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Microscopy Group

Welcome to the Warwick Microscopy Group
HAADF-STEM image of monolayer NbxW(1-x)S2
Field Mapping of SrTiO3
ADF-STEM image of defects in III-V nanowires
Operando liquid-cell electrochemical TEM imaging of lithium metal dissolution in a modified Li-ion electrolyte. DOI: 10.1002/aenm.202003118.
ABF-STEM image of PbTiO3
HDR Diffraction
D-LACBED pattern from Si
Tilt series of SAED patterns from Si
Using FIB to attach a sample lamella to an in-situ MEMS chip
Welcome to the Warwick Microscopy Research Group homepage. The research interests of the microscopy group members covers a wide range of material systems and microscopy techniques. We have extensive experience in structural characterisation of materials on atomic to nano lengthscales. We make use of a comprehensive suite of microscopes that are maintained by the Microscopy RTP. To find out more about our research, click on the links below to see our group members and publications.

🔬 Funded PhD Studentships available for October 2022 start! 🔬

There are 4 funded PhD Studentships currently available in the microscopy group for October 2022 start. Projects available are listed below. Click on project titles for more information. Click on supervisor names to find out more about their work.
Fast data processing for 4D-STEM
Visualization of electric fields using electron scattering
Understanding 2D material memristors by atomic resolution imaging
High-Resolution Probing Ferroic-ordering by Cryogenic Electron Ptychography

Microscopy Group Research Nuggets

Ferroelectric incommensurate spin crystals

Ferroics can form complex topological spin structures when subjected to particular physical boundaries. A domain structure in a PbTiO3 layer between SrRuO3 electrodes has been discovered with two orthogonal periodic modulations that form an incommensurate polar crystal, and provides a ferroelectric analogue to recently discovered incommensurate spin crystals in ferromagnetic materials. Click the image to find out more.

Interlayer Umklapp hybridisation of bands in 2D heterostructures

Interlayer effects within 2D heterostructures can be studied using spatially-resolved angle-resolved photoemission spectroscopy (microARPES). We show how twist-controlled Umklapp scattering of hybridised electronic states can be used to engineer discrete positions of strong coupling between two 2D materials. Click the image to find out more.

Current-Density-Dependent Electroplating in Ca Electrolytes

Calcium-ion rechargeable batteries are promising emerging candidates for beyond lithium-ion, in part due to the better stability of calcium metal. To exploit this advantage we need to better understand how new calcium electrolytes perform, and particularly the conditions under which dangerous metal dendrites may form. We use operando electrochemical TEM, effectively a micro-battery operated inside the microscope, to image dendrite formation in real-time. Click the video to find out more.

Direct observation and catalytic role of mediator atom in 2D materials

Atomic defects govern material behaviour, most clearly seen with the case of dislocation migration and plasticity. It is understood that defect changes occur via sequential atomic bond rotations; however, modelling tells us the energy barrier for these are high. By combining monochromated aberration corrected TEM imaging of graphene - resolving individual carbon atoms - with TBMD and DFT modelling, we reveal the role of surface adatoms in mediating lower energy defect migration mechanisms. Click the image to find out more.

AI-enabled Cryogenic Electron Ptychography For Bio-macromolecule Imaging

Nobel Prize winning technique, cryogenic electron microscopy (cryo-EM) is a powerful method for visualizing a wide range of biological macromolecules in three dimensions at near-atomic resolution, which can provide direct insights into function and mechanism. Here, we are developing a completely new computational microscopy so called cryogenic electron ptychography, further enhanced by artificial intelligence (AI) and machine learning techniques to recover high fidelity amplitude and phase contrast images of biological macromolecules with state-of-the-art ultrafast detectors at low dose. Click the image to find out more.

Development of in situ Multi-channel 5D STEM Imaging for Functional Materials

Unlike conventional imaging modes, we are developing novel computational diffractive imaging techniques (ptychography, 4D STEM) at a cryogenic temperature together with “big data” processing methods and exploiting opportunities by accelerating its application in functional materials ranging from battery to quantum materials. Furthermore, we are looking at dynamic behaviours of materials in situ and study how they respond to a changing external stimulus (such as electric, magnetic field, temperature and light) at timescales required. Click the image to find out more.

Visualizing electrostatic gating effects in 2D heterostructures

The ability to directly monitor the states of electrons in modern field-effect devices could transform our understanding of the physics and function of a device. We show that micrometre-scale, angle-resolved photoemission spectroscopy (microARPES) applied to two-dimensional van der Waals heterostructures affords this ability, visualizing field-dependent band structure with in-operando measurements. Both optical spectroscopy and microARPES can be carried out on a single device, allowing definitive studies of the relationship between gate-controlled electronic and optical properties. Click the image to find out more.

Revealing Defect Dynamics in III-V Nanowires

For functional applications in next generation technology, semiconductor nanowires should be free of defects that can be detrimental to device performance. Defects in self-catalysed nanowires, produced with sub-optimal growth conditions, have been analysed to identify defect types. In-situ microscopy has been utilised to probe defect dynamics and helps us to understand how to improve nanowire quality. Click the image to find out more.

D-LACBED: Digital Large Angle Convergent Beam Electron Diffraction

By combining lots of individual CBED patterns acquired using computer control of beam tilt, LACBED patterns can be reconstructed. The LACBED patterns provide a wealth of information about sample symmetry and can even be used to solve crystal structure. Click the image to find out more.