Magnetoresistance of atomic-size contacts realized with mechanically controllable break junctions

Egle, Stefan; Bacca, Cecile; Pernau, Hans‐Fridtjof; Huefner, Magdalena; Hinzke, Denise; Nowak, Ulrich; Scheer, Elke

doi:10.1103/physrevb.81.134402

Cited by 60 publications

(61 citation statements)

References 37 publications

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“…Large variations of MR curves including sign changes of the GMR are typical observations in atomic contacts [36][37][38] in qualitative agreement with calculations of the geometry dependence of the spin polarization, which becomes important at the atomic level. [39][40][41][42] It has been shown that the magnetic properties of all relevant length and size scales of a sample are reflected in the MR traces.…”

Section: Resultssupporting

confidence: 68%

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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Section: Resultssupporting

confidence: 68%

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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“…This technique has been successfully used both in magnetic and superconducting point contacts for spintronics and quantum computing studies. [20][21][22] In the case of Pt, it is predicted that as the number of atoms in the chain or the interatomic distance is increased, so is the magnetic moment. 1, 3 The actual conductance of a Pt atomic wire will depend on the exact orbital overlap, i.e.…”

mentioning

confidence: 99%

Unexpected Magnetic Properties of Gas-Stabilized Platinum Nanostructures in the Tunneling Regime

et al. 2014

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International audienceNanostructured materials often have properties widely different from bulk, imposed by quantum limits to a physical property of the material. This includes, for example, superparamagnetism and quantized conductance, but original properties such as magnetoresistance in nonmagnetic molecular structures may also emerge. In this Letter, we report on the atomic manipulation of platinum nanocontacts in order to induce magnetoresistance. Platinum is a paramagnetic 5d metal, but atomic chains of this material have been predicted to be magnetically ordered with a large anisotropy. Remarkably, we find that a gas flow stabilizes Pt atomic structures in a break junction experiment, where we observe extraordinary resistance changes over 30 000% in a temperature range up to 77 K. Simulations indicate that this behavior may stem from a previously unknown magnetically ordered, low-energy state in platinum oxide atomic chains. This is supported by measurements in Pt/ PtOx superlattices revealing the presence of a ferromagnetic moment. These properties open new paths of research for atomic scale " dirty " magnetic sensors and quantum devices

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“…Moreover, since the conductance also depends on the electrode displacement, one could argue that magnetoresistive effects may be an additional factor. However, we found that such effect are not strong enough to explain the high MRR observed in the atomic contact regime, while they may be more significant in tunnelling regime [68]. The vacuum tunnelling current depends exponentially on the electrode separation.…”

Section: Ferromagnetic (Co) Single-atom Contactsmentioning

confidence: 40%

“…Hence, for systems smaller than this length scale, the orbital momenta of the conduction electrons are not quenched and may play an important role for the MR. If the size of the external magnetic field is sufficiently large, it aligns the orbitals and thus directly affects the superposition of the wave functions and hence the conduction channels and their transmissions [55,68]. If this mechanism is the reason for the observed MR, also the effects known from homogeneous systems, such as the AMR, should gradually be enhanced upon decreasing the size of the contacts.…”

Section: Heterocontacts Based On Au and Comentioning

confidence: 99%

Electron Transport in Magnetic Quantum Point Contacts

et al. 2012

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In recent years, the fabrication of novel building blocks for quantum computation-and spintronics devices gained significant attention. The ultimate goal in terms of miniaturization is the creation of single-atom functional elements. Practically, quantum point contacts are frequently used as model systems to study the fundamental electronic transport properties of such mesoscopic systems. A quantum point contact is characterised by a narrow constriction coupling two larger electron reservoirs. In the absence of a magnetic field, the conductance of these quantum point contacts is quantised in multiples of 2e 2 /h, the so-called conductance quantum (G 0 ). However, in the presence of magnetic fields the increased spin-degeneracy often gives rise to a deviation from the idealized behaviour and therefore leads to a change in the characteristic conductance of the quantum point contact. Herein, we illustrate the complex magnetotransport characteristics in quantum point contacts and magnetic heterojunctions. The theoretical framework and experimental concepts are discussed briefly together with the experimental results as well as potential applications.

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Magnetoresistance of atomic-size contacts realized with mechanically controllable break junctions

Cited by 60 publications

References 37 publications

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

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

Unexpected Magnetic Properties of Gas-Stabilized Platinum Nanostructures in the Tunneling Regime

Electron Transport in Magnetic Quantum Point Contacts

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