Oscillations with Co and Cu thickness of the current-perpendicular-to-plane giant magnetoresistance of a Co/Cu/Co(001) trilayer

Mathon, J.; Umerski, A.; Villeret, Murielle

doi:10.1103/physrevb.55.14378

Cited by 56 publications

(56 citation statements)

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“…It is interesting to observe that the angular dependence of the GMR for CIP seems to be governed mostly by the first term in the expansion, whereas -depending on the regime -in the case of the IEC the second term can indeed be important. For CPP, it has been proposed that in the asymptotic regime, i.e., when the number of spacer layers becomes very large, the oscillatory behavior of the IEC and CPP-MR with respect to the spacer thickness are closely related to the Fermi surface of the spacer material [6].…”

Section: Resultsmentioning

confidence: 99%

“…In addition, we have previously used the same SKKR method to calculate the interlayer exchange coupling (IEC) of multilayered structures, and it is of interest to compare the angular dependence of the GMR and IEC. There have been suggestions that the two are related for the CPP geometry [6], but for CIP there is no reason for similar orientational dependencies for the GMR and the IEC.…”

Section: Introductionmentioning

confidence: 99%

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On the orientational dependence of giant magnetoresistance

et al. 1999

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Abstract. The functional dependence of the giant magnetoresistance (GMR) with respect to the relative angle between the orientations of the magnetization in the magnetic slabs of a trilayer system is calculated by using the Kubo-Greenwood formula for electrical transport together with the fully-relativistic spinpolarized screened Korringa-Kohn-Rostoker method for semi-infinite systems and the coherent potential approximation. It is found that the functional dependence of the GMR is essentially of the form (1−cos ϕ). PACS

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the orientational dependence of giant magnetoresistance

et al. 1999

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“…From the theoretical point of view this is confusing, since in addition to the Fermi wave vector [21], another wave vector, i.e., the cutoff k-point k cp , given by the depth of the quantum well, is also known to contribute to the conductance oscillations [22]. This wave vector dominates the predicted oscillations of CPP-GMR in a Co/Cu/Co trilayer [23]. In fact, the calculated oscillations of TMR for a clean junction [17] cannot be explained by a single period determined by k F only.…”

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confidence: 99%

Quantum oscillation of magnetoresistance in tunneling junctions with a nonmagnetic spacer

et al. 2003

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We make a theoretical study of the quantum oscillations of the tunneling magnetoresistance (TMR) as a function of the spacer layer thickness. Such oscillations were recently observed in tunneling junctions with a nonmagnetic metallic spacer at the barrier-electrode interface. It is shown that momentum selection due to the insulating barrier and conduction via quantum well states in the spacer, mediated by diffusive scattering caused by disorder, are essential features required to explain the observed period of oscillation in the TMR ratio and its asymptotic value for thick nonmagnetic spacer.PACS numbers: 75.70.Pa, 73.40.Gk Large magnetoresistance [1,2] observed in ferromagnetic tunneling junctions such as Fe/Al 2 O 3 /Fe and Co/Al 2 O 3 /CoFe currently attracts much interest due to the possibility of its application to magnetic sensors and MRAM elements. Because the tunneling magnetoresistance (TMR) ratio is related to the spin polarization of the ferromagnetic leads [3,4], attempts have been made to fabricate junctions with more highly spin-polarized ferromagnets [5,6]. Realistic calculations [7,8], on the other hand, have given much higher TMR ratios than the observed values, which is probably due to their assumption of epitaxial structures. Recent experiments on TMR using epitaxial junctions [9,10,11], however, were unsuccessful in producing TMR ratios as high as expected. Thus, our understanding of the relationship between the electronic structure of the ferromagnets and the TMR ratio is far from complete.The most important factor governing the TMR ratio may be the electronic structure at junction interfaces [12,13]. In order to clarify its role, several experiments have been performed to measure the dependence of TMR ratio on the thickness of a nonmagnetic metal layer inserted at the interface [14,15,16]. The observed TMR ratios show almost monotonic decrease with increasing thicknesses of inserted layers of Au, Cu, or Cr, contrary to a theoretical study for clean junctions [17] which shows clear oscillations of the TMR ratio as a function of the nonmagnetic layer thickness. Zhang and Levy [18] have successfully explained this decrease in TMR ratio in terms of the decoherence of electron propagation across a nonmagnetic layer. However, recent experiments by Yuasa et al. show clear oscillations of the TMR ratio as a function of Cu layer thickness for high quality NiFe/Al 2 O 3 /Cu/Co junctions in which the Co/Cu electrode is a single crystal [19]. In their experiments, two characteristic features of the oscillations have been observed: (i) the average TMR ratio decays to zero with increasing nonmagnetic layer thickness; (ii) the period of the oscillations is determined solely by the belly or long period Fermi wave vector k F of Cu. The observed period agrees quite well with that of the oscillations of photoemission spectra caused by quantum well states in Co/Cu multilayers [20]. From the theoretical point of view this is confusing, since in addition to the Fermi wave vector [21], another wave vector, i....

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“…Transport calculations require a knowledge of the underlying electronic structure. Semi-empirical tightbinding models of electronic structure have been used successfully in modeling SDT in thin film structures involving Fe and other magnetic metals together with insulating or vacuum tunnel barriers or non-magnetic metal spacers, 28,29,30,31,32 and also SDT in magnetic metal nanocontacts. 16 They have also been used successfully to explain the experimental current-voltage characteristics of molecular nanowires connecting non-magnetic metal electrodes.…”

Section: (2)mentioning

confidence: 99%

Theoretical study of spin-dependent electron transport in atomic Fe nanocontacts

Dalgleish

Kirczenow

2005

Phys. Rev. B

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We present theoretical predictions of spintronic transport phenomena that should be observable in ferromagnetic Fe nanocontacts bridged by chains of Fe atoms. We develop appropriate model Hamiltonians based on semi-empirical considerations and the known electronic structure of bulk Fe derived from ab initio density functional calculations. Our model is shown to provide a satisfactory description of the surface properties of Fe nano-clusters as well as bulk properties. LippmannSchwinger and Green's function techniques are used together with Landauer theory to predict the current, magneto-resistance, and spin polarization of the current in Fe nanocontacts bridged by atomic chains under applied bias. Unusual device characteristics are predicted including negative magneto-resistance and spin polarization of the current, as well as spin polarization of the current for anti-parallel magnetization of the Fe nanocontacts under moderate applied bias. We explore the effects that stretching the atomic chain has on the magneto-resistance and spin polarization and predict a cross-over regime in which the spin polarization of the current for parallel magnetization of the contacts switches from negative to positive. We find resonant transmission due to dangling bond formation on tip atoms as the chain is stretched through its breaking point to play an important role in spin-dependent transport in this regime. The physical mechanisms underlying the predicted phenomena are discussed.PACS numbers: 75.47.-m,73.63.-b,72.25.-b,72.10.-d

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Oscillations with Co and Cu thickness of the current-perpendicular-to-plane giant magnetoresistance of a Co/Cu/Co(001) trilayer

Cited by 56 publications

References 23 publications

On the orientational dependence of giant magnetoresistance

On the orientational dependence of giant magnetoresistance

Quantum oscillation of magnetoresistance in tunneling junctions with a nonmagnetic spacer

Theoretical study of spin-dependent electron transport in atomic Fe nanocontacts

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