Anderson impurity in the bulk of topological insulators

Kuzmenko, Igor; Avishai, Y.; Ng, Tai Kai

doi:10.1103/physrevb.89.035125

Cited by 9 publications

(10 citation statements)

References 43 publications

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“…We note that most theoretical studies were based on a simple model of classic magnetic impurities with fixed magnetization. However, a magnetic impurity usually exhibits quantum behavior and spin dynamics, and so should be treated as quantum entities [18][19][20][21][22]. One of the remarkable merits of the quantum impurity model can be seen by considering the effect of internal degrees of freedom of impurities, such as magnetic excitations and localized vibrational modes.…”

Section: Introductionmentioning

confidence: 99%

Electrically tunable Dirac-point resonance induced by a nanomagnet absorbed on the topological insulator surface

et al. 2015

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We investigate the effect of spin-inelastic scattering of Dirac electrons off a high-spin nanomagnet adsorbed on a topological insulator (TI) surface, in which transitions of the nanomagnet between its internal magnetic levels are taken into account, beyond the classic spin theory. It is found that the presence of magnetic anisotropy of nanomagnets can result in a Dirac-point resonance peak in local density of states. It can significantly modify the topologically protected Dirac surface-state spectrum at the Dirac point, quite different from previously reported low-energy resonances. Furthermore, we propose to tune electrically the appearance of the Dirac-point resonance peak and its height by use of the spin-flip torque effect. This provides an approach to engineer the Dirac cone and tune the Dirac electron properties on the TI surface in the absence of an external magnetic field.

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Section: Introductionmentioning

confidence: 99%

Electrically tunable Dirac-point resonance induced by a nanomagnet absorbed on the topological insulator surface

et al. 2015

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“…The Dirac/Weyl semimetals with a linear dispersion in d spatial dimensions correspond to a pseudogap system with the aforementioned exponent r = d − 1 2. In[66][67][68] the excitation gap in the bulk has the form of a Dirac mass, rather than a Majorana mass generated from Cooper pairing.…”

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confidence: 99%

Overscreened Kondo effect, (color) superconductivity, and Shiba states in Dirac metals and quark matter

Kanazawa

Uchino

2016

Phys. Rev. D

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We study the interplay between the Kondo effect and (color) superconductivity in doped Dirac metals with magnetic impurities and in quark matter with colorful impurities. We first point out that the overscreened Kondo effect arises in the normal state of these systems. Next the (color) superconducting gap is incorporated as a mean field and the phase diagram for a varying gap and temperature is constructed nonperturbatively. A rich phase structure emerges from a competition of effects unique to a multichannel system. The Kondo-screened phase is shown to disappear for a sufficiently large gap. Peculiarity of quark matter due to the confining property of non-Abelian gauge fields is noted. We also investigate the spectrum of sub-gap excited states, called Shiba states. Based on a model calculation and physical reasoning we predict that, as the coupling of the impurity to the bulk is increased, there will be more than one quantum phase transition due to level crossing among overscreened states.

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“…[50][51][52] In addition, there are many other researches studying the quantum effect induced by magnetic impurities on the surface of TIs. [53][54][55][56][57][58] However the study of Kondo effect in TIQDs is still sparse. Because of the intrinsic spin-orbital locking feature existed in TI materials, a TIQD is a natural candidate to realize the spin-orbital Kondo effect.…”

Section: Introductionmentioning

confidence: 99%

Kondo effect in a topological insulator quantum dot

Xin

Zhou

2015

Phys. Rev. B

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We investigate the non-equilibrium transport properties of a topological insulator quantum dot (TIQD) in the Coulomb blockade and Kondo regime theoretically. An Anderson impurity model is applied to a TIQD system coupled to two external leads, and we show that the model realizes the spin-orbital Kondo effect at Dirac point where the edge states are not split by a finite-size effect, leading to an additional SU (4) symmetry because of the presence of strong mixture among four internal degrees of freedom. In a more realistic situation where the degeneracy is lifted due to the finite-size effect, we demonstrate that there is a richer structure in transport measurements. We illustrate a continuous crossover from four (spin and orbital) Coulomb peaks with large inter-pair spacing and small intra-pair spacing to a double-peak structure in the local density of states (LDOS) as increasing the hybridization strength Γ within the Coulomb blockade regime. When temperature falls below the Kondo temperature TK , four Kondo peaks show up in the non-equilibrium LDOS. Two of them are located at the chemical potential of each lead, and the other two are shift away from the chemical potential by the amount proportional to the TIQD's bare energy level, leading to a triple-peak structure in the differential conductance when a bias voltage is applied.

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Anderson impurity in the bulk of topological insulators

Cited by 9 publications

References 43 publications

Electrically tunable Dirac-point resonance induced by a nanomagnet absorbed on the topological insulator surface

Electrically tunable Dirac-point resonance induced by a nanomagnet absorbed on the topological insulator surface

Overscreened Kondo effect, (color) superconductivity, and Shiba states in Dirac metals and quark matter

Kondo effect in a topological insulator quantum dot

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