Predictions for the formation of atomic chains in mechanically controllable break-junction experiments

Fernández-Seivane, Lucas; García‐Suárez, Víctor M.; Ferrer, Jaime

doi:10.1103/physrevb.75.075415

Cited by 35 publications

(62 citation statements)

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“…[13]. This implementation has been tested satisfactorily in several bulk semiconductors and metals [13], some molecular magnets [14], a large number of atomic chains [15] and a good number of small metallic (in the present work) and intermetallic clusters [14] by now. We have crosschecked our results for Ir 2 and Pt 2,3 with the plane-wave, Vanderbilt pseudopotentials code Quantum ESPRESSO [16].…”

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confidence: 79%

Magnetic Anisotropies of Late Transition Metal Atomic Clusters

Fernández-Seivane

Ferrer

2007

Phys. Rev. Lett.

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We analyze the impact of the magnetic anisotropy on the geometric structure and magnetic ordering of small atomic clusters of palladium, iridium, platinum and gold, using Density Functional Theory. Our results highlight the absolute need to include self-consistently the spin orbit interaction in any simulation of the magnetic properties of small atomic clusters, and a complete lack of universality in the magnetic anisotropy of small-sized atomic clusters. PACS numbers: 36.40.Cg, 71,70.Ej, 75.30.Gw Nanostructures of all kinds display a wealth of fascinating geometric, mechanical, electronic, magnetic or optical properties. The exploding field of Nanoscience pretends to understand, handle and tailor these properties for human benefit. Atomic clusters and chains, molecular magnets, and a number of organic molecules like for instance metallocenes indeed show novel magnetic behaviors, that include the enhancement of magnetic moments due to the reduced coordination and symmetry of the geometry [1], and a rich variety of new non-collinear magnetic structures that are absent in bulk materials [2]. Among all these devices, metallic atomic clusters (MACs) [3] stand out since, on the one hand they represent the natural bridge between atomic and materials physics and, in the other, they can be grown, deposited on surfaces or embedded in diverse matrices, and characterized with relatively well-established techniques. Further, the magnetic properties of MACs show promise for a wide spectrum of applications, ranging from medicine to spintronics.Magnetism in small MACs has been extensively studied both experimentally and theoretically along the past decade [4,5]. It is therefore somewhat surprising that, even though spin-orbit effects are also expected to be enhanced in MACs, there are very few published theoretical papers that include the spin-orbit interaction (SOI) in their simulations [6,7,8,9]. Among these, only a handful have actually looked at the explicit effects of the SOI on the magnetism of MAC. Pastor and coworkers have studied the magnetic anisotropy (MA) [10] of clusters of 3d Transition Metal atoms, using a phenomenological tightbinding scheme. To the best of our knowledge, there are no ab initio studies of the impact of the SOI on the magnetism of 4d and 5d MAC. This includes not only explicit calculations of the magnetic anisotropy energy (MAE), but also and more importantly, whether the SOI modifies the ground state and the tower of lowest lying (magnetic) states of a given cluster.We present in this article a series of calculations of selected atomic clusters of 4d-and specially 5d-elements, that show that the SOI is a key ingredient in any ab initio simulation of heavy transition metal MAC, that should not be overlooked. These include Pd n , Ir n , Pt n and Au n , with n=2, 3, 4 and 5, and also Pd 6 and Au 6 , Au 7 . The rationale behind our choice is that 5d MAC are expected to have the largest MAEs; among all 5d elements, gold is monovalent and should display a simpler behavior; comparing the magnetic p...

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confidence: 79%

Magnetic Anisotropies of Late Transition Metal Atomic Clusters

Fernández-Seivane

Ferrer

2007

Phys. Rev. Lett.

