Ultrafast physics and beyond Severo Ochoa Workshop

In this workshop we will discuss some of the latest trends in ultrafast physics and reach out to other communities, including chemists and biologists, and show what ultrafast measurements can do for you. Topics include ultrafast dynamics in liquids, biological matter, oxides, spintronic systems, phonons, heat, 2D materials and organic semiconductors.

Monday 30 May 2022
From 10AM to 5:30PM (CET)
ICN2 Seminar Room and Online
Register here and choose your attendance modality (in person / online)

The workshop is part of the series organised within the framework of the Spanish Excelencia Severo Ochoa Programme.

Prof. Mischa Bonn

Mischa Bonn, Max Planck Director at the Max Planck Institute for Polymer Research, in Mainz, Germany studied Physical Chemistry at University of Amsterdam. He received his PhD from the FOM-Institute for Atomic and Molecular Physics, as well in Amsterdam. In 1997 he became Humboldt and European Fellow at the Fritz Haber Institut der Max Planck Gesellschaft, Berlin, in the groups of G. Ertl and M. Wolf. 1998 he joined as visiting scientists the group of Heinz at the Columbia University NY, USA.

In 1999 he was appointed as assistant professor at the Leiden Institute of Chemistry and promoted to associate professor with tenure in 2002. From 2003 to 2013 he worked as Group Leader at the FOM-Institute for Atomic and Molecular Physics. In 2011 he joined the Max Planck Institute for Polymer Research, where he is currently in charge as managing director. In parallel he became also honorary professor at the Johannes Gutenberg University of Mainz. Additionally, he still serves as an extraordinary Professor awarded to him in 2005 from the Physics Departement of the University of Amsterdam. His research areas focus on label-free (ultrafast) vibrational spectroscopy and microscopy of biomolecular systems and water in such systems, including model systems for biological membranes. Further interest is centered around studies of carrier dynamics in photovoltaic building blocks. He is author of almost 250 peer reviewed papers in highly ranked journals. For his research he received numerous prizes and fellowships such as the Gold Medal from the Royal Dutch Chemical Society (2009), personal Fellowship (’VICI’) from the Netherlands Scientific Organization (NWO) for research, elected Member of ‘The Young Academy’ of the ’Royal Dutch Academy of Arts and Sciences’ (KNAW), Amsterdam and a personal fellowship from the Japanese Society for the Promotion of Sciences (JSPS);

Prof. Andrea Caviglia

Andrea Caviglia is a Professor at the Department of Quantum Matter Physics, University of Geneva, Switzerland, where he leads the Laboratory for Designer Quantum Materials. His research is devoted to the understanding and control of fundamental new properties of matter arising from quantum principles. His laboratory combines atomic scale synthesis of quantum materials with advanced light sources to engineer material properties in and out of equilibrium. These experimental innovations have enabled a number of discoveries in the field of quantum material control including light-induced coherent spin-waves transport in antiferromagnets, light control of magnetic order and ultrafast strain engineering in correlated oxides. He has also contributed to the unveiling of emergent phenomena in quantum materials engineered at the atomic scale, including electronic and topological reconstructions, spin-orbital quantum states, quantum oscillations and superconductivity at oxide interfaces.

Prof. Giulio Cerullo

Giulio Cerullo is a Full Professor with the Physics Department, Politecnico di Milano, where he leads the Ultrafast Optical Spectroscopy laboratory. Prof. Cerullo’s research activity covers a broad area known as “Ultrafast Optical Science”, and concerns on the one hand pushing our capabilities to generate and manipulate ultrashort light pulses, and on the other hand using such pulses to capture the dynamics of ultrafast events in molecular and solid-state systems. He has published over 450 papers which have received >25000 citations (H-index: 80). He is a Fellow of the Optical Society of America and of the European Physical Society and Chair of the Quantum Electronics and Optics Division of the European Physical Society. He is the recipient of an ERC Advanced Grant (2012-2017) on two-dimensional electronic spectroscopy of biomolecules. He has been General Chair of the conferences CLEO/Europe 2017, Ultrafast Phenomena 2018 and the International Conference on Raman Spectroscopy 2020.

Prof. C. Ciccarelli

Chiara Ciccarelli is a Lecturer at the Cavendish Laboratory in Cambridge. She received her PhD from Cambridge in 2012 and from 2012 to 2016 held a Junior Research Fellowship at Gonville and Caius College (Cambridge). She is a Royal Society University Research Fellow since October 2017. Her research focusses on the study of spin-charge conversion effects in inversion-asymmetric magnetic structures and at superconductor-ferromagnet interfaces. More recently she moved part of her research to ultra-fast spintronics. She has given more than 30 invited talks at international conferences in the past five years and she is participating to different international networks including a European COST action and an Innovative Training Network on the theme of ultra-fast magnetism.

