TY - JOUR

T1 - Sub- to Super-Poissonian crossover of current noise in helical edge states coupled to a spin impurity in a magnetic field

AU - Probst, Benedikt

AU - Virtanen, Pauli

AU - Recher, Patrik

N1 - Funding information: P.V. acknowledges funding from EU's Horizon 2020 research, from the innovation program under Grant Agreement No. 800923 (SUPERTED) and from Academy of Finland Project No. 317118. P.R. acknowledges financial support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the framework of Germany's Excellence Strategy–EXC-2123 QuantumFrontiers–390837967.

PY - 2022/8/4

Y1 - 2022/8/4

N2 - Edge states of two-dimensional topological insulators are helical and single-particle backscattering is prohibited by time-reversal symmetry. In this work, we show that an isotropic exchange coupling of helical edge states (HES) to a spin 1/2 impurity subjected to a magnetic field results in characteristic backscattering current noise (BCN) as a function of bias voltage and tilt angle between the direction of the magnetic field and the quantization axis of the HES. In particular, we find transitions from sub-Poissonian (antibunching) to super-Poissonian (bunching) behavior as a direct consequence of the helicity of the edge state electrons. We use the method of full counting statistics within a master equation approach treating the exchange coupling between the spin-1/2 impurity and the HES perturbatively. We express the BCN via coincidence correlation functions of scattering processes between the HES which gives a precise interpretation of the Fano factor in terms of bunching and antibunching behavior of electron jump events. We also investigate the effect of electron-electron interactions in the HES in terms of the Tomonaga-Luttinger liquid theory.

AB - Edge states of two-dimensional topological insulators are helical and single-particle backscattering is prohibited by time-reversal symmetry. In this work, we show that an isotropic exchange coupling of helical edge states (HES) to a spin 1/2 impurity subjected to a magnetic field results in characteristic backscattering current noise (BCN) as a function of bias voltage and tilt angle between the direction of the magnetic field and the quantization axis of the HES. In particular, we find transitions from sub-Poissonian (antibunching) to super-Poissonian (bunching) behavior as a direct consequence of the helicity of the edge state electrons. We use the method of full counting statistics within a master equation approach treating the exchange coupling between the spin-1/2 impurity and the HES perturbatively. We express the BCN via coincidence correlation functions of scattering processes between the HES which gives a precise interpretation of the Fano factor in terms of bunching and antibunching behavior of electron jump events. We also investigate the effect of electron-electron interactions in the HES in terms of the Tomonaga-Luttinger liquid theory.

KW - cond-mat.mes-hall

UR - http://www.scopus.com/inward/record.url?scp=85136170533&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.106.085406

DO - 10.1103/PhysRevB.106.085406

M3 - Article

VL - 106

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 8

M1 - 085406

ER -