Nonlinear spin susceptibility in topological insulators

Shiranzaei, Mahroo; Fransson, Jonas; Cheraghchi, Hosein; Parhizgar, Fariborz

doi:10.1103/physrevb.97.180402

Cited by 18 publications

(11 citation statements)

References 46 publications

(60 reference statements)

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“…The response of magnons to the perturbation in isotropic AFMs reveals that for low energy the defect on sublattice A, gives rise to the leakage of states into the sublattice B. This behaviour is as same as what one observes in a honeycomb lattice, e.g., graphene and FM Dirac magnons [29] and other Dirac materials [40,47].…”

Section: A Induced Resonance Peaksupporting

confidence: 66%

The impact of defects on low-energy excitations in two dimensional bipartite uniaxial antiferromagnet insulators

Shiranzaei¹,

Fransson²

2021

Preprint

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We address scattering of spin-wave through uncorrelated defects in two-dimensional (2D) easy-axis antiferromagnet (AFM) insulators. Although an on-site magnetic anisotropy leads to that the Goldstone modes become gapped bosons such that a long-range (AFM) order can be established in 2D, lattice imperfections have a tendency to weaken, and eventually destroy, the magnetic ordering. The impact of defects is considered within two limits, single and multiple defects. We apply the Green's function approach self-consistently to find magnon properties such as density of states and lifetime of induced resonances. Our findings show that repulsive defects decrease the magnon density of states while attractive ones may enhance it. We provide a comprehensive analysis of how defects can result in a reduction, and even closing, the anisotropy induced gap, which weakens the long-range (AFM) order parameter in the 2D state. We conclude that a small concentration of random defects can fill the gap of magnon spectrum.

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Section: A Induced Resonance Peaksupporting

confidence: 66%

The impact of defects on low-energy excitations in two dimensional bipartite uniaxial antiferromagnet insulators

Shiranzaei¹,

Fransson²

2021

Preprint

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“…Finally, we emphasize that the magnetic scattering potential may also happen in the presence of magnetic impurities. In such a situation, the RKKY interaction should be approached beyond the linear response theory and the local magnetization should also be considered 57,58 . This revises the theory of linear off-resonant RKKY interaction between magnetic impurities and considers the impact of impurity resonances.…”

Section: Discussionmentioning

confidence: 99%

Anisotropic Ferroelectric Distortion Effects on the RKKY Interaction in Topological Crystalline Insulators

Cheraghchi

Yarmohammadi

2020

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Manipulation of electronic and magnetic properties of topological materials is a topic of much interest in spintronic and valleytronic applications. Perturbation tuning of multiple Dirac cones on the (001) surface of topological crystalline insulators (TCIs) is also a related topic of growing interest. Here we show the numerical evidence for the ferroelectric structural distortion effects on the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between two magnetic impurity moments on the SnTe (001) and related alloys. The mirror symmetry breaking between Dirac cones induced by the ferroelectric distortion could be divided into various possible configurations including the isotropically gapped, coexistence of gapless and gapped, and anisotropically gapped phases. Based on the retarded perturbed Green’s functions of the generalized gapped Dirac model, we numerically find the RKKY response for each phase. The distortion-induced symmetry breaking constitutes complex and interesting magnetic responses between magnetic moments compared to the pristine TCIs. In the specific case of coexisted gapless and gapped phases, a nontrivial behavior of the RKKY interaction is observed, which has not been seen in other Dirac materials up until now. For two impurities resided on the same sublattices, depending on the distortion strength, magnetic orders above of a critical impurity separation exhibit irregular ferromagnetic $ antiferromagnetic phase transitions. However, independent ofthe impurity separation and distortion strength, no phase transition emerges for two impurities resided on different sublattices. This essential study sheds light on magnetic properties of Dirac materials with anisotropic mass terms and also makes TCIs applications relatively easy to understand.

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“…The results are valid under the rigid band approximation. Effects beyond this approximations have been discussed by Shiranzaei et al 84 Both RKKY theories discussed above assume the nonpolarized continuum of the mobile carriers mediating the indirect exchange interaction between the adatoms. However, in practice the impurity states have some spatial spillover on the graphene backbone and therefore a hybridization occurs and an impurity band develops with a typical width proportional to the coupling strength.…”

Section: Conventionalmentioning

confidence: 99%

Gate-tunable magnetism of C adatoms on graphene

et al. 2019

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We have performed density functional theory calculations of graphene decorated with carbon adatoms, which bind at the bridge site of a C-C bond. Earlier studies have shown that the C adatoms have magnetic moments and have suggested the possibility of ferromagnetism with high Curie temperature. Here we propose to use a gate voltage to fine tune the magnetic moments from zero to 1 µB while changing the magnetic coupling from antiferromagnetism to ferromagnetism and again to antiferromagnetism. These results are rationalized within the Stoner and RKKY models. When the SCAN meta-GGA correction is used, the magnetic moments for zero gate voltage are reduced and the Stoner band ferromagnetism is slightly weakened in the ferromagnetic region.

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Nonlinear spin susceptibility in topological insulators

Cited by 18 publications

References 46 publications

The impact of defects on low-energy excitations in two dimensional bipartite uniaxial antiferromagnet insulators

The impact of defects on low-energy excitations in two dimensional bipartite uniaxial antiferromagnet insulators

Anisotropic Ferroelectric Distortion Effects on the RKKY Interaction in Topological Crystalline Insulators

Gate-tunable magnetism of C adatoms on graphene

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