Magnetic proximity effect at the three-dimensional topological insulator/magnetic insulator interface

Eremeev, S. V.; Men’shov, V. N.; Тугушев, В. В.; Echenique, Pedro M.; Chulkov, Eugene V.

doi:10.1103/physrevb.88.144430

Cited by 165 publications

(131 citation statements)

References 40 publications

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“…This overcomes the major disadvantage in MI-TI heterostructures where the proximity effect is considered weak [23]. To our knowledge, this is also the first report uniting TM doping and proximity effect in a MI.…”

Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 74%

“…However, due to the inplane anisotropy and low Curie temperature, such MIs are usually too weak to induce strong proximity magnetism in a TI. In fact, compared to a magnetically doped TI which can induce as large as a 50 meV surface band gap [4], the EuS-TI system has only a 7 meV gap opening due to the strongly localized Eu f orbitals [23]. Therefore, the enhancement of proximity magnetism is highly desirable to make it a valuable approach as doping hence takes full advantage.…”

mentioning

confidence: 99%

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Proximity-Driven Enhanced Magnetic Order at Ferromagnetic-Insulator–Magnetic-Topological-Insulator Interface

Chang

Kirby

et al. 2015

Phys. Rev. Lett.

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Magnetic exchange driven proximity effect at a magnetic-insulator-topological-insulator (MI-TI) interface provides a rich playground for novel phenomena as well as a way to realize low energy dissipation quantum devices. Here we report a dramatic enhancement of proximity exchange coupling in the MI/magnetic-TI EuS=Sb 2−x V x Te 3 hybrid heterostructure, where V doping is used to drive the TI (Sb 2 Te 3 ) magnetic. We observe an artificial antiferromagneticlike structure near the MI-TI interface, which may account for the enhanced proximity coupling. The interplay between the proximity effect and doping in a hybrid heterostructure provides insights into the engineering of magnetic ordering. The time-reversal symmetry (TRS) breaking and surface band gap opening of a topological insulator (TI) are essential ingredients necessary for towards the observation of novel quantum phases and realization for TI-based devices [1,2]. In general, there are two approaches to break the TRS: transitional-metal (TM) ion doping [3][4][5] and magnetic proximity effect where a magnetic insulator (MI) adlayer induces exchange coupling [3,[6][7][8]. Doping TM impurities into a TI will introduce a perpendicular ferromagnetic (FM) anisotropy and provide a straightforward means to open up the band gap of a TI's surface state, with profound influence to its electronic structure [4,[9][10][11][12][13][14]. In particular, quantum anomalous Hall effect (QAHE), where quantum Hall plateau and dissipationless chiral edge channels emerge at zero external magnetic field, has recently been realized in Cr-doped and V-doped TIs [9,10,[15][16][17][18][19][20]. Ideally, compared to the doping method, proximity effect has a number of advantages, including spatially uniform magnetization, better controllability of surface state, freedom from dopant-induced scattering, as well as preserving TI intrinsic crystalline structure, etc. [21,22]. However, due to the inplane anisotropy and low Curie temperature, such MIs are usually too weak to induce strong proximity magnetism in a TI. In fact, compared to a magnetically doped TI which can induce as large as a 50 meV surface band gap [4], the EuS-TI system has only a 7 meV gap opening due to the strongly localized Eu f orbitals [23]. Therefore, the enhancement of proximity magnetism is highly desirable to make it a valuable approach as doping hence takes full advantage.In this Letter, we report significant enhancement of the proximity effect in MI EuS/magnetic-TI Sb 2−x V x Te 3 hybrid heterostructure. Using polarized neutron reflectometry (PNR), we inferred an increase of proximity magnetization per unit cell (u.c.) in TI, from 1.2μ B =u:c. to 2.7μ B =u:c. at x ¼ 0.1 doping level. High-resolution transmission electron microscopy (HRTEM) identifies the TI-EuS interfacial sharpness and excludes the false positive magnetism signal from interdiffused Eu ions into a TI. Furthermore, the proximity effect enhancement is accompanied by a decrease of the interfacial magnetization of EuS, resulting in an exotic antiferro...

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Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 74%

mentioning

confidence: 99%

Proximity-Driven Enhanced Magnetic Order at Ferromagnetic-Insulator–Magnetic-Topological-Insulator Interface

Chang

Kirby

et al. 2015

Phys. Rev. Lett.

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“…Heterostructure of a TI with a magnetic insulator can lead to a large magnetic gap in the topological surface state. (Luo and Qi 2013;Eremeev et al 2013) …”

Section: Iif Topological Properties and Protectionsmentioning

confidence: 99%

Colloquium: Topological band theory

2016

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The first-principles band theory paradigm has been a key player not only in the process of discovering new classes of topologically interesting materials, but also for identifying salient characteristics of topological states, enabling direct and sharpened confrontation between theory and experiment. We begin this review by discussing underpinnings of the topological band theory, which basically involves a layer of analysis and interpretation for assessing topological properties of band structures beyond the standard band theory construct. Methods for evaluating topological invariants are delineated, including crystals without inversion symmetry and interacting systems. The extent to which theoretically predicted properties and protections of topological states have been verified experimentally is discussed, including work on topological crystalline insulators, disorder/interaction driven topological insulators (TIs), topological superconductors, Weyl semimetal phases, and topological phase transitions. Successful strategies for new materials discovery process are outlined. A comprehensive survey of currently predicted 2D and 3D topological materials is provided. This includes binary, ternary and quaternary compounds, transition metal and f-electron materials, Weyl and 3D Dirac semimetals, complex oxides, organometallics, skutterudites and antiperovskites. Also included is the emerging area of 2D atomically thin films beyond graphene of various elements and their alloys, functional thin films, multilayer systems, and ultra-thin films of 3D TIs, all of which hold exciting promise of wide-ranging applications. We conclude by giving a perspective on research directions where further work will broadly benefit the topological materials field.

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“…As an antiparallel magnetic structure with a low magnetic susceptibility, AFMs have negligible net magnetization 13,14 . Consequently, in a AFM/MTI heterostructure, the full spectrum of topological surface states may be easily modified through the strong exchange field of the AFM without invoking significant spin-dependent scattering on magnetic ions 15,16 . Furthermore, as AFM moments are relatively insensitive to external magnetic fields, the magnetism in such a heterostructure is resistant to external perturbations.…”

mentioning

confidence: 99%

Tailoring exchange couplings in magnetic topological-insulator/antiferromagnet heterostructures

et al. 2016

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Magnetic proximity effect at the three-dimensional topological insulator/magnetic insulator interface

Cited by 165 publications

References 40 publications

Proximity-Driven Enhanced Magnetic Order at Ferromagnetic-Insulator–Magnetic-Topological-Insulator Interface

Proximity-Driven Enhanced Magnetic Order at Ferromagnetic-Insulator–Magnetic-Topological-Insulator Interface

Colloquium: Topological band theory

Tailoring exchange couplings in magnetic topological-insulator/antiferromagnet heterostructures

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