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Ernst Bauer: Improved thermoelectric performance of bulk and thin film full-Heusler systems based on Fe2VAl
Begin: 20.01.2021, 14:10
Location: ZOOM Meeting ID: 958 0426 7376

Volodymyr Buturlim: Uranium in metastable systems: structure, magnetism, superconductivity
Begin: 27.01.2021, 14:10
Location: ZOOM Meeting ID: 958 0426 7376

Lukáš Nádvorník: Terahertz and optical spintronics in ferro- and antiferromagnets
Begin: 24.02.2021, 14:10
Location: ZOOM Meeting ID: 958 0426 7376

 
Title: Denis Kochan: Spin relaxation in graphene-based structures
Number: 39/20
Status: Closing date exceeded
Begin: Thursday, 03.12. 2020, 13:00
Tutor: Karel Carva
Location: ZOOM Meeting ID: 92228188846

Thursday 3 December 2020 at 13:00 in Online webinar

https://cesnet.zoom.us/j/92228188846

Contact K. Carva for the online access information.

 

 Dr. Denis Kochan

Institute for Theoretical Physics University of Regensburg, Germany

Spin relaxation in graphene-based structures

Graphene and other novel 2D materials offer new perspectives for spintronic applications. One important spintronic characteristic to judge the material suitability for such applications is spin relaxation. In graphene the electron spin lifetime is surprisingly short, ranging from 0.1 to 10 ns, depending on the sample quality. Because of small intrinsic spin-orbit coupling the underlying mechanism for the fast spin relaxation had been an outstanding puzzle. We showed that the main culprits are resonant magnetic impurities [1], which can be detected, for example, by sublattice-resolved transport in bilayer graphene  [2]. Despite lacking a band gap, graphene is very versatile for its ability towards functionalization, e.g., by adatoms [3] , or by proximity to two-dimensional transition-metal dichalcogenides (TMDC) [4]. We have recently shown  [5] that graphene on WSe2 exhibits an inverted band structure, which leads to helical edge states in graphene nanoribbons on WSe2, with a bulk spin-orbit gap of about 1 meV, which is giant when compared to 24 micro eV in pristine graphene. Another interesting topic regarding graphene spin relaxation is superconducting coherence, which can naturally disentangle spin-orbit coupling from magnetic moments [6]. In the last part of my talk, I will discuss unique spin relaxation characteristics of graphene proximitized by s-wave superconductors.

References

[1] D. Kochan, M. Gmitra, and J. Fabian, Phys. Rev. Lett. 112, 116602 (2014).
[2] J. Katoch, T. Zhu, D. Kochan, S. Singh, J. Fabian, and R. K. Kawakami, Phys. Rev. Lett. 121, 136801 (2018).
[3] M. Gmitra, D. Kochan, and J. Fabian, Phys. Rev. Lett. 110, 246602 (2013).
[4] M. Gmitra, D. Kochan, P. Högl, and J. Fabian, Phys. Rev. B 93, (2016).
[5] T. Frank, P. Högl, M. Gmitra, D. Kochan, and J. Fabian, Phys. Rev. Lett. 120, 156402 (2018).
[6] D. Kochan, M. Barth, A. Costa, K. Richter, J. Fabian, Phy. Rev. Lett. 125, 087001 (2020)