Determining the strength of magnetic and potential scattering of magnetic impurities on the surface of a topological insulator via quantum corrals

Zheng, Cheng; Li, Q. L.; Miao, B. F.; Sun, L. Z.; Wang, R.; Li, X. X.; Ding, Haifeng

doi:10.1103/physrevb.96.235444

Cited by 5 publications

(3 citation statements)

References 49 publications

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“…Following Ref. 45, which compared the LDOS with scanning tunnelling spectroscopy results, one can find that the strength of impurity potentials, m and u can vary between 0.3−3 and 3−30, respectively. This shows the practical importance of u for different magnetic impurities.…”

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confidence: 90%

Nonlinear spin susceptibility in topological insulators

et al. 2018

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We revise the theory of the indirect exchange interaction between magnetic impurities beyond the linear response theory to establish the effect of impurity resonances in the surface states of a three dimensional topological insulator. The interaction is composed of an isotropic Heisenberg, anisotropic Ising and Dzyaloshinskii-Moriya-type of couplings. We find that all three contributions are finite at the Dirac point, which is in stark contrast to the linear response theory which predicts a vanishing Dzyaloshinskii-Moriya-type contribution. We show that the spin-independent component of the impurity scattering can generate large values of the Dzyaloshinskii-Moriya-type coupling in comparison with the Heisenberg and Ising types of coupling, while these latter contributions drastically reduce in magnitude and undergo sign changes. As a result, both collinear and non-collinear configurations are allowed magnetic configurations of the impurities.

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confidence: 90%

Nonlinear spin susceptibility in topological insulators

et al. 2018

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“…We find these values by comparing our spin-resolved LDOS with the results of Refs. [30][31][32][33] . To simplify our plots we express the coupling terms, J, and spin-resolved LDOS in units of (J c /h 2 v 2 F Ω BZ ) 2 and 1/h 2 v 2…”

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confidence: 99%

Highly tunable magnetic coupling in ultrathin topological insulator films due to impurity resonances

Shiranzaei,

Fransson,

Black-Schaffer

et al. 2020

Preprint

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We theoretically investigate the exchange interaction between magnetic impurities in ultrathin Bi 2 Se 3 topological insulator films by taking into account the low-energy states produced by the impurities. We find that the locally induced impurity resonances strongly influence the exchange interaction between magnetic moments. In particular, we find a non-collinear alignment being more favorable than the collinear ferromagnetic alignment preferred when impurity states are ignored and only the pristine topological insulator band structure is considered. Moreover, we show that by applying of an electric field perpendicular to the ultrathin film, the exchange interaction can be drastically enhanced. This opens for the possibility of highly tunable magnetism by electric field.

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“…This violates the fundamental theory of TIs which asserts the robustness of the gapless Dirac cone in the non-magnetic state. In theory, impurity resonant states were proposed to be responsible for such modification of the local electronic structure and the non-magnetic gap at the DP [12][13][14][15][16][17][18][19][20][21]. At present, however, the debate about exact nature of the non-magnetic gap continues due to the lack of photoemission experiments addressing the appearance of an energy gap in photoemission experiments without ferromagnetic order, which is inconsistency is still awaiting to be experimentally resolved.…”

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confidence: 99%

Gap-like feature observed in the non-magnetic topological insulators

Yilmaz

Pertsova²,

Hines³

et al. 2020

J. Phys.: Condens. Matter

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Non-magnetic gap at the Dirac point of topological insulators remains an open question in the field. Here, we present angle-resolved photoemission spectroscopy experiments performed on Cr-doped Bi 2 Se 3 and showed that the Dirac point is progressively buried by the bulk bands and a low spectral weight region in the vicinity of the Dirac point appears. These two mechanisms lead to spectral weight suppression region being mistakenly identified as an energy gap in earlier studies. We further calculated the band structure and found that the original Dirac point splits into two nodes due to the impurity resonant states and the energy separation between the nodes is the low density of state region which appears to be like an energy gap in potoemission experiments. We supported our arguments by presenting photoemission experiments carried out with on-and off-resonant photon energies. Our observation resolves the widely debated questions of apparent energy gap opening at the Dirac point without long range ferromagnetic order in topological insulators.

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Determining the strength of magnetic and potential scattering of magnetic impurities on the surface of a topological insulator via quantum corrals

Cited by 5 publications

References 49 publications

Nonlinear spin susceptibility in topological insulators

Nonlinear spin susceptibility in topological insulators

Highly tunable magnetic coupling in ultrathin topological insulator films due to impurity resonances

Gap-like feature observed in the non-magnetic topological insulators

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