Main research directions
2D matters
collaborative projects across academy and industry in the UK and internationally
Unique cleanrooms facilities at the National Graphene Institute enable innovative research
heterostructure devices for transport measurements
device for graphene-water interaction measurements
light-matter interactions:
s-SNOM images of different graphite stacking domains
near-field image of an hBN flake on top a gold crystal exhibitinh hyperbolic phonon polaritons
Some relevant refs:
Y. Yang, J. Li, J. Yin, S. Xu, C. Mullan, T. Taniguchi, K. Watanabe, A.K. Geim, K.S. Novoselov, A. Mishchenko, In situ manipulation of van der Waals heterostructures for twistronics, Science Advances, 6:eabd3655, 2020.
Y. Yang, Y.-C. Zou, C.R. Woods, Y. Shi, J. Yin, S. Xu, S. Ozdemir, T. Taniguchi, K. Watanabe, A.K. Geim, K.S. Novoselov, S.J. Haigh, A. Mishchenko, Stacking Order in Graphite Films Controlled by van der Waals Technology, Nano Letters, 19, 8526, 2019.
Artificial intelligence-assisted materials discovery
Millions of computational materials harboring unique physics and properties await exploration at open science data centers. Future materials science is set to be revolutionized by AI and digital data driven approaches. We aim to leverage AI algorithms, such as variational autoencoders, graph neural networks, and interpretable learning, to autonomously discover materials.
Some relevant refs:
HK Pentz, T Warford, I Timokhin, Q Yang, A Bhattacharya, A Mishchenko. Elf autoencoder: unsupervised exploration of flat-band materials using electronic band structure fingerprints. arXiv preprint arXiv:2406.11967, 2024.
A Bhattacharya, I Timokhin, R Chatterjee, Q Yang, A Mishchenko. Deep learning approach to genome of two-dimensional materials with flat electronic bands, npj Computational Materials 9 (1), 101, 2023.
Quantum transport
Transport in double-gated graphite devices
Van der Waals technology and a better theoretical understanding (from graphene physics) allowed us to unravel interesting physics even in such an old material as graphite
Twistronics in 3D (graphite)
Aligning graphite with hBN results in topological Lifshitz transitions, Brown-Zak quantum oscillations, and Hofstadter butterfly
ABC (Rhombohedral) graphite: probably the simplest topological insulator with gapped bulk and conducting surfaces! It shows clear signatures of strong electronic correlations – no need for moiré!
Correlations in rhombohedral graphite
Some relevant refs:
C. Mullan, S. Slizovskiy, J. Yin, Z. Wang, Q. Yang, S. Xu, Y. Yang, B.A. Piot, S. Hu, T. Taniguchi, K. Watanabe, K.S. Novoselov, A.K. Geim, V.I. Fal'ko, A. Mishchenko, Mixing of moiré-surface and bulk states in graphite, Nature, 620:756, 2023
Y. Shi, S. Xu, Y. Yang, S. Slizovskiy, S.V. Morozov, S.-K. Son, S. Ozdemir, C. Mullan, J. Barrier, J. Yin, A.I. Berdyugin, B.A. Piot, T. Taniguchi, K. Watanabe, V.I. Fal'ko, K.S. Novoselov, A.K. Geim, A. Mishchenko, Electronic phase separation in multilayer rhombohedral graphite, Nature, 584:210, 2020
J. Yin, S. Slizovskiy, Y. Cao, S. Hu, Y. Yang, I. Lobanova, B.A. Piot, S.-K. Son, S. Ozdemir, T. Taniguchi, K. Watanabe, K.S. Novoselov, F. Guinea, A.K. Geim, V. Fal’ko, A. Mishchenko, Dimensional reduction, quantum Hall effect and layer parity in graphite films, Nature Physics, 15, 437, 2019
