Accessibility Tools

Past seminars

Seminarium z Magnetyzmu i Nadprzewodnictwa Online

Charge dopants control quantum spin Hall materials

17-05-2023 10:00 - 11:00
Venue
Zoom - Instytut Fizyki PAN
Email
This email address is being protected from spambots. You need JavaScript enabled to view it.
Speaker
prof. dr hab. Tomasz Dietl
Affiliation
International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Warsaw

To view the recording of the talk, please contact Prof. Andrzej Szewczyk: This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Unlike in the quantum Hall effect and quantum anomalous Hall effect, the quantization precision in the quantum spin Hall effect depends on unavoidable background impurities and defects. However, doping with magnetic ions restores the quantization accuracy.

Semiconductors’ sensitivity to electrostatic gating and doping accounts for their widespread use in information communication and new energy technologies. In the talk, I will present outcomes of two companion papers [1,2], inspired by experimental data accumulated in Wuerzburg and Warsaw for HgTe and (Hg,Mn)Te quantum wells and bulk crystals. Results of those papers demonstrate quantitatively and with no adjustable parameters that the presence of paramagnetic acceptor dopants elucidates a variety of hitherto puzzling properties of two-dimensional topological semiconductors at the topological phase transition and in the regime of the quantum spin Hall effect. The concepts of resonant states, charge correlation, Coulomb gap, exchange interaction between conducting electrons and holes localized on acceptors, strong coupling limit of the Kondo effect, the Luttinger correlations, and bound magnetic polaron explain a short topological protection length, high hole mobilities compared with electron mobilities, and different temperature dependence of the spin Hall resistance in HgTe and (Hg,Mn)Te quantum wells. A new concept of precessional dephasing of a carrier spin by a dense bath of localized spins is put forward. It is concluded that while electrostatic gating is widely used to reveal the unique properties of quantum materials, the obtained results demonstrate that charge dopants play an important and unanticipated role in the physics and applications of topological semiconductors.

[1] T. Dietl, "Effects of charge dopants in quantum spin Hall materials", Phys. Rev. Lett. 130, 086202 (2023).

[2] T. Dietl, “Quantitative theory of backscattering in topological HgTe and (Hg,Mn)Te quantum wells: Acceptor states, Kondo effect, precessional dephasing, and bound magnetic polaron", Phys. Rev. B 107, 085421 (2023) [Editors’ Suggestion].

The lecture will be delivered in English.

 
 

List of Dates (Page event details)

  • 17-05-2023 10:00 - 11:00
Save
Cookies user preferences
We use cookies to ensure you to get the best experience on our website. If you decline the use of cookies, this website may not function as expected.
Accept all
Decline all
Read more
Essential
Essential cookies
These cookies are necessary for the correct operation of the website and therefore cannot be disabled on this level; the use of these cookies does not involve the processing of personal data. While you can disable them via your browser settings, doing so may prevent the website from working normally.
Accept
Analytical cookies
These cookies are particularly intended to enable the website administrator to monitor the website traffic statistics, as well as the sources of traffic. Such data is typically collected anonymously.
Google Analytics
Accept
Decline