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“…It is, therefore, of interest to investigate possible ferromagnetic (FM) and antiferromagnetic (AF) magnetization in the linear chains of all 4d and 5d transition metals including Y, Zr, Nb, La, Hf and Ta zigzag chain which appear not to have been considered. As mentioned before, recent ab initio calculations indicate that the zigzag chain structure of, at least, Zr 23 , Ir 16 , Pt 16 and Au 16,25 , is energetically more favorable than the linear chain structure. Thus, we also study the structural, electronic and magnetic properties of all 4d and 5d transition metal zigzag chains in order to understand how the physical properties of the monoatomic chains evolve as their structures change from the linear to zigzag chain.…”

Section: Introductionmentioning

confidence: 72%

“…16. Surprisingly, the second energy minimum state in the Nb, Mo, Tc, W and Re chains (Table V) is in fact the global energy minimum, i.e., its total energy is below the corresponding minimum energy listed in Table IV.…”

Section: The Zrmentioning

confidence: 88%

“…16,55 To systematically study these possible elongated zigzag structures, we therefore further calculated the total energy as a function of the fixed lattice constant d 1 with d 1 varying from 2.0Å to 6.0Å for all the 4d and 5d zigzag chains. The structural parameters for the second local (or global) energy minimum state of the zigzag chains are listed in Table V.…”

Section: The Zrmentioning

confidence: 99%

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Magnetic moment and magnetic anisotropy of linear and zigzag4dand5dtransition metal nanowires: First-principles calculations

Tung

Guo

2010

Phys. Rev. B

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An extensive ab initio study of the physical properties of both linear and zigzag atomic chains of all 4d and 5d transition metals (TM) within the generalized gradient approximation by using the accurate projector-augmented wave method, has been carried out. The atomic structures of equilibrium and metastable states were theoretically determined. All the TM linear chains are found to be unstable against the corresponding zigzag structures. All the TM chains, except Nb, Ag and La, have a stable (or metastable) magnetic state in either the linear or zigzag or both structures. Magnetic states appear also in the sufficiently stretched Nb and La linear chains and in the largely compressed Y and La chains. The spin magnetic moments in the Mo, Tc, Ru, Rh, W, Re chains could be large (≥1.0 µB/atom). Structural transformation from the linear to zigzag chains could suppress the magnetism already in the linear chain, induce the magnetism in the zigzag structure, and also cause a change of the magnetic state (ferromagnetic to antiferroamgetic or vice verse). The calculations including the spin-orbit coupling reveal that the orbital moments in the Zr, Tc, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir and Pt chains could be rather large (≥0.1 µB/atom). Importantly, large magnetic anisotropy energy (≥1.0 meV/atom) is found in most of the magnetic TM chains, suggesting that these nanowires could have fascinating applications in ultrahigh density magnetic memories and hard disks. In particular, giant magnetic anisotropy energy (≥10.0 meV/atom) could appear in the Ru, Re, Rh, and Ir chains. Furthermore, the magnetic anisotropy energy in several elongated linear chains could be as large as 40.0 meV/atom. A spin-reorientation transition occurs in the Ru, Ir, Ta, Zr, La and Zr, Ru, La, Ta and Ir linear chains when they are elongated. Remarkably, all the 5d as well as Tc and Pd chains show the colossal magnetic anisotropy (i.e., it is impossible to rotate magnetization into certain directions). Finally, the electronic band structure and density of states of the nanowires have also been calculated in order to understand the electronic origin of the large magnetic anisotropy and orbital magnetic moment as well as to estimate the conduction electron spin polarization.

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“…Nanoparticles of Pt are often used as a catalyst, for instance in catalytic converters in automobiles and in fuel cells, where the size of these nanoparticles is an important parameter [69]. A more recent development in the research of Pt has been the discovery that it is one of three metals found to form monoatomic chains, along with Au and Ir [1,[70][71][72][73]. During the last decade, theoretical investigations on such atomic-sized Pt contacts have predicted the emergence of magnetism in such small structures [74][75][76].…”

Section: Potential Magnetism In Atomic-sized Pt Contactsmentioning

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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Predictions for the formation of atomic chains in mechanically controllable break-junction experiments

Cited by 35 publications

References 32 publications

Magnetic Anisotropies of Late Transition Metal Atomic Clusters

Magnetic Anisotropies of Late Transition Metal Atomic Clusters

Magnetic moment and magnetic anisotropy of linear and zigzag4dand5dtransition metal nanowires: First-principles calculations

Electron Transport in Magnetic Quantum Point Contacts

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