ABSTRACT

We have seen that the helical edge states in 2DTIs form a Kramers

doublet with the two states being related by the TRS. If a strong

external magnetic field is applied, the TRS is no longer a valid

symmetry. What happens to the helical edge states in that case?

Here we address this question, which is of both theoretical and

practical interest. The answer turns out to be quite counter-intuitive:

the helical edge states can still exist in strong quantizing magnetic

fields. The robustness of the 2DTIs is the consequence of the fact

that the edge states are bound to an effective gap domain wall that

is not destroyed by a magnetic field. However, as we shall see here,

both spectral and transport properties of the helical edge states are

modified by a strong quantizing magnetic field [67, 75, 94].