J.R. Wallbank, D.Ghazaryan, A. Misra, Y. Cao, J.S. Tu, B.A. Piot, M. Potemski, S. Pezzini, S. Wiedmann, U. Zeitler, T.L.M. Lane, S.V. Morozov, M.T. Greenaway, L. Eaves, A.K. Geim, V.I. Fal'ko, K.S. Novoselov, A. Mishchenko, Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures, Science, 353:575, 2016
G.L. Yu, R.V. Gorbachev, J.S. Tu, A.V. Kretinin, Y. Cao, R. Jalil, F. Withers, L.A. Ponomarenko, B.A. Piot, M. Potemski, D.C. Elias, X. Chen, K.Watanabe, T. Taniguchi, I.V. Grigorieva, K.S. Novoselov, V.I. Falko, A.K. Geim, A. Mishchenko, Hierarchy of Hofstadter states and replica quantum Hall ferromagnetism in graphene superlattices, Nature Physics, 10:525, 2014
Nanoconfined water and nanofluidics
2D nanocapillaries enabled by van der Waals technology
Isolated two-dimensional (2D) crystals can be assembled into designer structures layer-by-atomic-layer in a precisely chosen sequence. Using van der Waals (vdW) vdW technology, we have reported the creation of two-dimensional nanocapillary. It can be viewed as if individual atomic planes were pulled out of a bulk crystal leaving an atomically thin void behind (see figure). This technology offers the smallest possible empty spaces that can vary from just a few angstroms in height up to many nanometers on demand.
We will be exploring the nanoconfinement effects based on such nanocapillaries system.
Fabricated on a silicon-based substrate, these nanochannels are fully compatible with microfabrication technology, guaranteeing facile integration with different auxiliary units, such as electrochemical cells, microfluidics, spectroscopy, and electronics.
Such a system thus presents as a versatile platform to systematically explore both the static (structures and interactions) and dynamic (nanofluidics) behaviors of various molecules under extreme confinement.
A range of research activities regarding mass transport at the nanoscale:
-- properties of nanoconfined water
-- graphene-liquid interface (energy harvesting)
-- ionic transport
-- gas selectivity
Aimed at osmotic energy harvesting
Some relevant refs:
Q Yang, Exploring the Nanoconfinement Effect Using 2D Capillaries, Accounts of Materials Research, 4, 1-3 (2023).
P Robin, M Lizée, Q Yang, T Emmerich, A Siria, L Bocquet. Disentangling 1/f noise from confined ion dynamics. Faraday Discuss,246, 556-575 (2023)
ZH Zhou, YT Tan, Q Yang, A Bera, ZC Xiong, M Yagmurcukardes, M Kim, YC Zou, GH Wang, A Mishchenko, I Timokhin, CB Wang, H Wang, CY Yang, YZ Lu, R Boya, HG Liao, S Haigh, HB Liu, FM Peeters, YL Li, AK Geim, S Hu. Gas permeation through graphdiyne-based nanoporous membranes. Nature Communications 13, 1-6 (2022).
Q Yang, P Sun, L Fumagalli, YV Stebunov, SJ Haigh, ZW Zhou, IV Grigorieva, FC Wang, AK Geim. Capillary condensation under atomic-scale confinement. Nature 588, 250-253 (2020).
P Sun, Q Yang, W Kuang, YV Stebunov, W Xiong, J Yu, RR Nair, MI Katsnelson, S Yuan, IV Grigorieva, M Lozada-Hidalgo, FC Wang, AK Geim, Limits on gas impermeability of graphene. Nature 579, 229-232 (2020).
Q Yang, Y Su, C Chi, CT Cherian, K Huang, VG Kravets, FC Wang, JC Zhang, A Pratt, AN Grigorenko, F Guinea, AK Geim, RR Nair, Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation. Nature Materials 16, 1198-1202 (2017).
Novel van der Waals materials growth
Our combined machine learning capability with 2D materials growth technique lead to novel material discovery. We produce high quality crystals for academic research, internally and internationally.