New emergent phases at the interface of 2D materials
- Date
- Thursday 24 October 2024
- Time
- Address
-
Gorlaeus Building
Einsteinweg 55
2333 CC Leiden - Room
- BM.1.23
Dirac fermions to excitonic insulators—2D materials host a range of exotic states as a result of quantum confinement. Due to the very nature of 2D materials, these states appear at the surface, making them susceptible to external disturbances from their immediate surroundings. Deliberate manipulation of such interactions can give rise to novel emergent states and lead to novel functional devices. We aim to study surfaces and interfaces of 2D materials by
external perturbations such as electric field and pressure.
In the first part of the talk, I will demonstrate a large-area passivation layer for graphene, a single layer of Carbon, by mechanical transfer of ultrathin Ga2O3 synthesized on the surface of liquid Ga metal [1]. Electrical measurements of millimeter-scale passivated and bare CVD graphene on SiO2 substrate indicate that the passivated graphene maintains its high field effect mobility, desirable for applications. Surprisingly, the temperature-dependent resistivity is reduced in our passivated graphene over a range of temperatures below 230 K, due to the interplay of screening of the remote optical phonon modes of SiO2 by the high dielectric constant of Ga2O3, and the relatively high characteristic phonon frequencies of Ga2O3. Raman spectroscopy and electrical measurements indicate that Ga2O3 passivation also protects graphene from further processing such as plasma-enhanced atomic layer deposition of Al2O3.
It is well-known that when a 2D magnetic material is proximitized with a 2D non-magnetic material, a magnetic proximity effect is induced through the interface which can often lead to new quantum states. We are interested in understanding the physical mechanism responsible for this effect and how it can be strengthened. In the second part of the talk, I will talk about briefly touch upon our ongoing efforts at Leiden university on this topic.
References
- M. Gebert, S. Bhattacharyya et al., Nano Lett., 23, 363 (2023).
- [2] S. Islam, S. Bhattacharyya, et al. Phys. Rev. B, 97, 241412 (2018).
- [3] S. Bhattacharyya et al. 33, 2007795 (2021)