Magnetoresistance of granular ferromagnets

Gerber, A.; Milner, A.; Groisman, Bella; Karpovsky, Mark G.; Gladkikh, A.; Sulpice, A.

doi:10.1103/physrevb.55.6446

Cited by 96 publications

(65 citation statements)

References 19 publications

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“…The AHE voltage is then proportional to magnetic moment of individual magnetic clusters averaged over the volume of the sample. Similar results have been obtained by AHE measurements of fcc Co clusters prepared by LECBD, embedded in a Pt matrix [46,47]. The H C⊥ values and their temperature dependence obtained by this method in our Co-Pt granular films perfectly match those identified by SQUID magnetometry in Fig.…”

Section: Measurements Of Hall Voltage In Magnetic Materials Have An Asupporting

confidence: 77%

“…The AHE arises from spin dependent scattering mechanisms, so that correlation between the AHE and the magnetization enables the use of the Hall voltage measurement for the study of magnetic properties of materials in conditions hardly accessible by other techniques [46]. Indeed, it is a method frequently used to study the magnetic properties of thin films exhibiting PMA.…”

Section: Measurements Of Hall Voltage In Magnetic Materials Have An Amentioning

confidence: 99%

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Structural and magnetic properties of granular Co-Pt multilayers with perpendicular magnetic anisotropy

et al. 2014

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We present a study of granular Co-Pt multilayers by means of high-resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS), SQUID-based magnetic measurements, anomalous Hall effect (AHE), and x-ray magnetic circular dichroism (XMCD). We describe these granular films as composed of particles with a pure cobalt core surrounded by an alloyed Co-Pt interface, embedded in a Pt matrix. The alloy between the Co and Pt in these granular films, prepared by room temperature sputter deposition, results from interdiffusion of the atoms. The presence of this alloy gives rise to a high perpendicular magnetic anisotropy (PMA) in the granular films, as consequence of the anisotropy of the orbital moment in the Co atoms in the alloy, and comparable to that of highly-ordered CoPt L1 0 alloy films. Their magnetic properties are those of ferromagnetically coupled particles, whose coupling is strongly temperature dependent: at low temperatures, the granular sample is ferromagnetic with a high coercive field; at intermediate temperatures the granular film behaves as an amorphous asperomagnet, with a coupling between the grains mediated by the polarized Pt, and at high temperatures, the sample has a superparamagnetic behavior. The coupling/decoupling between the grains in our Co-Pt granular films can be tailored by variation of the amount of Pt in the samples.

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Section: Measurements Of Hall Voltage In Magnetic Materials Have An Asupporting

confidence: 77%

Section: Measurements Of Hall Voltage In Magnetic Materials Have An Amentioning

confidence: 99%

Structural and magnetic properties of granular Co-Pt multilayers with perpendicular magnetic anisotropy

et al. 2014

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“…4 presents a linear correlation between the insulator scattering contributions to EHE resistivity and linear resistivity, found in granular Ni-SiO 2 mixtures with a relatively low concentration of SiO 2 [14]. At higher concentrations of SiO 2 (about 50% depending on deposition conditions [29,30] the system approaches the metal -insulator transition with resistivity diverging above 1Ωcm and the saturated Hall resistivity reaching 200 µΩcm [13]. For 1 µm thick films the field sensitivity is about 10 Ω/T.…”

