Signal and Noise Aspects of Magnetic Tunnel Junction Sensors for Data Storage

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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“…external magnetic field biasing created on-chip (e.g., using integrated permanent magnets or current line) [77,78] (Fig. 12c, Sect.…”

Section: -P7mentioning

confidence: 99%

Linearization strategies for high sensitivity magnetoresistive sensors

Silva

Leitao

Valadeiro

et al. 2015

Eur. Phys. J. Appl. Phys.

102

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“…Shot noise originates from fluctuations of electrons tunneling through the barrier when a bias is applied across the sensor. Generally, it is assumed that these fluctuations are obeying a Poisson distribution, in which case the noise power can be written as [68,69] …”

Section: Snr Requirements Of a Magnetic Recording Headmentioning

confidence: 99%

Physics and Design of Hard Disk Drive Magnetic Recording Read Heads

Maat¹,

Marley²

2014

Handbook of Spintronics

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Magnetic recording heads always have been on the forefront of technology. A finished magnetic recording head that is manufactured in high volume is the outcome of a coordinated effort of various scientific and engineering disciplines. This chapter will focus on the physics and design of modern magnetic recording read heads. It will explain the underlying concepts of thin film magnetism and electron transport in nanostructures and describe the aspects of device scaling, magnetic stabilization, signal-to-noise considerations, and read-back performance of currently employed tunnel magnetoresistive read heads. An outlook on possible future read-head technologies such as currentperpendicular-to-the-plane giant magnetoresistance, scissor, two-dimensional magnetic recording, and spin-torque sensors will be given. List of Abbreviations

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“…As we have argued above, this increase in resistance will limit the achievable reader SNR. In particular, at high data rates high impedance limits the data rate capability in the play-back process [64,65]. In addition, the impedance mismatch of the preamplifier will also be an issue [65].…”

Section: Resistance Shuntmentioning

confidence: 99%