Spin-valve RAM cell

Tang, D.D.; Wang, P.K.; Speriosu, V. S.; Le, S.; Kung, K.K.

doi:10.1109/20.490329

Cited by 144 publications

(39 citation statements)

References 3 publications

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“…Memory cells with GMR spin valves and GMR sandwiches have been demonstrated, [2][3][4][5] and there are several active programs on developing GMR memories.…”

Section: Introductionmentioning

confidence: 99%

Magnetic tunneling applied to memory (invited)

Daughton¹

1997

Journal of Applied Physics

289

117

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Random access magnetoresistive memories have been designed using anisotropic magnetoresistive ͑AMR͒ material and more recently giant magnetoresistive ͑GMR͒ material. The thin films in these memories have low sheet resistivities ͑about 10 ⍀/sq͒, resulting in cell resistances of 10 to 100 ⍀ at competitive areal densities. High sense currents of a mA or more are required to get signals on the order of a few mV. Spin dependent tunneling ͑SDT͒ devices are intrinsically high impedance, with typical equivalent resistance values of 10 4 -10 9 ⍀ for a square micron area. SDT cells have the potential for signals on the order of 10 mV with lower sense currents, and hence, faster access times than GMR memory. A GMR pseudospin valve memory concept is presented for comparison with SDT memory. Three different design approaches are discussed for SDT memory: ͑1͒ high-density memory arrays similar to those in AMR and GMR memories, ͑2͒ a transistor per cell approach similar to semiconductor dynamic random access memory, and ͑3͒ embedded SDT devices in a flip-flop cell similar to semiconductor static random access memory. The conclusions are: ͑1͒ SDT memory is potentially higher speed than GMR memory, ͑2͒ SDT memory has no area advantage compared with dense GMR memory, and ͑3͒ risks with SDT memory include ͑a͒ processing ultrathin dielectric layers uniformly and reliably that are compatible with integrated circuits and ͑b͒ attaining sufficiently low impedance levels to get a satisfactory signal-to-noise ratio in a small area cell.

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“…Memory cells with GMR spin valves and GMR sandwiches have been demonstrated, [2][3][4][5] and there are several active programs on developing GMR memories.…”

Section: Introductionmentioning

confidence: 99%

Magnetic tunneling applied to memory (invited)

Daughton¹

1997

Journal of Applied Physics

289

117

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“…Other applications have been envisaged, including biosensors, directional sensors and magnetic random access memories [4]. In these applications, the key property of the spinvalve is the relatively large change in resistance that can be obtained under low applied fields at room temperature.…”

Section: Introductionmentioning

confidence: 99%

The contribution of the exchange biased field direction in multilayer thin films to planar Hall resistance

Hung

Quang

Thành

et al. 2007

Physica Status Solidi (b)

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PACS 75.70.Cn Recently, planar Hall effect (PHE) has been widely pursued due to its application potential for biosensors. Planar Hall sensor is based on the anisotropy magnetoresistance and exhibits many advantages, such as large signal-to-noise ratio at low frequencies and high sensitivity at low applied field. The planar Hall resistance (PHR) curve in multilayer thin films with spinvalve structure has pre-eminent sensitivity when compared to single layer and bilayer thin films. In this work, we report a model for PHR calculation that includes the behaviour of single domain basic structure in the external magnetic field. Our results show a qualitative dependence between PHR curves and the angle (β) between the exchange biased field direction and the easy axis of the free layer. As the β increases the sensitivity of the PHR curves also increases. Further, it is shown that our calculation helps to determine the exchange biased field direction.

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“…Exchange anisotropy [1], which is a unidirectional anisotropy appearing in ferromagnetic (F) and antiferromagnetic (AF) dual layers, has been applied in various spin devices, for example, conventional MR [2,3], spin valve magnetic heads [4], MRAM [5], and magnetic media [6], as a crucial technology (exchange bias). In spite of its wide application, a fundamental understanding of the phenomenon is still lacking.…”

Section: Introductionmentioning

confidence: 99%

A compensated/uncompensated independent mechanism of exchange anisotropy appearance using a model with loose coupling in the antiferromagnetic region

Sakurai

2011

Elect Comm in Japan

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SUMMARYSince its discovery, unidirectional anisotropy appearing in exchange coupled ferromagnetic (F)/antiferromagnetic (AF) layers has been used to pin ferromagnetic layers of various spin devices. However, a fundamental understanding is still lacking. The author has already demonstrated a mechanism based on simply assuming a loosely coupled layer in the AF region, without imposing any restrictions on the classical Heisenberg spins, with perfect compensated and uncompensated AF interfaces on the simple cubic (sc) lattice. The difference between compensated and uncompensated is only the F/AF coupling form (spin flop or collinear) interaction, and unidirectional anisotropy does not depend on the compensated or uncompensated case, but appears as a result of introducing loose coupling in the AF region. The unidirectional anisotropy energy does not come from the F/AF interfaces, but from the inner AF coupling defects. As reported in our previous papers, a large decrease in AF interaction from 1/10 to 1/1000 of the usual AF interaction was necessary in order to obtain unidirectional anisotropy in the systems. Correspondence between loose coupling and the defect mode, cell size dependency in the fcc system, and thickness dependency are topics for future investigation.

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Spin-valve RAM cell

Cited by 144 publications

References 3 publications

Magnetic tunneling applied to memory (invited)

Magnetic tunneling applied to memory (invited)

The contribution of the exchange biased field direction in multilayer thin films to planar Hall resistance

A compensated/uncompensated independent mechanism of exchange anisotropy appearance using a model with loose coupling in the antiferromagnetic region

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