Simple mechanisms that impede the Berry phase identification from magneto-oscillations

Kuntsevich, A. Yu.; Shupletsov, A. V.; Minkov, G. M.

doi:10.1103/physrevb.97.195431

Cited by 13 publications

(14 citation statements)

References 43 publications

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“…Another indication of grain boundaries (suggested in [31]) is seen from the magnetotransport in perpendicular magnetic field. Figure 4(d) shows magnetoresistance and Hall resistance at 2 K for sample Sr 0.15 Bi 2 Se 3 #308-3.…”

Section: Structural Studies: Block Structurementioning

confidence: 88%

Structural distortion behind the nematic superconductivity in Sr_xBi₂Se₃

et al. 2018

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An archetypical layered topological insulator Bi 2 Se 3 becomes superconductive upon doping with Sr, Nb or Cu. Superconducting properties of these materials in the presence of in-plane magnetic field demonstrate spontaneous symmetry breaking: 180 • -rotation symmetry of superconductivity versus 120 • -rotation symmetry of the crystal. Such behavior brilliantly confirms nematic topological superconductivity. To what extent this nematicity is due to superconducting pairing in these materials, rather than due to crystal structure distortions? This question remains unanswered, because so far no visible deviations from the 3-fold crystal symmetry were resolved in these materials. To address this question we grow high quality single crystals of Sr x Bi 2 Se 3 , perform detailed x-ray diffraction and magnetotransport studies and reveal that the observed superconducting nematicity direction correlates with the direction of small structural distortions in these samples (∼0.02% elongation in one crystallographic direction). Additional anisotropy comes from orientation of the crystallite axes. 2-fold symmetry of magnetoresistance observed in the most uniform crystals well above the critical temperature demonstrates that these structural distortions are nevertheless strong enough. Our data in combination with strong sample-to-sample variation of the superconductive anisotropy parameter are indicative for significance of the structural factor in the apparent nematic superconductivity in Sr x Bi 2 Se 3 .

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Section: Structural Studies: Block Structurementioning

confidence: 88%

Structural distortion behind the nematic superconductivity in Sr_xBi₂Se₃

et al. 2018

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“…A large number of carriers in 3D multiband systems pin the chemical potential. In 2018, Kuntsevich et al phenomenologically explained that, even when a large number of carriers in normal bands pin the chemical potential, the SdH oscillation of the Dirac (linear) dispersion should show the π phase shift 76 . Here, we will explain why the chemical potential pinning does not affect the phase shift in the SdH oscillations, along with ref.…”

Section: Methodsmentioning

confidence: 99%

Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide

et al. 2020

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Magnetic Weyl semimetals have novel transport phenomena related to pairs of Weyl nodes in the band structure. Although the existence of Weyl fermions is expected in various oxides, the evidence of Weyl fermions in oxide materials remains elusive. Here we show direct quantum transport evidence of Weyl fermions in an epitaxial 4d ferromagnetic oxide SrRuO3. We employ machine-learning-assisted molecular beam epitaxy to synthesize SrRuO3 films whose quality is sufficiently high to probe their intrinsic transport properties. Experimental observation of the five transport signatures of Weyl fermions—the linear positive magnetoresistance, chiral-anomaly-induced negative magnetoresistance, π phase shift in a quantum oscillation, light cyclotron mass, and high quantum mobility of about 10,000 cm2V−1s−1—combined with first-principles electronic structure calculations establishes SrRuO3 as a magnetic Weyl semimetal. We also clarify the disorder dependence of the transport of the Weyl fermions, which gives a clear guideline for accessing the topologically nontrivial transport phenomena.

