Magnetic proximity effect and interlayer exchange coupling of ferromagnetic/topological insulator/ferromagnetic trilayer

Li, Mingda; Cui, Wenping; Yu, Jie; Dai, Zuyang; Wang, Zhe; Katmis, Ferhat; Guo, Wanlin; Moodera, Jagadeesh S.

doi:10.1103/physrevb.91.014427

Cited by 52 publications

(41 citation statements)

References 57 publications

(91 reference statements)

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“…z is the vertical distance between Mn and Cr, which we set to their mean distance in a magnetic TI layer as z = ( m + c )/2. The calculated sign of J mc eff ( z ) oscillates as a function of z [30], is listed in Table I. The sign of J mc eff is opposite to that in Ref.…”

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confidence: 80%

Dynamical axion field in a magnetic topological insulator superlattice

2016

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We propose that the dynamical axion field can be realized in a magnetic topological insulator superlattice or a topological paramagnetic insulator. The magnetic fluctuations of these systems produce a pseudoscalar field which has an axionic coupling to the electromagnetic field, and thus it gives a condensed-matter realization of the axion electrodynamics. Compared to the previously proposed dynamical axion materials where a long range antiferromagnetic order is required, the systems proposed here have the advantage that only a uniform magnetization or a paramagnetic state is needed for the dynamic axion. We further propose several experiments to detect such a dynamical axion field.

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confidence: 80%

Dynamical axion field in a magnetic topological insulator superlattice

2016

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“…7, which has a wide application in designing MRAM memories and magnetic read heads, biosensor and MEMS device etc. A lot of experiments have been carried out using polarized neutron reflectometry (PNR) tool which clearly illustrates Fe/Cr superlattices that led to GMR effect [36] but PNR has some limitations also [37].…”

Section: Gmrmentioning

confidence: 99%

Spintronics: A contemporary review of emerging electronics devices

Joshi

2016

Engineering Science and Technology, an International Journal

135

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“…The DM interaction has the possible forms, E b dmi = n · (∇ × n) or E n dmi = n z ∇ · n − n · ∇n z , depending on whether d 1 or d 2 arises in the Dirac Hamiltonian (1). The latter is more adequate for Bi 2 Se 3 -EuS samples [13]. The ab initio results from Ref.…”

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confidence: 95%

“…This happens for instance when time-reversal (TR) symmetry is broken, which renders the surface Dirac fermions gapped. This can be achieved, for example, by proximity-effect with a ferromagnetic insulator (FMI) [5][6][7][8][9][10][11][12][13][14][15]. In this case, a CS term is generated if there are an odd number of gapped Dirac fermions, which is achieved only in the presence of out-of-plane exchange fields [11].…”

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confidence: 99%

Fluctuation-induced Néel and Bloch skyrmions at topological insulator surfaces

et al. 2018

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Ferromagnets in contact with a topological insulator have become appealing candidates for spintronics due to the presence of Dirac surface states with spin-momentum locking. Because of this, bilayer Bi 2 Se 3 -EuS structures, for instance, show a finite magnetization at the interface at temperatures well exceeding the Curie temperature of bulk EuS. Here, we determine theoretically the effective magnetic interactions at a topological insulator-ferromagnet interface above the magnetic ordering temperature. We show that by integrating out the Dirac fermion fluctuations an effective Dzyaloshinskii-Moriya interaction and magnetic charging interaction emerge. As a result, individual magnetic skyrmions and extended skyrmion lattices can form at the interfaces of ferromagnets and topological insulators, the first indications of which have been very recently observed experimentally. DOI: 10.1103/PhysRevB.98.060401Introduction. The spin-momentum locking property of three-dimensional topological insulators (TIs) [1,2] makes them promising candidate materials for future spin-based electronic devices. One important consequence of spin-momentum locking in TIs is the topological electromagnetic response, which arises from induced Chern-Simons (CS) terms [3] on each surface [4]. This happens, for instance, when timereversal (TR) symmetry is broken, which renders the surface Dirac fermions gapped. This can be achieved, for example, by a proximity effect with a ferromagnetic insulator (FMI) [5][6][7][8][9][10][11][12][13][14][15]. In this case, a CS term is generated if there are an odd number of gapped Dirac fermions, which is achieved only in the presence of out-of-plane exchange fields [11]. The realization of several physical effects related to the CS term that have been predicted in the literature critically depends on growing technologies required for the fabrication of heterostructures involving both strong TIs and FMIs. Recently, high-quality Bi 2 Se 3 -EuS bilayer structures have been shown to exhibit proximity-induced ferromagnetism on the surface of Bi 2 Se 3 [6,16,17]. Other successful realizations of stable ferromagnetic TI interfaces were demonstrated recently [18,19]. In addition, it was shown that the interface of FMI and TI can have a magnetic ordering temperature much higher than the bulk ordering temperature [5], indicating that topological surface states can strongly affect the magnetic properties of a proximity-coupled FMI.These experimental advances motivate us to investigate the effective magnetic interactions that result from the fluctuating momentum-locked Dirac fermion surface states of a TI in contact with an FMI.We show that even in the absence of any spontaneous magnetization, at temperatures above the Curie temperature

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Magnetic proximity effect and interlayer exchange coupling of ferromagnetic/topological insulator/ferromagnetic trilayer

Cited by 52 publications

References 57 publications

Dynamical axion field in a magnetic topological insulator superlattice

Dynamical axion field in a magnetic topological insulator superlattice

Spintronics: A contemporary review of emerging electronics devices

Fluctuation-induced Néel and Bloch skyrmions at topological insulator surfaces

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