Section: Insulating Impurities In Ferromagnetic Hostmentioning

confidence: 99%

Perspective of Spintronics Applications Based on the Extraordinary Hall Effect

Gerber¹,

Riss²

2008

Journal of Nanoelectronics and Optoelectronics

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Extraordinary Hall effect (EHE) is a spin-dependent phenomenon that generates voltageproportional to magnetization across a current carrying magnetic film. Magnitude of the effect can be artificially increased by stimulating properly selected spin-orbit scattering events. Already achieved sensitivity of the EHE-based sample devices exceeds 1000 Ω/T, which surpasses the sensitivity of semiconducting Hall sensors. Linear field response, thermal stability, high frequency operation, sub-micron dimensions and, above all, simplicity, robustness and low cost manufacture are good reasons to consider a wide scale technological application of the phenomenon for magnetic sensors and memory devices.2 Anisotropic magnetoresistance [1,2], planar Hall effect [3,4], spin-dependent tunneling [5,6] and the extraordinary or anomalous Hall effect (EHE) [7,8] are spin-dependent electronic transport phenomena known for many years. However, it is the discovery of the giant magnetoresistance (GMR) [9,10] that gave birth to the term spintronics and triggered a world-wide outburst of the spin-related research. Extraordinary Hall Effect (EHE) in magnetic materials was discovered more than a century ago [7], extensively studied both theoretically and experimentally [8], and left out of the mainstream research for the last thirty years. The possibility to use the effect for technical applications, such as magnetic sensors and nonvolatile magnetic random access memories (MRAM), has been mentioned more than three decades ago [11], but no significant progress was reported until recently. A probable reason for this is that although EHE in bulk magnetic materials can be significantly higher than the ordinary Hall effect in normal metals, its magnitude remained far beyond the sensitivity of semiconductors and magnetic sensors based on the anisotropic magnetoresistance [12]. The renewed interest in EHE has only recently arisen when some recipes to enhance the effect were found [13][14][15].The Hall effect in magnetic materials is commonly described [8,16] by the phenomenological equationwhere ρ H is the Hall resistivity, B, H and M are components of the magnetic induction, applied field and magnetization normal to the film plane, and D is the demagnetization factor. R 0 is the ordinary Hall coefficient related to the Lorentz force acting on moving charge carriers. R EHE , the extraordinary Hall coefficient, is associated with a break of the right-left symmetry at spin-orbit scattering in magnetic materials.. Demagnetization factor D is equal to 1 when field is applied perpendicular to a homogeneous magnetic film. In this case Eq.1 is simplified toVoltage measured between Hall contacts located perpendicular to the direction of an electric current is given by:where I is current and t thickness of the film. Fig.1 presents a typical field dependence of the Hall resistance (in a 4 nm thick Ni film at room temperature with field applied normal to the film plane.Magnetization normal to the film increases with field till saturation at about ±0.2 T. The EH...

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“…Путем изменения проводи-мости самой матрицы, а также размеров и концентраций микронаночастиц, можно эффективно управлять знаком, величиной и видом магнитополевой зависимости магне-тосопротивления. Таким способом можно получать ком-позиты, проявляющие гигантский, колоссальный, тун-нельный, изотропный или анизотропный по характеру магниторезистивный эффект (МРЭ), и выявить основ-ные физические механизмы процесса протекания тока в них [12][13][14].…”

Section: (поступило в редакцию 29 ноября 2016 г в окончательной редаunclassified

Магнитные свойства композиционных материалов на основе твердого раствора типа (CuInSe-=SUB=-2-=/SUB=-)-=SUB=-1-x-=/SUB=-(МеSe)-=SUB=-x-=/SUB=- (Ме = Mn, Fe) и полиэтилена

Samedova

Gasanli

2018

Журнал Технической Физики

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Magnetoresistance of granular ferromagnets

Cited by 96 publications

References 19 publications

Structural and magnetic properties of granular Co-Pt multilayers with perpendicular magnetic anisotropy

Structural and magnetic properties of granular Co-Pt multilayers with perpendicular magnetic anisotropy

Perspective of Spintronics Applications Based on the Extraordinary Hall Effect

Магнитные свойства композиционных материалов на основе твердого раствора типа (CuInSe-=SUB=-2-=/SUB=-)-=SUB=-1-x-=/SUB=-(МеSe)-=SUB=-x-=/SUB=- (Ме = Mn, Fe) и полиэтилена

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