Już 15 stycznia 2026 roku o godz. 12:30 w Audytorium Aleksandra Jabłońskiego prof. dr hab. Paweł Kowalczyk (Katedra Fizyki Ciała Stałego, Uniwersytet Łódzki) wygłosi wykład pt. "2D Materials: path toward new phenomena".
Streszczenie:
Recently, growing interest in 2D materials is observed initiated by exfoliation of graphene followed by investigations of silicane, germanene and stanene all located in 14th group of periodic table. Elements located in 15th group are also capable to crystalize in 2D form in layered A17 structure (black phosphorus structure, α-form). The widely investigated α-phosphorene is best known example, however, α-arsenene, α-antimonene, α-bismuthene and α-bismuth antimonidene can be synthesized. Interestingly, Sb and Bi can also form stable hexagonal form i.e. β phase based on A7 structure (blue phosphorus). After successive synthesis of these materials we investigated their properties and over years we found number of interesting phenomena including unpinned Dirac states [1], nonsymorphic symmetries leading to formation of Dirac points [2], possible topologically protected edge states [3] and recently superlubicity and signatures of Levy flights in spontanous diffusion of Bi on graphite [4].
The other group of 2D materials is based on transition metal dichalcogenide (TMDC) compounds. From this large group we will focus on TaS2 and WTe2 and their hybrids with graphene. These preliminary research show presence of variety of moire patterns indicating great platform for twistroinics. We will also briefly discuss ageing and laser induced modification of MoTe2, WTe2 and BiTeCl.
Finally, graphene can serve as electrode in many applications. To use it in photovoltaics its work function (WF) has to be substantially increased. We started series of experiments with 2D oxide MoO3 growth [4, 5] which allowed us to tune graphene WF and create first working OLED in Poland.
All these experiments are conducted using surface sensitive techniques including SPM and ARPES. Some of the experiments were conducted with LEEM/PEEM and STXM which are available only at synchrotron facilities.
References
[1] Q. Lu et al., Nat. Comm. 13 (2022) 4603
[2] P.J. Kowalczyk et al., ACS Nano 14 (2020) 1888
[3] S. Salehitaleghani et al., 2D Mat. 10 (2022) 15020
[4] M. Le Ster et al., Small 21 (2025) 2408349
[5] D. Kowalczyk et al., 2D Mat. 8 (2021) 25005
[6] D. Kowalczyk et al., ACS Appl. Mat. Int. 14 (2022) 44506
Organizatorem Kolokwium Czwartkowego jest Instytut Fizyki UMK w Toruniu.