AC Response of the Edge States in a Two‐Dimensional Topological Insulator Coupled to a Conducting Puddle

Abstract

We calculate an AC response of the edge states of a two-dimensional topological insulator, which can exchange electrons with a conducting puddle in the bulk of the insulator. This exchange leads to finite corrections to the response of isolated edge states both at low and high frequencies. By comparing these corrections, one may determine the parameters of the puddle.

Sub- to Super-Poissonian crossover of current noise in helical edge states coupled to a spin impurity in a magnetic field

“…Transport in helical Luttinger liquids is sensitive to the coupling to magnetic impurities [19][20][21][22][23]29,30 , and in particular, certain details of the dynamics of the impurities become visible in the transport current through the edge.…”

“…Unlike in the quantum Hall effect where different transport directions are spatially separated by the insulating bulk, in the QSHI left-and rightmovers exist on the same edge. Breaking TRS [7][8][9] or allowing for electron-electron interactions 8,[10][11][12][13] , electronphonon interactions 14,15 or interactions with nuclei 16 as well as with nearby charge puddles [17][18][19] induces backscattering corrections to the ballistic conductance value. Understanding such mechanism can explain some experimental deviations from the ballistic value but can also give insight to the nature of the helical edges states.…”

“…25 Bunching effects due to correlations between cotunneling processes are well studied in quantum dots and molecular magnets 26,27 . Noise from backscattering events off a spin impurity in helical liquids has been considered so far in the absence of magnetic fields, where the Fano factor is always larger than one, pointing at bunching behavior 19,[28][29][30] . Here, we show that in the presence of a Zeeman-field ∆ Z on the quantum dot, the bunching behavior becomes supplemented by an anti-bunching behavior for small tilt angles of the magnetic field for bias voltages that satisfy k B T < ∆ Z eV (for only one polarity of the bias voltage) where T is the temperature.…”

Влияние электрон-дырочной асимметрии на электронную структуру спиральных краевых состояний в квантовой яме HgTe/HgCdTe

“…Изучение спиральных краевых состояний, возникающих на краю двумерных топологических изоляторов, является важной областью физики двумерных кристаллических систем с нетривиальными топологическими свойствами [1][2][3]. К ключевым направлениям исследований можно отнести изучение локального и нелокального электронного транспорта по краевым каналам [4][5][6][7], механизмов рассеяния назад [8][9][10][11][12][13][14] и фотогальванического эффекта [15,16]. Среди различных систем, на краях которых экспериментально обнаружены одномерные спиральные каналы [2,3,17], наибольшее внимание привлекают квантовые ямы HgTe/HgCdTe.…”

Effects of Electron-Hole Asymmetry on Electronic Structure of Helical Edge States in HgTe/HgCdTe Quantum Wells

“…The study of helical edge states emerging at the edge of two-dimensional topological insulators is an important area of physics of two-dimensional crystalline systems with nontrivial topological properties [1][2][3]. The key areas of research include the study of local and nonlocal electron transport through edge channels [4][5][6][7], backscattering mechanisms [8][9][10][11][12][13][14] and photogalvanic effect [15,16]. Among various systems, where one-dimensional helical channels are experimentally observed [2,3,17], HgTe/HgCdTe quantum wells attract the most attention.…”