Topological Insulators in Two Dimensions

Wiedmann, Steffen; Molenkamp, L. W.

doi:10.1002/9783527681594.ch3

Cited by 10 publications

(40 citation statements)

References 57 publications

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“…The geometric curvature is a gauge-invariant local manifestation of the geometry of quant um states that depend on parameters. It is a physical ingredient for understanding a variety of electronic properties [14], including electric polarisation [15], charge and spin transport [7], anomalous Hall effect [16], topological insulators and superconductors [17][18][19] and topological photonics [20]. This body of research indicates that the curvature can influence the physics in a number of ways (for example via the Chern number [3]).…”

Section: Discussionmentioning

confidence: 99%

Geometric phase curvature for random states

Berry

Shukla

2018

J. Phys. A: Math. Theor.

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The probability distribution of the geometric curvature C (2-form) governing the geometric phase of transported quantum states is calculated for N × N matrix Hamiltonians generated from the Gaussian unitary ensemble, and depending on two parameters x, y. The distributions take the form of scaling functions, different for N = 2 and N > 2 but both decaying asymptotically as 1/|C| 5/2 , with scalings depending on x, y and N.

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Section: Discussionmentioning

confidence: 99%

Geometric phase curvature for random states

Berry

Shukla

2018

J. Phys. A: Math. Theor.

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“…From scanning tunnelling microscopy studies of Dirac fermionmediated magnetic order, it was concluded that the anisotropy of the dopant and their consequences for the Fermi level are crucial [62]. In some systems, the TSS-mediated RKKYtype interaction has been used as a possible explanation for the inconsistencies between surface-sensitive and bulk-sensitive measurements [22].…”

Section: Discussionmentioning

confidence: 99%

“…Establishing ferromagnetic order in the prototypical 3D TIs Bi 2 Se 3 and Bi 2 Te 3 has been achieved using 3d transition metal dopants such as Mn [15][16][17] and Cr [18,19]. However, uncontrollable formation of parasitic phases and inconsistent results among various complimentary measurement techniques which probe longrange ferromagnetic order and modifications in the surface states, have been reported [9,15,[20][21][22]. Cr has by far been the most successful transition metal dopant as the first experimentally detected QAHE was achieved at mK temperatures in Cr-doped (Bi,Sb) 2 Te 3 (T C = 15 K) [23].…”

Section: Introductionmentioning

confidence: 99%

Study of Dy-doped Bi₂Te₃: thin film growth and magnetic properties

Harrison

Collins-McIntyre

Zhang

et al. 2015

J. Phys.: Condens. Matter

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Abstract. Breaking the time-reversal symmetry (TRS) in topological insulators (TIs) through ferromagnetic doping is an essential prerequisite for unlocking novel physical phenomena and exploring potential device applications. Here, we report the successful growth of high-quality (Dy x Bi 1−x ) 2 Te 3 thin films with Dy concentrations up to x = 0.355 by molecular beam epitaxy. Bulk-sensitive magnetisation studies using superconducting quantum interference device magnetometry find paramagnetic behaviour down to 2 K for the entire doping series. The effective magnetic moment, µ eff , is strongly doping concentration-dependent and reduces from ∼12.6 µ B /Dy for x = 0.023 to ∼4.3 µ B /Dy for x = 0.355. X-ray absorption spectra and x-ray magnetic circular dichroism (XMCD) at the Dy M 4,5 edge are employed to provide a deeper insight into the magnetic nature of the Dy 3+ -doped films. XMCD, measured in surfacesensitive total-electron-yield detection, gives µ eff = 4.2 µ B /Dy. The large measured moments make Dy-doped films interesting TI systems in which the TRS may be broken via the proximity effect due to an adjacent ferromagnetic insulator.

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“…The mechanism behind the appearance of these states is the bulk band inversion due to strong spin-orbit coupling. These classes of materials possess massless helical surface states which have topological protection against the non-magnetic disorder due to the presence of time reversal symmetry and a π Berry phase [3]. The helical nature of the surface states guarantees the absence of the backscattering from disorder as opposed to the trivial 2D electron gas systems which localize the electrons in the presence of disorder at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Linear magnetoresistance and surface to bulk coupling in topological insulator thin films

Singh¹,

Gopal²,

Sarkar³

et al. 2017

J. Phys.: Condens. Matter

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We explore the temperature dependent magnetoresistance of bulk insulating topological insulator thin films. Thin films of BiSeTe and BiSbTeSe were grown using the pulsed laser deposition technique and subjected to transport measurements. Magnetotransport measurements indicate a non-saturating linear magnetoresistance (LMR) behavior at high magnetic field values. We present a careful analysis to explain the origin of LMR taking into consideration all the existing models of LMR. Here we consider that the bulk insulating states and the metallic surface states constitute two parallel conduction channels. Invoking this, we were able to explain linear magnetoresistance behavior as a competition between these parallel channels. We observe that the cross-over field, where LMR sets in, decreases with increasing temperature. We propose that this cross-over field can be used phenomenologically to estimate the strength of surface to bulk coupling.

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Topological Insulators in Two Dimensions

Cited by 10 publications

References 57 publications

Geometric phase curvature for random states

Geometric phase curvature for random states

Study of Dy-doped Bi₂Te₃: thin film growth and magnetic properties

Linear magnetoresistance and surface to bulk coupling in topological insulator thin films

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Topological Insulators in Two Dimensions

Cited by 10 publications

References 57 publications

Geometric phase curvature for random states

Geometric phase curvature for random states

Study of Dy-doped Bi2Te3: thin film growth and magnetic properties

Linear magnetoresistance and surface to bulk coupling in topological insulator thin films

Contact Info

Product

Resources

About

Study of Dy-doped Bi₂Te₃: thin film growth and magnetic properties