Effective Hamiltonian for surface states of topological insulator thin films with hexagonal warping

Siu, Zhuo Bin; Tan, Seng Ghee; Jalil, M. B. A.

doi:10.1063/1.4943416

Cited by 9 publications

(5 citation statements)

References 12 publications

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“…magnetic field, the in-plane magnetization lifts the energy degeneracy between the states localized near the top, and those near the bottom, of the film [23]. The magnetization also leads to a k-space displacement of the two distinct Dirac cones corresponding to the states localized near the two surfaces even when hexagonal warping is present [38].…”

Section: Introductionmentioning

confidence: 98%

“…In the absence of the out-of-plane magnetic field, the in-plane magnetization lifts the energy degeneracy between the states localized near the top, and those near the bottom, of the film [23]. The magnetization also leads to a k-space displacement of the two distinct Dirac cones corresponding to the states localized near the two surfaces even when hexagonal warping is present [38]. It is very natural to expect that the application of the magnetic field will further modify the band structure and modulate the DOS of the system.…”

Section: Introductionmentioning

confidence: 99%

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Quantum Capacitance of a Topological Insulator-Ferromagnet Interface

Siu

Chowdhury

Jalil

et al. 2017

Sci Rep

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We study the quantum capacitance in a topological insulator thin film system magnetized in the in-plane direction in the presence of an out-of-plane magnetic field and hexagonal warping. To first order, the modification in quantum capacitance due to hexagonal warping compared to the clean case, where both the in-plane magnetization and hexagonal warping are absent, is always negative, and increases in magnitude monotonically with the energy difference from the charge neutrality point. In contrast, the change in the quantum capacitance due to in-plane magnetization oscillates with the energy in general, except when a certain relation between the inter-surface coupling, out of plane Zeeman energy splitting and magnetic field strength is satisfied. In this special case, the quantum capacitance remains unchanged by the in-plane magnetization for all energies.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Quantum Capacitance of a Topological Insulator-Ferromagnet Interface

Siu

Chowdhury

Jalil

et al. 2017

Sci Rep

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“…In general, the cubic SOC terms play a key role in inducing non-linear spin and current responses. For example, it has been predicted that the trigonal warping term in transition metal dichalogenides can give rise to non-linear spin currents [6], whereas in the topological insualtor Bi 2 Te 3 , the experimentally observed nonlinear magnetoresistance [3] and Hall current [7] were attributed to the hexagonal warping [26][27][28] of its Fermi surface due to cubic SOC terms. However, to the best of our knowledge, the effects of these cubic Rashba terms on the second-order transport phenomena such as the transverse charge current and spin accumulation have not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

Second-order charge and spin transport in LaO/STO system in the presence of cubic Rashba spin orbit couplings

Bin Siu,

Kundu,

Jalil

2024

New J. Phys.

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Certain non-centrosymmetric materials with broken time-reversal symmetry may exhibit non-reciprocal transport behavior under an applied electric ﬁeld in which the charge and spin currents contain components that are second order in the electric ﬁeld. In this study, we investigate the second-order spin accumulation and charge and spin responses in the LaAlO3/SrTiO3 (LaO/STO) system with magnetic dopants under the inﬂuence of linear and cubic Rashba spin‒orbit coupling (RSOC) terms. We explain the physical origin of the second-order response and perform a symmetry analysis of the ﬁrst and second-order responses for diﬀerent dopant magnetization directions relative to the applied electric ﬁeld. We then numerically solve the Boltzmann transport equation by extending the approach of Schliemann and Loss [Phys. Rev. B 68, 165311] to higher orders in the electric ﬁeld. We show that the sign of the second-order responses can be switched by varying the magnetization direction of the magnetic dopants or relative strengths of the two cubic RSOC terms and explain these trends by considering the Fermi surfaces of the respective systems. These ﬁndings provide insights into the interplay of multiple SOC eﬀects in a LaO/STO system and how the resulting ﬁrst- and second-order charge and spin responses can be engineered by exploiting the symmetries of the system.

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“…Fu confirms that to maintain the bulk topological invariance, there should exist out-of-the-plane components of the spins to conserve the net value of Berrys phase, and this out of plane component of the Berry phase can only be explained in the presence of a hexagonally deformed cone of the TIs. Incorporation of this hexagonal warping term provides new possibilities to connect with the spintronics application based studies in TIs [12,13]. It turns out that the hybridization term describing the surface state interaction also plays a very crucial role in explaining the quantum phase transition(QPT) in presence of a parallel magnetic field [14], wherein the coupling between hybridization term and magnetic field term gives rise to the semimetal to insulator phase transition.…”

Section: Introductionmentioning

confidence: 99%

Hybridization and Field Driven Phase Transitions in Hexagonally Warped Topological Insulators

Menon

Chowdhury

Basu

2016

SPIN

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In this paper we discuss the role of material parameters and external field effects on a thin film topological insulator(TI) in the context of quantum phase transition(QPT). First, we consider an in-plane tilted magnetic field and determine the band structure of the surface states as a function of the tilt angle. We show that the presence of either a hybridization term or hexagonal warping or a combination of both leads to a semi-metal to insulator phase transition which is facilitated by their PT symmetry breaking character. We then note that while the introduction of an electric field does not allow for this QPT since it doesn't break PT symmetry, it can be used in conjunction with a tunneling element to reach a phase transition efficiently. The corresponding critical point is then non-trivially depend on the electric field, which is pointed out here. Then, we demonstrate that including a hexagonal warping term leads to an immediate PT symmetry violating QPT.

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Effective Hamiltonian for surface states of topological insulator thin films with hexagonal warping

Cited by 9 publications

References 12 publications

Quantum Capacitance of a Topological Insulator-Ferromagnet Interface

Quantum Capacitance of a Topological Insulator-Ferromagnet Interface

Second-order charge and spin transport in LaO/STO system in the presence of cubic Rashba spin orbit couplings

Hybridization and Field Driven Phase Transitions in Hexagonally Warped Topological Insulators

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