Prof. Tobias Kampfrath

Professor (W3) of Experimental Physics at Freie Universität Berlin

Research topics: Study and control of ultrafast processes in complex solids, e.g., terahertz dynamics and terahertz transport of electrons and spins in nanostructures and at interfaces; Nonlinear terahertz spectroscopy of solvents; Terahertz radiation: generation, steering, interaction with tailored matter.

Prof. Akshay Rao

Akshay received his undergraduate degree from St Stephen’s College, University of Delhi in 2006 and his MSc from the University of Sheffield in 2007. He received his PhD from the University of Cambridge in 2011, working in the group of Prof. Sir Richard Friend, following which he held a Junior Research Fellowship at Cambridge.

In October 2014 he started his independent research group in Cambridge suppored by an EPSRC Early Career Fellowship and Winton Advanced Research Fellowship. He currently holds the Harding Assistant Professorship at the Cavendish Laboratory in Cambridge. His research group is interested in the optical and electronic properties of next generation energy materials and studies these materials with novel optical spectroscopies and microscopies, as well as using the insights gained to develop new materials and device concepts. Akshay is also co-founder of two startups, Cambridge Photon Technology and Cambridge VisIon.

Dr Aswathi K. Sivan

Aswathi K. Sivan received her diploma in Physics from the University of Mumbai in 2017. From 2012 to 2017, she was an Innovation in Science Pursuit for Inspired Research(INSPIRE) fellow. In 2021, she received her doctorate in Physics from the Università di Roma "Sapienza" with summa cum laude. During her Ph.D., she studied the ultrafast carrier dynamics in nanowires of different semiconducting materials. She is an expert in femtosecond transient absorption spectroscopy of nanostructures. Currently, she is a postdoc at the Nanophononics group of Prof. Ilaria Zardo at the University of Basel, Switzerland. Her research interests include carrier-phonon interactions and lattice dynamics of low-dimensional structures.

Prof. Mischa Bonn

Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

Charge transfer and mobility in novel (hybrid) materials

Many electro-optic devices, including solar cells, light-emitting diodes and photocatalysts rely on the interconversion of light and charges. Following their optical or electrical injection, the behavior of these charges determines the device efficiency. Key aspects of charge carrier dynamics are charge separation, charge mobility, and charge transfer across interfaces in hybrid systems. In my presentation, I will demonstrate how contact-free terahertz photoconductivity measurements can provide important insights into charge transfer and mobility in novel (hybrid) materials, including 2D materials, MXenes, and perovskites.

Prof. Andrea Caviglia

Department of Quantum Matter Physics, University of Geneva, Switzerland

Controlling interfaces of quantum materials with light

Exerting control over quantum materials is one of the main goals in condensed matter physics. Oxide interfaces have emerged as a versatile platform for material design, where new fundamental properties can be generated by assembling condensed matter at the atomic scale. Light plays a pivotal role in this scientific exploration. Probing materials with light reveals the collective excitations and the energy landscapes that underpin correlated dynamics. Recently we have come to the realisation that light not only reveals the organisation of condensed matter, it can also unlock new properties and promote phase transitions. The overarching goal of the field is to control macroscopic material properties, paving the way to new scientific insights and future emerging technologies. We will discuss two examples of material design at oxide interfaces and surfaces, focusing on the control of magnetic order and transport of angular momentum. In the first example, we will consider the control of magnetic ordered states using light. We will show that light-driven phonons can be utilized to coherently manipulate macroscopic magnetic states. Intense mid-infrared electric field pulses, tuned to resonance with a phonon mode of the antiferromagnet DyFeO3, induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. In the second example we will discuss the emission and detection of a nanometre-scale wavepacket of coherent propagating magnons in the antiferromagnetic oxide dysprosium orthoferrite using ultrashort pulses of light.

Prof. Giulio Cerullo

Dipartimento di Fisica, Politecnico di Milano, Italy

Real-time observation of conical intersection in biomolecules

Conical intersections (CIs) are regions of the potential energy landscape of a molecule where the electronic and nuclear degrees of freedom become strongly mixed and the Born–Oppenheimer approximation breaks down. CIs are ubiquitous features in the photophysics and photochemistry of molecules and can be considered as “doorways” through which the photoexcited wavepacket is efficiently funneled to a lower-energy electronic state. CIs play a dual role in the interaction of biomolecules with light: either to promote efficient conversion from a reactant to a product state in a photochemical reaction or to enable efficient dissipation of excess electronic energy, preventing a potentially harmful photochemical reaction. An example of the first case are visual opsin proteins, in which the photoexcited retinal chromophore exploits a CI to promote ultrafast photoisomerization to a ground-state photoproduct which triggers visual transduction. An example of the second case are nucleobases, the building blocks of DNA, for which CIs are used to promote rapid dissipation of excited state energy, preventing photoreactions which could damage the genetic code.

