristics.…”

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confidence: 99%

“…1 inset͒, with the AP state being much noisier than the P state. [15][16][17][19][20][21] Figure 2͑a͒ shows the T a dependence of ␣ in the P state ͑␣ P ͒ for representative DMTJs and SMTJs. The ␣ P value decreases with T a for both types, which reflects a gradual improvement of the interfaces between the ferromagnetic layers and the MgO tunnel barrier.…”

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1 / f noise in MgO double-barrier magnetic tunnel junctions

Diao

Feng

et al. 2011

Applied Physics Letters

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Low frequency noise has been investigated in MgO double-barrier magnetic tunnel junctions ͑DMTJs͒ with tunneling magnetoresistance ͑TMR͒ ratios up to 250% at room temperature. The noise shows a 1 / f frequency spectrum and the minimum of the noise magnitude parameter is 1.2ϫ 10 −10 m 2 in the parallel state for DMTJs annealed at 375°C. The bias dependence of noise and TMR suggests that DMTJs with MgO barriers can be useful for magnetic field sensor applications. © 2011 American Institute of Physics. ͓doi:10.1063/1.3562951͔The large tunneling magnetoresistance ͑TMR͒ in MgO barrier magnetic tunnel junctions ͑MTJ͒ has greatly improved the performance of spintronic devices, such as magnetic random access memories ͑MRAMs͒, sensors, and logic devices. [1][2][3][4][5][6][7][8][9] The record room temperature TMR of 604% is found in single-barrier MTJs ͑SMTJs͒ with a pseudo spin valve stack, 6 which is close to the theoretical maximum. 1,2 However, the TMR ratio in an MTJ falls off with increasing bias. 10 Double barrier MTJs ͑DMTJs͒ offer TMR of 105%-212% at room temperature 10-13 but bias dependence of TMR is reduced because the applied voltage is divided over two single barriers. This helps to preserve the high TMR ratio at high bias. 10 A high bias is needed to inject a sufficiently large critical current to facilitate spin transfer torque ͑STT͒ switching in magnetic nanopillars with MgO barriers, which is the basis for high-speed non-volatile STT-MRAM. 14 In conventional DMTJs with a thick free layer, TMR is often lower than that in SMTJs. [10][11][12][13] However, a DMTJ can potentially improve the signal-to-noise ratio of a magnetic field sensor due to the increase in output voltage compared to an SMTJ. Hence, the low frequency noise of DMTJs is worth exploring, in comparison with that of SMTJs. It has been previously reported that 1 / f noise dominates the low frequency response of MTJs. [15][16][17][18][19][20][21][22][23] The 1 / f noise can be characterized by a noise magnitude parameter ␣ = AfS V / V 2 , where A is the junction area, f is the frequency, S V is the noise power spectrum density, and V is the applied bias. 15 Recently, Guerrero et al. 24 suggested that 1 / f noise can be greatly reduced in field sensors, when a large number of MTJs are connected either in series or in parallel. However, devices constructed with a large number of MTJs may lack integrity and suffer from a much higher chance of failure. DMTJs may be able to halve the 1 / f noise without these drawbacks, opening up a way to reduce the noise.Until now, a few reports have been published on the low frequency noise in DMTJs with a thick free layer 12,20 but their TMR ratio of around 80%-120% is considerably less than we report here. Earlier studies of MgO DMTJs did not produce high TMR because the middle CoFeB layer remains amorphous after annealing. [10][11][12]20 The adjacent MgO barriers cannot absorb boron, which maintains the amorphous nature of CoFeB. 25 Here we investigate the low frequency noise in DMTJs, with TMR ratios as high...

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confidence: 99%

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confidence: 99%

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confidence: 99%

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1 / f noise in MgO double-barrier magnetic tunnel junctions

Diao

Feng

et al. 2011

Applied Physics Letters

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Tunneling Magnetoresistance (TMR) Materials and Devices for Magnetic Sensors

2022

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Vertical Photodetectors Based on In Situ Aligned Single‐crystalline PbS Nanocuboids Sandwiched between Graphene Electrodes

Yang

Nie

et al. 2023

Advanced Optical Materials

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Lead sulfide (PbS), a classical narrow‐bandgap material, has manifested itself as a reliable choice for short‐wave infrared (SWIR) detection with high sensitivity. The primary efforts of optimizing PbS‐based photodetectors rely on discovering new low‐dimensional morphology and designing delicate device architecture, which may raise problems in the synergistic improvement of response speed, sensitivity, and response region. Herein, a graphene‐PbS nanocuboids‐graphene vertical photodetector is reported, fabricated by in situ electrochemical growth of monocrystalline PbS nanocuboids on graphene using an electrochemical technique. Under illumination, the surface states of PbS nanocuboids trap photogenerated holes and form a photovoltage, which widens the conductive region in the channel. This photogating effect contributes to the photocurrent and renders the device with high responsivity. Moreover, the highly crystalline PbS nanocuboids serve as excellent vertical channels, allowing a fast speed to be achieved. At room temperature, the device shows a responsivity of ≈130 A W−1 at 2700 nm, an external quantum efficiency of ≈6000%, a detectivity of 3 × 109 cm Hz1/2 W−1 (@1 kHz), and response/recovery speeds of 15/42 ms. This vertically integrated device, composed of PbS nanocuboids and graphene, offers a promising approach to complementary metal oxide semiconductor (CMOS)‐compatible SWIR detection, thus opening up an avenue to tailor device performance by exploiting the anisotropic morphology of nanomaterials.

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Low-Frequency Noise in MgO Magnetic Tunnel Junctions: Hooge's Parameter Dependence on Bias Voltage

Cited by 41 publications

References 12 publications

1 / f noise in MgO double-barrier magnetic tunnel junctions

1 / f noise in MgO double-barrier magnetic tunnel junctions

Tunneling Magnetoresistance (TMR) Materials and Devices for Magnetic Sensors

Vertical Photodetectors Based on In Situ Aligned Single‐crystalline PbS Nanocuboids Sandwiched between Graphene Electrodes

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