Weak localization and electron-electron interaction in percolating nickel films

Aprili, M.; Lesueur, J.; Dumoulin, L.; Nédellec, P.

doi:10.1016/s0038-1098(96)00779-x

Cited by 40 publications

(32 citation statements)

References 22 publications

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“…Nevertheless, weak localization corrections were observed, e.g., in Ni films. 15 We can present some numerical estimations of the magnitude of B int . For example, in the case of Fe we take 39 4πM 0 ≃ 2 T. Thus, for the bulk Fe, when the demagnetizing field is negligibly small, we have B int ≃ 2 T. The critical magnetic induction B crit , which can totally suppress the localizations correction, is determined differently in 3D and 2D cases.…”

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confidence: 99%

Weak localization in ferromagnets with spin-orbit interaction

2001

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Weak localization corrections to conductivity of ferromagnetic systems are studied theoretically in the case when spin-orbit interaction plays a significant role. Two cases are analyzed in detail: (i) the case when the spin-orbit interaction is due to scattering from impurities, and (ii) the case when the spin-orbit interaction results from reduced dimensionality of the system and is of the Bychkov-Rashba type. Results of the analysis show that the localization corrections to conductivity of ferromagnetic metals lead to a negative magnetoresistance -also in the presence of the spin-orbit scattering. Positive magnetoresistance due to weak antilocalization, typical of nonmagnetic systems, does not occur in ferromagnetic systems. In the case of two-dimensional ferromagnets, the quantum corrections depend on the magnetization orientation with respect to the plane of the system.

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confidence: 99%

Weak localization in ferromagnets with spin-orbit interaction

2001

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“…The main issue is related to an internal magnetic field which may suppress the localization corrections. However, nonvanishing localization corrections were observed, e.g., in percolating Ni films [10]. On the other hand, the available results on low-temperature transport properties of epitaxial iron films [9] can be explained by both localization and interaction corrections.…”

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confidence: 99%

Electron-electron interaction effects in magnetic layered structures

Dugaev

Barnaś

2001

Europhys. Lett.

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Abstract. -We consider some peculiarities of the logarithmic electron-electron interaction corrections to conductivity, which can arise in magnetic quantum wells due to spin-splitting of energy levels. The matrix elements of Coulomb interaction include different screening contributions from spin-up and spin-down electrons, which can lead to anomalous behavior of the interaction constant when the width of a spin quantum well is changed. Our results explain qualitatively the physical origin of the recently observed anomalous behavior of the logarithmic term in electrical resistivity of Co/Cr/Ag/Co layered structures (Aliev F. G. et al., Phys. Rev. Lett., 78 (1997) 134).There has been a great interest recently in confined structures with magnetic and nonmagnetic materials, like metallic magnetic multilayers or magnetic tunnel junctions [1][2][3][4]. An important feature of such systems is the existence of spin quantum wells (SQWs), i.e., different quantum wells for electrons with opposite spin orientations. Although a lot of work has been done on transport properties of magnetic layered structures, the low-temperature regime, where quantum corrections due to weak localization and electron-electron interaction are important [5][6][7], is still not well understood [1,[8][9][10]. The main issue is related to an internal magnetic field which may suppress the localization corrections. However, nonvanishing localization corrections were observed, e.g., in percolating Ni films [10]. On the other hand, the available results on low-temperature transport properties of epitaxial iron films [9] can be explained by both localization and interaction corrections. As is well known, the electronelectron interaction corrections are weakly sensitive to magnetic field and therefore can be expected to play a significant role in magnetic materials [11].( * ) Present address:

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“…spin waves), and the interplay of FM order with coherence. These corrections have been discussed while considering [20] domain walls effects on conduction in FM nanowires/21], and magnetoresistive effectsl221 in thin FM films [23].…”

Section: Coherence In Ferromagnetsmentioning

confidence: 99%

Final Report: Novel Nanowires as Probes of Electron Coherence and Correlations in Restricted Geometries

Natelson¹

2005

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This is a final summary report of the research conducted under DEFG03-01ER4594G, which was a research program using metal nanostructures to examine quantum coherence of electrons in normal and ferromagnetic metals. This program was the PI'S first federal research grant, and by augmenting with other funds (Packard Foundation), this grant supported two graduate students during its duration. In normal metal nanostructures, quantum coherence was assessed by two independent techniques: weak localization magnetoresistance, and time-dependent universal conductance fluctuations (TDUCF noise). This work found that, in AuPd nanowires, the coherence information inferred from these two techniques were quantitatively consistent, even in the presence of magnetic impurity and phonon scattering. This confirmed theoretical expectations. However, in Ag and Au wires, the two techniques disagree, with noise measurements indicating a lower coherence length at low temperatures than weak localiztion. We have a candidate explanation for this, and are finishing these experiments. This work shows that subtleties remain in our understanding of coherence processes even in normal metals, particularly those involving the tunneling two-level systems that produce low frequency noise; this has relevance for quantum information processing implementations using metal devices. We have also studied time-dependent universal conductance fluctuations in ferromagnetic metals for the first time. The TDUCF in ferromagnetic nanowires show that the Cooperon channel of coherent processes is suppressed in these correlated materials. Furthermore, the surprisingly steep temperature dependence of the noise suggests that decoherence in these systems is through a different process than in normal metals. We are finishing nieasurements of "magnetofingerprint" conductance fluctuations in ferromagnetic metals to examine this unusual temperature dependence with an independent technique. This program has produced three papers (one Phys. Rev. B Rapid Communication, one PRB Brief Report, and a longer PRB article), with two more in preparation; it 1 1 s also resulted in six APS contributed talks by students, and two invited seminars by the PI. Over the last twenty years, tremendous progress has been made in understanding the role of quantum coherence in the dynamics of electrons in solids. Because the experimental consequences of quantum coherence are most readily detected in mesoscale systems, this discipline has come to be known as 'Lmesoscopics". The improved understanding of the role of quantum coherence in solid state systems has been driven by the development and widespread availability of sophisticated patterning and fabrication techniques with submicron resolution.Here I summarize the results of our research efforts using state-of-the-art nanostructures as tools to address fundamental, unresolved issues related to quantum coherence of electrons in conducting systems. The background and common methods of probing coherence physics are explained below in Sect...

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Weak localization and electron-electron interaction in percolating nickel films

Cited by 40 publications

References 22 publications

Weak localization in ferromagnets with spin-orbit interaction

Weak localization in ferromagnets with spin-orbit interaction

Electron-electron interaction effects in magnetic layered structures

Final Report: Novel Nanowires as Probes of Electron Coherence and Correlations in Restricted Geometries

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