Chapter 9 Transport properties of ferromagnets

Campbell, I. A.; Fert, A.

doi:10.1016/s1574-9304(05)80095-1

Cited by 167 publications

(201 citation statements)

References 183 publications

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“…13,20 The charge and heat current in each spin channel are related to their respective potential gradient ∇μ ↑,↓ and temperature gradient ∇T as 6 …”

Section: Spin-dependent Seebeck Effect In F/n/f Pillar Spin Valvementioning

confidence: 99%

“…2,12 The spin-dependent Peltier effect, which is the reciprocal of the spin-dependent Seebeck effect, describes heating/cooling of a F/N interface by a spin current. More recently, Flipse et al 7 Although the concept of the spin dependency of the Seebeck coefficient was first discussed by Campbell et al 13 and later used to explain large magnetothermoelectric powers in Co/Cu multilayers, [14][15][16] reports on the Seebeck coefficient polarization P S = S S /S F are relatively scarce. For Ni 80 Fe 20 , a P S of 0.20 has been reported from spin-dependent Seebeck 6 and spin-dependent Peltier 7 measurements.…”

Section: Introductionmentioning

confidence: 99%

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Spin-dependent Seebeck coefficients of Ni80Fe20and Co in nanopillar spin valves

2012

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We have experimentally determined the spin-dependent Seebeck coefficient of permalloy (Ni80Fe20) and cobalt (Co) using nanopillar spin valve devices. The devices were specifically designed to completely separate heat related effects from charge related effects. A pure heat current through the nanopillar spin valve, a stack of two ferromagnetic layers (F) separated by a non-magnetic layer (N), leads to a thermovoltage proportional to the spin-dependent Seebeck coefficient SS=S ↑ −S ↓ of the ferromagnet, where S ↑ and S ↓ are the Seebeck coefficient for spin-up and spin-down electrons. By using a three-dimensional finite-element model (3D-FEM) based on spin-dependent thermoelectric theory, whose input material parameters were measured in separate devices, we were able to accurately determine a spin-dependent Seebeck coefficient of −1.8 µV K −1 and −4.5 µV K −1 for cobalt and permalloy, respectively corresponding to a Seebeck coefficient polarization PS=SS/SF of 0.08 and 0.25, where SF is the Seebeck coefficient of the ferromagnet. The results are in agreement with earlier theoretical work in Co/Cu multilayers and spin-dependent Seebeck and spin-dependent Peltier measurements in Ni80Fe20/Cu spin valve structures.

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“…13,20 The charge and heat current in each spin channel are related to their respective potential gradient ∇μ ↑,↓ and temperature gradient ∇T as 6 …”

Section: Spin-dependent Seebeck Effect In F/n/f Pillar Spin Valvementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spin-dependent Seebeck coefficients of Ni80Fe20and Co in nanopillar spin valves

2012

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“…This is usually associated with suppressed spin-disorder scattering in a magnetic field. 27 For the interpretation of the hysteretic resistivity contribution, we propose a model which is illustrated in Fig. 3͑b͒.…”

Section: Resultsmentioning

confidence: 99%

Magnetoresistive effects in Co/Pd multilayers on self-assembled nanoparticles (invited)

Moser¹,

Kunej²,

Pernau³

et al. 2010

Journal of Applied Physics

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The deposition of Co/Pd multilayers onto self-assembled spherical particles provides a system with unique magnetic properties. The magnetic caps have high perpendicular magnetic anisotropy, are single-domain, and strongly exchange decoupled, but in electrical contact with each other, thus enabling magnetotransport measurements. By applying an external magnetic field, the caps can be switched individually. We systematically studied the magnetoresistance on a two-dimensional cap array consisting of Co/Pd multilayers deposited on particles with a diameter of 200 nm. In the vicinity of the coercive field, a hysteretic resistance peak occurs. It can be explained with the random magnetization configuration of the magnetic caps leading to an increased spin-dependent scattering of the conduction electrons. The underlying mechanism might be comparable to the one causing giant magnetoresistance in granular alloys. For temperatures above 77 K, additional resistivity contributions with high saturation fields are observed, which are tentatively explained by the decreasing size of magnetically ordered parts of the caps with increasing temperature, resulting finally in superparamagnetic behavior in the contact area between neighboring caps.

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“…Together, theory and experiment [26][27][28][29][30] indicate that both a dilute Fe(Cr) alloy and an Fe(Cr)/Cr interface should scatter majority electrons more strongly. In this paper we show that an Fe(Cr)/Cr/Fe(Cr) trilayer displays the two behaviors described in the previous paragraph, namely a normal MR-resistance smallest in the high field P-state, but an inverted current-driven switching-positive current drives the system to the lower resistance P state and negative to the higher resistance AP state Magnetic nanopillars of approximately elliptical shape and dimensions ~ 70 nm x 130 nm were prepared by triode sputtering onto Si substrates.…”

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confidence: 89%

Inverted current-driven switching in Fe(Cr)/Cr/Fe(Cr) nanopillars

AlHajDarwish

Fert

Pratt

et al. 2004

Journal of Applied Physics

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From both theory and experiment, scattering of minority electrons is expected to be weaker than scattering of majority electrons in both dilute Fe(Cr) alloys and at Fe(Cr)/Cr interfaces. We show that Fe(Cr)/Cr/Fe(Cr) trilayer nanopillars display a normal magnetoresistance--i.e., largest resistance at low magnetic fields and smallest at high fields, but an inverted current-driven switching--i.e., positive current flowing from the fixed to the reversing layer switches the trilayer from higher to lower resistance, and negative current switches it from lower to higher.Comment: 3 pages, 3 figs., accepted for J. Magn. Magn. Mat., MMM/Intermag Conf. 200

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Chapter 9 Transport properties of ferromagnets

Cited by 167 publications

References 183 publications

Spin-dependent Seebeck coefficients of Ni80Fe20and Co in nanopillar spin valves

Spin-dependent Seebeck coefficients of Ni80Fe20and Co in nanopillar spin valves

Magnetoresistive effects in Co/Pd multilayers on self-assembled nanoparticles (invited)

Inverted current-driven switching in Fe(Cr)/Cr/Fe(Cr) nanopillars

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