Purely antiferromagnetic magnetoelectric random access memory

Kosub, Tobias; Kopte, Martin; Hühne, Ruben; Appel, Patrick; Shields, Brendan; Maletinsky, Patrick; Hübner, René; Liedke, Maciej Oskar; Faßbender, J.; Schmidt, Oliver G.; Makarov, Denys

doi:10.1038/ncomms13985

Cited by 247 publications

(258 citation statements)

References 46 publications

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“…Since the Néel vector and the surface magnetization in chromia can be electrically switched, this result indicates the possibility of the voltage controlled QAHE at low temperature. We note that a reversible AHE has been realized experimentally at room temperature, although using Pt rather than graphene, as an overlayer on chromia [40].…”

Section: Anomalous and Valley Hall Conductancementioning

confidence: 90%

Magnetoelectric control of topological phases in graphene

et al. 2019

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Topological antiferromagnetic (AFM) spintronics is an emerging field of research, which involves the topological electronic states coupled to the AFM order parameter known as the Néel vector. The control of these states is envisioned through manipulation of the Néel vector by spin-orbit torques driven by electric currents. Here we propose a different approach favorable for low-power AFM spintronics, where the control of the topological states in a two-dimensional material, such as graphene, is performed via the proximity effect by the voltage induced switching of the Néel vector in an adjacent magnetoelectric AFM insulator, such as chromia. Mediated by the symmetry protected boundary magnetization and the induced Rashba-type spin-orbit coupling at the interface between graphene and chromia, the emergent topological phases in graphene can be controlled by the Néel vector. Using density functional theory and tightbinding Hamiltonian approaches, we model a graphene/Cr2O3 (0001) interface and demonstrate non-trivial band gap openings in the graphene Dirac bands asymmetric between the K and K′ valleys. This gives rise to an unconventional quantum anomalous Hall effect (QAHE) with a quantized value of 2e 2 /h and an additional step-like feature at a value close to e 2 /2h, and the emergence of the spin-polarized valley Hall effect (VHE). Furthermore, depending on the Néel vector orientation, we predict the appearance and transformation of different topological phases in graphene across the 180° AFM domain wall, involving the QAHE, the valley-polarized QAHE and the quantum VHE (QVHE), and the emergence of the chiral edge state along the domain wall. These topological properties are controlled by voltage through magnetoelectric switching of the AFM insulator with no need for spin-orbit torques. A. Optimization of the graphene/Cr 2 O 3 (0001) interface structureThe in-plane position of graphene on the Cr2O3 (0001) surface was optimized by considering three different interface structures: (1) a graphene C atom is atop the Cr atom of the Cr2O3 surface (Figures 1a,b in the main text), (2) a graphene C atom is atop the O atom in the first O monolayer from the Cr2O3 surface ( Figure S1a), and (3) the Cr surface atom is below the center of a hexagonal ring of graphene ( Figure S1b). Starting from these initial configurations, the atomic structure of the whole supercell is relaxed. We find that the lowest total energy structure forms C located atop Cr (Figures 1a,b in the main text). The structure with C atop O atom ( Figure S1a) and the structure with Cr under the graphene hollow site, respectively, have the total energy 36 meV and 55 meV higher. In the main text, we focus on the most stable atomic structure to investigate the electric, magnetic, and spin transport of the on the Cr2O3 (0001) interface.

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Section: Anomalous and Valley Hall Conductancementioning

confidence: 90%

Magnetoelectric control of topological phases in graphene

et al. 2019

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“…Typical mechanisms involve direct coupling between ferroic orders, as in perovskite BiFeO 3 , where the ferroelectric and antiferromagnetic orders coexist (Sando, Barthélémy, and Bibes, 2014). A purely antiferromagnetic magnetoelectric random access memory was recently demonstrated using the magnetoelectric antiferromagnet Cr 2 O 3 (Kosub et al, 2017). Alternatively, the magnetoelectric effect in the antiferromagnet gives rise to electrically induced interface magnetization which can couple to an adjacent ferromagnetic film, such as with Cr 2 O 3 =½Co=Pd multilayers (He et al, 2010).…”

Section: Insulatorsmentioning

confidence: 99%

“…Direct observation usually requires large scale facilities with element-sensitive techniques like x-ray absorption spectroscopy (Weber et al, 2003;Salazar-Alvarez et al, 2009;Wu et al, 2011) or specific techniques with local probes like spin-polarized scanning tunneling microscopy (Bode et al, 2006;Loth et al, 2012) and quantum sensing with single spins (nitrogen vacancies) in diamond (Gross et al, 2017;Kosub et al, 2017). Alternatively, some information about antiferromagnetic domains can be inferred using indirect transport measurements.…”

Section: A Experimental Observation Of Antiferromagnetic Texturesmentioning

confidence: 99%

Antiferromagnetic spintronics

et al. 2018

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Antiferromagnetic materials could represent the future of spintronic applications thanks to the numerous interesting features they combine: they are robust against perturbation due to magnetic fields, produce no stray fields, display ultrafast dynamics, and are capable of generating large magnetotransport effects. Intense research efforts over the past decade have been invested in unraveling spin transport properties in antiferromagnetic materials. Whether spin transport can be used to drive the antiferromagnetic order and how subsequent variations can be detected are some of the thrilling challenges currently being addressed. Antiferromagnetic spintronics started out with studies on spin transfer and has undergone a definite revival in the last few years with the publication of pioneering articles on the use of spin-orbit interactions in antiferromagnets. This paradigm shift offers possibilities for radically new concepts for spin manipulation in electronics. Central to these endeavors are the need for predictive models, relevant disruptive materials, and new experimental designs. This paper reviews the most prominent spintronic effects described based on theoretical and experimental analysis of antiferromagnetic materials. It also details some of the remaining bottlenecks and suggests possible avenues for future research. This review covers both spin-transfer-related effects, such as spin-transfer torque, spin penetration length, domain-wall motion, and "magnetization" dynamics, and spin-orbit related phenomena, such as (tunnel) anisotropic magnetoresistance, spin Hall, and inverse spin galvanic effects. Effects related to spin caloritronics, such as the spin Seebeck effect, are linked to the transport of magnons in antiferromagnets. The propagation of spin waves and spin superfluids in antiferromagnets is also covered.

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“…Very recently, NV microscopy imaged nanoscale ferrimagnetic domains in antiferromagnetic random access memories [133]. We underline that part of these measurements were performed in zero field cooling (ZFC), taking advantage of low-invasive sensing using NV centers.…”

Section: Recent Applications Of Single Nv Sensingmentioning

confidence: 99%

Nanoscale Sensing Using Point Defects in Single-Crystal Diamond: Recent Progress on Nitrogen Vacancy Center-Based Sensors

et al. 2017

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Individual, luminescent point defects in solids, so-called color centers, are atomic-sized quantum systems enabling sensing and imaging with nanoscale spatial resolution. In this overview, we introduce nanoscale sensing based on individual nitrogen vacancy (NV) centers in diamond. We discuss two central challenges of the field: first, the creation of highly-coherent, shallow NV centers less than 10 nm below the surface of a single-crystal diamond; second, the fabrication of tip-like photonic nanostructures that enable efficient fluorescence collection and can be used for scanning probe imaging based on color centers with nanoscale resolution.

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Purely antiferromagnetic magnetoelectric random access memory

Cited by 247 publications

References 46 publications

Magnetoelectric control of topological phases in graphene

Magnetoelectric control of topological phases in graphene

Antiferromagnetic spintronics

Nanoscale Sensing Using Point Defects in Single-Crystal Diamond: Recent Progress on Nitrogen Vacancy Center-Based Sensors

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