Next Seminar 

Chiral nonlocal currents in single layer graphene from orbital valley Hall effects

Tuesday June 21st 2022, 16h – A204

Invited speaker:

Mario Amado

(University of Salamanca)

In this work we report on electrical measurements on single layer graphene Hall-bars encapsulated within hexagonal boron nitride thin films with controlled twisting angle between the layers. The samples have been fabricated by means of a cryo-etching method [1], permitting an unprecedented control of the roughness of the edges. The whole structure was placed onto a thin graphite back gate, preventing dopants or trapped charges arising from the standard semiconductor substrates [2]. 

We have carried out an exhaustive study of the electrical response at different temperatures when an in-to-out-of-plane external magnetic field has been exerted with special attention to the possible effects arising due to the Moiré pattern. Local and non-local signals are presented and a striking chiral behavior at low magnetic fields of the nonlocal currents resulting from a charge carrier-valley coupling is found, in stark contrast with previous results of similar structures at different twisting angles [3]. Orbital valley Hall effect [4,5] has been found responsible for the presented chiral response with thorough theoretical calculations supporting the experimental results [6].

References

[1]    V. Clericò, J. A. Delgado-Notario, M. Saiz-Bretín, A. V. Malyshev, Y. M. Meziani, P. Hidalgo, B. Méndez, M. Amado, F. Domínguez-Adame, and E. Diez, Scientific Reports, 9 (2019) 13572
[2]    A.A. Zibrov, C. Kometter, H. Zhou, E. M. Spanton, T.  Taniguchi, K. Watanabe, M. P. Zaletel and A. F. Young, Nature. 549 (2017) 360
[3]    A. Aharon-Steinberg, A. Marguerite, D. J. Perello, K. Bagani, T. Holder, Y. Myasoedov, L. S. Levitov. A. K. Geim, and E. Zeldoz, Nature 593 (2021) 528
[4]    S. Bhowal and G. Vignale, Physical Review B. 103 (2021) 195309
[5]    S. Roche, S. R. Power, B. K. Nikolić, J. H. García, and A.-P. Jauho, Journal of Physics: Materials 5 (2022) 021001
[6]    J. Salvador-Sánchez et al. arXiv:2206.04565.

Upcoming seminars

September 2022 (TBA)

Past seminars

• Werner Wegscheider (ETH-Zurich)

• Danijela Marcovic (UMR-Thales)

• Mathieu Delbecq (LPENS)

• Jorge Vallejo-Bustamante (LPS)

• Liam Farrar (University of St. Andrews)

• Christophe Mora (Universite de Paris)

• Francois Parmentier (SPEC)

• Herve Aubin (C2N)

• Michael Manfra (Purdue University)

• Banan Kerdi (LNCMI-Toulouse)

• Abhishek Juyal (Neel Institute)

• Arthur Marguerite (College de France)

• Kamran Behnia (ESPCI)

• Pierre Capiod (Debye institute for Nanomaterials)

• Audrey Bienfait (ENS-Lyon)

• Sebastien Toussain (UCL)

• David Goldhaber-Gordon (Stanford)

• Javad Shabani (NYU)

• Olivier Maillet (Aalto)

• Mitali Banerjee (EPFL)

• Anais Dreau (L2C) 

• Klaus Ensslin (ETH- Zurich) 

• Xavier Waintal (CEA- Grenoble) 

• Gwendal Feve (LPENS) 

• Shuoying Yang (MPI-Halle) 

• Yann Gallais (MPQ) 

• Carles Altimiras (CEA - Saclay)

• Alexandra Palacio- Morales ( LPS) 

• Everton Arrighi (Neel Institute)