Optimizing the giant magnetoresistance of NiFe/Cu/Co pseudo spin-valves prepared by magnetron sputtering

Paul, Amitesh; Damm, Thorsten; Bürgler, D. E.; Stein, S.; Kohlstedt, H.; Grünberg, P.

doi:10.1063/1.1563056

Cited by 20 publications

(13 citation statements)

References 16 publications

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“…For Ni films prepared under 0.5 Torr, with film thickness increasing from 20–40 nm, grain size and porous structure increases. A similar type of work is presented in a recent report where variation of grain size, and clustering of grains under high pressure has been reported using atomic force microscopy (AFM) topography analysis …”

Section: Resultsmentioning

confidence: 56%

Pulsed PECVD for Low‐temperature Growth of Vertically Aligned Carbon Nanotubes

Baro

Gogoi

Pal

et al. 2014

Chemical Vapor Deposition

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Pulsed plasma-enhanced (PE)CVD is used for the growth of vertically aligned multiwall carbon nanotubes (CNTs) at a low temperature range of 350-490°C. A pulsed plasma is generated by the application of a rectangular negative pulse to the substrate electrode with an on time of 4.5 ms, off time of 5.5 ms, duty cycle of 45%, and pulse repetition frequency of 100 kHz. CNTs are synthesized from Ni catalyst film of 20-40 nm thickness deposited on a silicon substrate under pressures of 0.01 and 0.5 Torr by magnetron sputtering. The effect of Ni catalyst film morphology on low temperature growth of CNTs by pulsed PECVD is studied. It is found that CNTs grown from Ni catalyst films depend on the process pressure employed to prepare the film by magnetron sputtering. A comparison with the direct current (DC) discharge-produced CNTs reveals that the growth rate of pulsed plasma-produced CNTs is two times higher. CH species density is studied using optical emission spectroscopy (OES) by an actinometrical approach, which shows that DC discharge plasma has a higher CH concentration, but still has a lower growth rate. Further, it is observed that using pulsed plasma, growth of CNTs is possible at temperatures down to 350°C, whereas in the case of DC discharge plasma, CNTs growth is possible only at temperatures down to 450°C in the present experimental set-up. Possible reasons for the better performance of pulsed plasma in respect of growth rate and low temperature growth are discussed.

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Section: Resultsmentioning

confidence: 56%

Pulsed PECVD for Low‐temperature Growth of Vertically Aligned Carbon Nanotubes

Baro

Gogoi

Pal

et al. 2014

Chemical Vapor Deposition

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“…The reduced energy decreases surface mobility of the deposited adatoms. The broadening of the angular distribution leads to intergrain shading, which results in a morphology with clusters and voids on a length scale larger than the grain size [27]. Moreover, low deposition rate facilitates an inclusion of gas molecules in growing film.…”

Section: Resultsmentioning

confidence: 99%

“…It is known, that the magnetostatic energy of the domain wall is proportional to the angular dispersion of anisotropy [27,28], thus increase of the anisotropy dispersion should lead to an increase of coercive force. However, the sample prepared at the deposition rate of 18 nm/min has maximum anisotropy dispersion, but minimum coercivity (Table 1).…”

Section: Resultsmentioning

confidence: 99%

Study of the effect of the deposition rate and seed layers on structure and magnetic properties of magnetron sputtered FeNi films

Svalov

Asensio

Членова

et al. 2015

Vacuum

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“…For some applications a key problem in PSV is the choice of appropriate ferromagnetic materials for the hard and soft layers to ensure a high difference in the switching fields and large magnetoresistance (MR) ratios. There have been various attempts to optimize PSV by increasing the difference in coercivity [3], by changing the layer thickness [4], or by optimizing sputtering technology [5]. In the present study we show how to optimize the switching fields and MR ratio in NiO/Co/Cu/Co PSV by changing the thickness of constituent layers.…”

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confidence: 74%

Pseudo spin‐valve structures with NiO/Co as a hard magnetic layer

Dubowik

Stobiecki

Szymański

et al. 2004

Physica Status Solidi (b)

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PACS 75.47. De, 75.70.Cn A key problem in some applications of pseudo spin-valve structures (PSV) is the choice of appropriate materials for soft and hard ferromagnetic layers and their thickness to ensure a high difference in the switching fields. We show that this can be achieved using a NiO/Co structure as a hard magnetic layer. By varying the thickness of the constituent layers, good symmetrical switching characteristics have been shown in PSV structures with NiO/Co as a hard magnetic layer. The most important features of our PSV structures with suitable selected thickness of particular layers are: a relatively high value of GMR amplitude (up to 9% at RT) due to a possible electron specular reflection at the NiO/Co interfaces, a high coercivity (~500 Oe) of hard magnetic layer resulted from a specific interaction of a 15 nm thick antiferromagnetic NiO with a 2 nm thick Co layer, nearly symmetrical magnetoresistance transfer curves MR(H) due to negligible unidirectional anisotropy field of NiO/Co bilayer with NiO thickness <15 nm. 1 Introduction Pseudo spin-valves (PSV) comprising soft and hard ferromagnetic layers separated by a nonferromagnetic spacer are interesting due to their potential application in magnetoresistive sensors and magnetic random access memories [1]. The soft magnetic layer switches at a smaller external field than the hard layer, which gives rise to antiparallel alignment of magnetization correlated with a high resistance state [2]. For some applications a key problem in PSV is the choice of appropriate ferromagnetic materials for the hard and soft layers to ensure a high difference in the switching fields and large magnetoresistance (MR) ratios. There have been various attempts to optimize PSV by increasing the difference in coercivity [3], by changing the layer thickness [4], or by optimizing sputtering technology [5]. In the present study we show how to optimize the switching fields and MR ratio in NiO/Co/Cu/Co PSV by changing the thickness of constituent layers. A stress is put on optimizing the magnetic characteristics of the Co layer exchange coupled (pinned) to NiO so that the NiO/Co bilayer forms the hard magnetic layer. In particular, the influence of NiO is the most important since NiO is known to induce unidirectional anisotropy and to enhance the coercive field of the pinned Co layer [6] due to a specific ferromagnetic/antiferromagnetic coupling. Moreover, there is an increase of GMR effect due to specular electron reflection at NiO/Co interface [7].

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Optimizing the giant magnetoresistance of NiFe/Cu/Co pseudo spin-valves prepared by magnetron sputtering

Abstract: Articles you may be interested inEffects of grain cluster size on coercivity and giant magnetoresistance of NiFe/Cu/CoFe/Cu/NiFe pseudo spin valves Appl.

Cited by 20 publications

References 16 publications

Pulsed PECVD for Low‐temperature Growth of Vertically Aligned Carbon Nanotubes

Pulsed PECVD for Low‐temperature Growth of Vertically Aligned Carbon Nanotubes

Study of the effect of the deposition rate and seed layers on structure and magnetic properties of magnetron sputtered FeNi films

Pseudo spin‐valve structures with NiO/Co as a hard magnetic layer

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