Morphology of Monolayer MgO Films on Ag(100): Switching from Corrugated Islands to Extended Flat Terraces

Pal, Jagriti; Smerieri, Marco; Celasco, Edvige; Savio, Letizia; Vattuone, L.; Rocca, M.

doi:10.1103/physrevlett.112.126102

Cited by 61 publications

(90 citation statements)

References 38 publications

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“…To grow MgO, we exposed an atomically clean Ag(100) single crystal, held at ~600 K, to an Mg flux from a Knudsen cell in an oxygen partial pressure of ~10 −6 mbar up to a MgO coverage of 1.5 monolayers. The growth rate was ~0.5 monolayers per minute 30,31 . We assumed in-plane commensurability between the Ag and MgO lattices and a low-temperature Ag lattice parameter of 408.67 pm 28 .…”

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confidence: 99%

Reading and writing single-atom magnets

Natterer

Yang

Paul

et al. 2017

Nature

353

362

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The highest-density magnetic storage media will code data in single-atom bits. To date, the smallest individually addressable bistable magnetic bits on surfaces consist of 5-12 atoms 1,2 . Long magnetic relaxation times were demonstrated in molecular magnets containing one lanthanide atom [3][4][5][6][7][8][9][10][11] , and recently in ensembles of single holmium (Ho) atoms supported on magnesium oxide (MgO) 12 . Those experiments indicated the possibility for data storage at the fundamental limit, but it remained unclear how to access the individual magnetic centers. Here we demonstrate the reading and writing of individual Ho atoms on MgO, and show that they independently retain their magnetic information over many hours. We read the Ho states by tunnel magnetoresistance 13,14 and write with current pulses using a scanning tunneling microscope. The magnetic origin of the long-lived states is confirmed by single-atom electron paramagnetic resonance (EPR) 15 on a nearby Fe sensor atom, which shows that Ho has a large out-of-plane moment of (10.1 ± 0.1) µB on this surface. In order to demonstrate independent reading and writing, we built an atomic scale structure with two Ho bits to which we write the four possible states and which we read out remotely by EPR. The high magnetic stability combined with electrical reading and writing shows that single-atom magnetic memory is possible. 2The demonstration of magnetic bistability in single molecule magnets containing one rare earth atom 3,5,8,10 illustrated the potential of single-atom spin centers in future storage media 4,6,7,9,11 . A ligand field that provides a barrier against magnetization reversal by lifting the Hund degeneracies in single molecule magnets 3-10 can also be realized for atoms bound to a surface [16][17][18][19] . While a break junction probes the quantum states of one isolated molecule 20 , a surface enables preparation of and access to numerous spin centers. Magnetic lifetimes in the milliseconds range were accordingly obtained for single 3d atoms on magnesium oxide (MgO) 21 but the report of magnetic bistability for Ho atoms on a platinum surface is debated [22][23][24][25] . A major advance of observing magnetic remanence was recently achieved with an ensemble of isolated Ho atoms on MgO 12 , yet the question remained whether electrical probing of the highly localized f orbitals of individual rare earth atoms is possible 23,26,27 .Here we address the magnetic switching of individual Ho atoms on MgO, which we control by current pulses and detect by changes to the tunnel magnetoresistance using a spinpolarized scanning tunneling microscope (STM) 13 . We prove the magnetic origin of the switching in the tunneling resistance by STM-enabled single-atom electron paramagnetic resonance (EPR) on an adjacent iron (Fe) sensor atom. Additionally, we determine by this method the out-of-plane component of the Ho magnetic moment, and use the long lifetime to store two bits of information in an array of two Ho atoms whose magnetic state can be read remotely ...

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confidence: 99%

Reading and writing single-atom magnets

Natterer

Yang

Paul

et al. 2017

Nature

353

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“…On the irregular steps, a large fraction of kink sites is seen. Recently, the possibility of controlling the shape and size, and thus the defectivity of MgO islands on Ag(001) by variation of the growth conditions has been demonstrated [54].…”

Section: Mgo Model Surfacesmentioning

confidence: 99%

Atomic Scale Characterization of Defects on Oxide Surfaces

Nilius

Sterrer

Heyde

et al. 2015

Springer Series in Surface Sciences

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The physics and chemistry of oxide surfaces cannot be recognized without taking into account the variety of lattice defects. Defects largely govern the electronic and optical properties of oxides, they offer potential binding sites for atoms and molecules, and serve as charge centers that control the donor or acceptor character of the material. In this contribution, we demonstrate how the nature of surface defects on oxides can be probed in an ensemble but also on the level of individual defects, focusing on defects on the surface of thin, single-crystalline oxide films of MgO and CeO₂ as prototype examples for non-reducible and reducible oxides, respectively. Scanning probe techniques play a fundamental role in this respect, as they enable direct visualization of surface defects and provide insight into the electronic structure of defects and local potential modulations in their vicinity

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“…Design and fabrication of nanoclusters is a new inspiring field because of their amazing features that are remarkably different from classical materials [1][2][3][4]. The beneficial electronic, optical, magnetic, and chemical properties of nanoclusters can be employed in many fields, such as optoelectronic devices [5,6], single-electronic devices [7], ultrahigh-density magnetic recording [8][9][10], and quantum computing.…”

Section: Introductionmentioning

confidence: 99%

Novel Evolution Process of Zn-Induced Nanoclusters on Si(111)-(7×7) Surface

Zhou

Chen

et al. 2015

Nano-Micro Lett.

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A tiny number of Zn atoms were deposited on Si (111)- (797) surface to study the evolution process of Zninduced nanoclusters. After the deposition, three types (type I, II, and III) of Zn-induced nanoclusters were observed to occupy preferably in the faulted half-unit cells. These Zn-induced nanoclusters are found to be related to one, two, and three displaced Si edge adatoms, and simultaneously cause the depression of one, two, and three closest Si edge adatoms in the neighboring unfaulted half-unit cells at negative voltages, respectively. First-principles adsorption energy calculations show that the observed type I, II, and III nanoclusters can reasonably be assigned as the Zn 3 Si 1 , Zn 5 Si 2 , and Zn 7 Si 3 clusters, respectively. And Zn 3 Si 1 , Zn 5 Si 2 , and Zn 7 Si 3 clusters are, respectively, the most stable structures in cases of one, two, and three displaced Si edge adatoms. Based on the above energy-preferred models, the simulated bias-dependent STM images are all well consistent with the experimental observations. Therefore, the most stable Zn 7 Si 3 nanoclusters adsorbed on the Si(111)-(797) surface should grow up on the base of Zn 3 Si 1 and Zn 5 Si 2 clusters. A novel evolution process from Zn 3 Si 1 to Zn 5 Si 2 , and finally to Zn 7 Si 3 nanocluster is unveiled.

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Morphology of Monolayer MgO Films on Ag(100): Switching from Corrugated Islands to Extended Flat Terraces

Cited by 61 publications

References 38 publications

Reading and writing single-atom magnets

Reading and writing single-atom magnets

Atomic Scale Characterization of Defects on Oxide Surfaces

Novel Evolution Process of Zn-Induced Nanoclusters on Si(111)-(7×7) Surface

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