Given the extreme speed of the processes leading to CIs, ultrafast optical spectroscopy is the elective tool for their observation. However, the direct visualization of a wavepacket passing through a CI is challenging, because the energy gap between the interacting levels changes very rapidly over a short time, calling for the combination of high temporal and spectral resolution. In this talk I will present examples of real-time visualization of CIs in biomolecules (opsin proteins and nucleobases) using a specially developed ultrafast transient absorption spectroscopy system combining sub-20-fs time resolution with broad frequency tunability, from the UV to the infrared. I will also discuss the potential of X-ray FELs to open new spectroscopic windows for the detailed study of the CI dynamics, via either element-specific probing or ultrafast structural dynamics.

Prof. C. Ciccarelli

Cavendish Laboratoryn, Cambridge University, UK

Picosecond Spin Seebeck effect in ferromagnets and antiferromagnets

The longitudinal spin Seebeck effect describes the transfer of a spin current from a magnetic insulator driven by a temperature gradient. Here we present our recent studies on the longitudinal spin Seebeck effect on the picosecond timescale in both ferromagnets and antiferromagnets using THz emission spectroscopy. As a function of temperature, we observed a different temperature dependence compared to DC electrical studies carried out in the same temperature range. By comparing different antiferromagnets belonging to the same family of fluoride perovskites we are able to correlate the spin transfer efficiency with the bands of the magnon spectrum.

Prof. Tobias Kampfrath

Freie Universität Berlin and Fritz Haber Institute of the Max Planck Society

Terahertz emission spectroscopy: insights into spin and charge transport and applications

Photocurrents are ubiquitous in physical systems, e.g., in photovoltaics, thermoelectric materials and light harvesting complexes. To study the formation and relaxation of photocurrents on their natural, i.e., femtosecond, time scales, terahertz emission spectroscopy (TES) is a powerful tool: A femtosecond laser pulse launches a photocurrent, which leads to the emission of a terahertz electromagnetic pulse, whose transient electric field is measured. This talk is supposed to show that TES provides new insights into spintronic thin film structures. Examples include ultrafast spin precession, spin transport, spin to charge conversion and the important role of interfaces. Interesting photonic applications such as the generation of ultrashort terahertz electromagnetic pulses also emerge.

Prof. Akshay Rao

Cavendish Laboratory, Cambridge University

Ultrafast Spectroscopy and Microscopy for Energy Materials

The pressing need to shift to a sustainable and zero-carbon economy has brought into focus the need to remake the worlds energy economy within the next 20-30 years. To achieve this, we need a new generation of materials for the generation, storage, transmission and the efficient use of energy. Unlike crystalline materials, such as Si, which have driven the ICT revolution of the past decades, these new energy materials often possess complex nanoscale structures, chemical, structural and energetic disorder, as well as dynamic interfaces. To unlock the transformational potential of these materials calls for new methodologies to elucidate the dynamics of excitations and transport processes on their native time and length scales. In this talk, I will discuss our recent work to develop time-resolved absorption and scattering microscopy platforms to probe these materials. This now allows us to track species such as charges, excitons and also ions and phonons with a spatial precision below 10nm and with time-resolution below 10fs. I will discuss how this is beginning to open a new window into understanding novel semiconductor materials, photocatalytic systems, thermoelectrics and battery electrodes.

Dr Aswathi K. Sivan

Department of Physics - University of Basel

Investigating phonons and thermal transport by pump-probe spectroscopy

The recently growing research field called “Nanophononics” deals with the investigation and control of vibrations in solids at the nanoscale. Phonon engineering leads to a controlled modification of phonon dispersion, phonon interactions, and transport. However, engineering and probing phonons and phonon transport at the nanoscale is a non-trivial problem.

In this talk, we discuss a versatile pump-probe setup we have recently designed and built. This advanced laser system can be coupled to a triple spectrometer equipped with an electron-multiplying charged-coupled device (EMCCD) or to a photodiode and lock-in amplifier which will enable us to perform pump-probe spectroscopy to study phonon dynamics. The set-up is built in such a way that we can perform:

i. time-resolved spontaneous/stimulated Raman spectroscopy;
ii. (time-resolved) coherent anti-Stokes Raman spectroscopy;
iii. thermal reflectivity measurements;
iv. spatially-resolved pump-probe spectroscopy for determination of phonon mean free path and phonon coherence lengths.


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