Magnetic properties of Pd/Co multilayer films studied by Hall effect

Kim, Sangrok; Lee, Seong Rae; Chung, Jin Duck

doi:10.1063/1.352643

Cited by 23 publications

(9 citation statements)

References 10 publications

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“…Since Co/Pd is one of the promising candidates for perpendicular magnetic recording technology, [3][4][5] there are several AHE studies on thin Co-Pd alloys and {Co/Pd} n multilayers. In chronological order, Kim et al 10 explored the Pd thickness dependence of the AHE of {Co/Pd} multilayers prepared by thermal evaporation at room temperature and observed a polarity change of the AHE between 4 and 5 monolayers of Pd for a fixed Co thickness of one monolayer. It was speculated that this can be attributed to a change of the position of the Fermi level with increasing Pd thickness.…”

mentioning

confidence: 99%

Temperature and Co thickness dependent sign change of the anomalous Hall effect in Co/Pd multilayers: An experimental and theoretical study

Keskin

Aktaş

Schmalhorst

et al. 2013

Applied Physics Letters

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The anomalous Hall effect in ultra-thin {Co 0.3 nm /Pd 0.5 nm } n multilayers has been investigated recently with respect to surface and interface contributions [Guo et al., Phys. Rev. B 86, 104433 (2012)]. In this work, we observe a Co thickness and temperature dependent sign change also for {Co 0.20-0.55 nm /Pd 1.5nm or 1.8 nm } 9x multilayers, e.g., in layer stacks with considerably thicker Pd layers and hence lower resistivity. The thickness dependent behavior can be reproduced by ab initio calculations of the Hall conductivity, for which only interfacial and bulk contributions play a role. V

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confidence: 99%

Temperature and Co thickness dependent sign change of the anomalous Hall effect in Co/Pd multilayers: An experimental and theoretical study

Keskin

Aktaş

Schmalhorst

et al. 2013

Applied Physics Letters

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“…There are several reports on the reversal of the EHE polarity, particularly in Co-based materials. The phenomenon was observed in CoPd alloys [12] and multilayers [13,14] when concentration or a relative thickness ratio between the components was changed, and when a layer of FeMn antiferromagnet was added [15]. It was suggested [13] that the change of the position of Fermi level and, therefore shift of the majority carriers from electrons to holes, is the reason for the change of EHE polarity.…”

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confidence: 99%

Reversal of the extraordinary Hall effect polarity in thin Co/Pd multilayers

Rosenblatt

Karpovski

Gerber

2010

Applied Physics Letters

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Ramat Aviv, 69978 Tel Aviv Israel Thin Co/Pd multilayers, with room temperature perpendicular anisotropy and an enhanced surface scattering, were studied for the possible use in the extraordinary Hall effect (EHE) -based magnetic memory devices. Polarity of the EHE signal was found to change from negative in thick samples to positive in thin ones. Reversal of EHE sign was also observed in thick samples with aging. The effect is argued to be related to the dominance of surface scattering having the EHE polarity opposite to that of the bulk. PACS: 73.50.-h, 75.50.Ss, 75.70.Cn Extraordinary or anomalous Hall effect (EHE) was discovered about 130 years ago, however, discussion of its practical application only started recently when it was demonstrated [1] that a relatively small EHE coefficient of bulk ferromagnets can be boosted by stimulating proper scattering events. The addition of insulating impurities into bulk transition metals [2] or the increase of surface scattering by reducing the thickness of magnetic films below the mean free path [3] can enhance the effect by orders of magnitude. Thin films of ordinary transition metals (Ni, Co, Fe) with dominant surface scattering were shown to reach EHE resistivity of the order of 1 µΩcm [1], whereas ultrathin alloys of FePt [4] and CoFe/Pt multilayers [5] reach the values of about 5 µΩcm.Tuning the perpendicular anisotropy in CoFe/Pt multilayers, and thus reducing the magnetic saturation field below the typical demagnetizing value, was shown to provide the field sensitivity exceeding 10 3 Ω/T [5] which competes with the best semiconducting Hall sensors. Use of the EHE for magnetic memory devices with a direct data read-out is another potential application. Combination of an out-of-plane anisotropy with a strong remanent EHE signal has been demonstrated in thin Ni films [1,6] at low temperatures.The goal of this work was the exploration of thin Co/Pd multilayers with room temperature perpendicular anisotropy in the thickness limit in which surface scattering can boost the magnitude of EHE, similar to the chemically homogeneous thin films. We shall demonstrate that the generation of room temperature magnetic memory units, and respectively, the magnetic random access memory based on the extraordinary Hall effect, is feasible. However, probably the most interesting and unexpected result we report on is the thickness and aging dependence of the EHE polarity in thin Co/Pd multilayers.

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“…From studies of RE-TM amorphous alloy films it is known that the sign of the Hall resistivity changes at the compensation composition due to the change in spin direction [25][26][27][28], meaning that either the Fe or Tb magnetic moment dominates in the perpendicular anisotropy. For Tb/Fe multilayers with different layer thickness it was also shown that the Hall voltage dependence is determined by the interface [29,30]. For Fe/Au/Tb trilayers the indirect exchange between Fe and Tb goes by means of polarized conduction electrons of Au.…”

Section: The Sign Change Of the Couplingmentioning

confidence: 99%

Oscillations and change of sign in indirect exchange coupling of Fe/Au/Tb trilayer structures

Shypil¹,

Pogorily²,

Podyalovsky³

2004

Low Temperature Physics

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Indirect exchange coupling between Fe and Tb layers through an Au layer showed oscillatory behavior with the thickness of the nonmagnetic metal. Different experimental tools such as polar magneto-optical Kerr effect, ferromagnetic resonance, and magnetotransport were used to investigate Fe/Au/Tb trilayers with Au thickness varying from 0 to 3.5 nm, prepared in an MBE system. From the experimental data we reconstruct the dynamics of the Fe and Tb magnetic moments with increasing thickness of the Au interlayer and show for the first time that there is a change of sign in the interaction between Fe and Tb, which is observed experimentally.

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Magnetic properties of Pd/Co multilayer films studied by Hall effect

Cited by 23 publications

References 10 publications

Temperature and Co thickness dependent sign change of the anomalous Hall effect in Co/Pd multilayers: An experimental and theoretical study

Temperature and Co thickness dependent sign change of the anomalous Hall effect in Co/Pd multilayers: An experimental and theoretical study

Reversal of the extraordinary Hall effect polarity in thin Co/Pd multilayers

Oscillations and change of sign in indirect exchange coupling of Fe/Au/Tb trilayer structures

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