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“…An important consequence of the phase slips is that the intercept γ for 1/B ⊥ → 0 in an index plot ν(1/B ⊥ ) is not meaningful. The method for extracting Berry's phase in Dirac materials like graphene or three-dimensional topological insulator surface states from quantum oscillations by 1/B ⊥ → 0 extrapolation [25][26][27][28] is not applicable here. More generally, in a fully quantized twodimensional system, γ is either 0 or 1/2.…”

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confidence: 99%

Phase slips and parity jumps in quantum oscillations of inverted InAs/GaSb quantum wells

et al. 2019

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We present magnetotransport measurements of a strongly hybridized inverted InAs/GaSb double quantum well. We find that the spin-orbit interaction leads to an appreciable spin-splitting of hole-like states, which form distinct Landau levels in a perpendicular magnetic field. The resulting quantum Hall state is governed by a periodic even and odd total filling arising due to the simultaneous occupation of electron-like and hole-like Landau levels of differing degeneracy. Furthermore, oscillatory charge transfer between all involved subbands leads to discrete phase slips in the usual sequential filling of Landau levels, and coincidentally the phase slips are close to π. These results shed new insights on the Landau level structure in composite systems and have consequences for interpreting intercepts obtained from index plots, which are routinely employed to investigate the presence of Berry's phase.InAs/GaSb double quantum wells (QWs) are a composite semiconductor system that hosts spatially separated electrons and holes and exhibits significant spinorbit interaction (SOI). The thicknesses of the constituent InAs and GaSb QWs determine the band alignment, which may be either inverted or noninverted. Application of electric and magnetic fields offers additional tunability, allowing for continuous control of this band alignment [1][2][3]. In the inverted phase, electrons and holes hybridize, opening an energy gap [4][5][6], which facilitates the formation of the quantum spin Hall insulator (QSHI) state under the right conditions [7][8][9][10][11][12].The inverted band structure and tunability of InAs/GaSb double QWs enable many interesting experiments not directly related to the QSHI state, such as the manipulation of the SOI in single-and two-carrier regimes [13], the observation of a giant spin-orbit splitting close to the charge neutrality point (CNP) [14] and tunable mixing of quantum Hall (QH) edge states [15].Here, we report our findings on the Landau level (LL) structure in a strongly inverted InAs/GaSb double QW featuring enhanced hybridization. Using transport measurements we uncover a periodic even and odd filling of Landau levels leading to a checkerboard pattern in the longitudinal resistivity ρ xx . Additionally, an anomalous shift violates the usual 1/B ⊥ -periodic sequence of LL filling. By analyzing Shubnikov-de Haas (SdH) oscillations and performing two and three-band transport modeling, we unravel the electron and hole-like charge carrier distribution in the system, thereby deducing the presence of an initially concealed SOI split hole-like subband. We then explain how the combination of SOI induced splitting and Landau quantization can lead to an unconventional filling sequence of LLs in this coupled electron-hole bilayer.Measurements were performed on a gated Hall bar of 10 µm width and 20 µm length oriented along the [011] crystallographic direction on a heterostructure consisting of an 8 nm GaSb QW and a 13.5 nm InAs QW [ Fig. 1(a)]. The Hall bar was defined by wet etching and covered by a SiN l...

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Simple mechanisms that impede the Berry phase identification from magneto-oscillations

Cited by 13 publications

References 43 publications

Structural distortion behind the nematic superconductivity in Sr_xBi₂Se₃

Structural distortion behind the nematic superconductivity in Sr_xBi₂Se₃

Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide

Phase slips and parity jumps in quantum oscillations of inverted InAs/GaSb quantum wells

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Simple mechanisms that impede the Berry phase identification from magneto-oscillations

Cited by 13 publications

References 43 publications

Structural distortion behind the nematic superconductivity in Sr x Bi2Se3

Structural distortion behind the nematic superconductivity in Sr x Bi2Se3

Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide

Phase slips and parity jumps in quantum oscillations of inverted InAs/GaSb quantum wells

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Structural distortion behind the nematic superconductivity in Sr_xBi₂Se₃

Structural distortion behind the nematic superconductivity in Sr_xBi₂Se₃