ELFT HÍRADÓ

[Kormányos Andor <andor.kormanyos AT ttk.elte.hu>]

ELTE TTK Fizikai Intézet / ELTE Institute of Physics


ORTVAY KOLLOKVIUM / ORTVAY COLLOQUIUM
(https://physics.elte.hu/ortvayseminar)


Thursday, 21st March  2024, 15:00h.

Pócza Jenő Classroom,  Physics Building 1.71

Pázmány Péter sétány 1/A, 1117 Budapest.


Péter Makk
Budapest University of Technology and Economics

Building and Tuning of van der Waals heterostructures

Graphene is the wonder material: it is strong, it has ultra-high mobility, 
and it has a special band structure, which makes it interesting for 
fundamental research. The properties of graphene can also be engineered by 
combining it with other 2D materials using van der Waals stacking – like 
putting bricks of LEGO on top of each other [1]. There are quite many 
building blocks available now: semiconductors, superconductor, magnetic and 
materials with larger spin-orbit interaction. The combination of these can 
lead to novel phases from gate tunable magnets to topological 
superconductors. Moreover, one can also go beyond, what can be done in LEGO: 
these materials can be placed on top of each other under any rotation angle – 
therefore this field is called twistronics [2]. For special, “magic” rotation 
angles novel correlated and topological phases formed. Since in these 
structures the layer distance strongly affects the interaction between the 
layers, pressure is an ideal tool to engineer the band structure of van der 
Waals materials.

In this talk I will show how the bandstructure of van der Waals materials can 
be engineered by placing different 2D materials on top of each other, by 
twisting them or by using pressure [3-6]. Using electrical transport 
measurements, I will show that a spin orbit coupling in graphene can be 
generated by placing another material next by, and also demonstrate how the 
magnetic state of 2D magnets can be tuned using pressure.

[1] K. S. Novoselov et al., Science 353, 6298 (2016).
[2] Nature Physics, 16, 725 (2020).
[3] B. Fülöp et al., Journal of Appl. Phys., 130, 064303 (2021).
[4] B. Fülöp, A. Márffy, S. Zihlmann, M. Gmitra, E. Tóvári, B. Szentpéteri, 
M. Kedves, K. Watanabe, T. Taniguchi, J. Fabian, C. Schönenberger, P. Makk, 
Sz. Csonka, npj 2D Materials and Applications 5, 82 (2021).
[5] M. Kedves et al., Nano Letters, 10.1021/acs.nanolett.3c03029 (2021).
[6] B. Szentpéteri, P. Rickhaus, F. K. de Vries, A. Márffy, B. Fülöp, E. 
Tóvári, K. Watanabe, T. Taniguchi, A. Kormányos, Sz. Csonka, and P. Makk, 
Nano Letters, 21, 8777 (2021).



Andor Kormányos
coordinator