Monday 12 April 2021, 13:45 CET
Operando observation of reversible oxygen migration and phase transitions in ferroelectric Hf0.5Zr0.5O2 thin films

Speaker: Dr Pavan Nukala, Center for Nanoscience and Engineering, Indian Institute of Science, India
Host: Dr Alexander Björling, scientist at NanoMAX beamline

Keywords: nanoelectronics, atomic resolution electron microscopy, in situ electrical biasing, nanobeam x-ray diffraction

Unconventional ferroelectricity, robust at reduced nanoscale sizes, exhibited by hafnia-based thin-films presents tremendous opportunities in nanoelectronics. However, the exact nature of polarization switching remains controversial. We investigated epitaxial Hf0.5Zr0.5O2 (HZO) capacitors, interfaced with oxygen conducting metals (La0.67Sr0.33MnO3, LSMO) as electrodes, using atomic resolution electron microscopy while in situ electrical biasing and operando nanobeam x-ray diffraction at NanoMAX beamline. In the past, our group has discovered a new structural phase in epitaxial samples of HZO grown using pulsed laser depostion which show increasing polarization with decreasing sizes, all the way upto record values of 35 uc/cm2 (for 6 nm thick film) [1]. We utilize differential phase contrast STEM imaging in conjunction with in situ biasing, and follow directly interpretable oxygen dynamics at an atomic scale, albeit under DC stressing conditions. Through operando XRD measurements, we follow the evolution of the Bragg peaks of HZO (and LSMO) on the 2D detector with 1 ms resolution upon cycling the devices at 100 Hz. These measurements unravel oxygen migration assisted short-term ferroelectric switching dynamics and electromechanical properties of HZO.

[1] P. Nukala et al., Operando observation of reversible oxygen migration and phase transitions, arXiV.2010.10849 (2020)

 

Extraordinary SCIENTÍFika session

Tuesday 30 March 2021, 16:00 CET 

How do intruders take over their hosts?

Speaker: Prof Ada Yonath, Nobel Prize in Chemistry in 2009
Host: Dr. Christine Darve, engineering scientist at European Spallation Source (ESS)

Synchrotron radiation and Cryo EM illuminated the basic life process: the translation of the genetic code. In a still unclear mechanism, the viruses, which lack such systems, take over their hosts machinery for replicating themselves.

Thanks to all who participated to the extraordinary SCIENTÍFika session hosting Nobel Prize laureate in Chemistry in 2009 Prof Ada Yonath on March 30th, we were glad to see such a numerous audience! It was a great honor and pleasure to have the opportunity to hear Prof Yonath´s inspiring experience and chat about open scientific questions!

 

 

Monday 29 March 2021, 13:45 CET
Mass extinctions in Earth´s history through Balder and NanoMax

Speaker: Prof Vivi Vajda, Paleontology Department, Swedish Museum of Natural History, Sweden

Host: Dr Kajsa Sigfridsson Clauss, scientist at Balder beamline

Keywords: fossils, asteroids, vibrational microspectroscopy methods

The composition of fossil leaves  and organelles in fossilised plants from the Jurassic was recently revealed through multiple vibrational microspectroscopy methods (FT-IR, Raman) at MAX IV, showing that these methods can provide information on fossilised organic matter.

Our next project aims to geochemically analyse asteroid impact spherules and sediments formed when the Chicxulub crater was excavated by an asteroid, 66 million years ago causing the extinction of, amongst others, the dinosaurs. The chemical mapping of the spherules contributes with knowledge on the distribution of elements in the silica spherules, providing information on the composition of the Asteroid. We further use XANES spectra of the different relevant elements to detect event beds of different age where extinctions have occurred, aiming at providing clues concerning the triggering mechanisms behind these events – volcanism or asteroids??

 

Monday 22 March 2021, 13:45 CET

Magnetic Materials and Topology

Speaker: Prof Claudia Felser, Max Planck Institute for Chemical Physics of Solids, Germany
Host: Dr. Craig Polley, scientist at BLOCH beamline

Keywords: topology, magnetic materials, angle-resolved photoemission

Topology, a mathematical concept, recently became a hot and truly transdisciplinary topic in condensed matter physics, solid state chemistry and materials science. All 200 000 inorganic materials were recently classified into trivial and topological materials: topological insulators, Dirac, Weyl and nodal-line semimetals, and topological metals [1]. Around 20% of all materials host topological bands. Currently, we have focused also on magnetic materials, a fertile field for new since all crossings in the band structure of ferromagnets are Weyl nodes or nodal lines [2], as for example Co2MnGa and Co3Sn2S2. Beyond a single particle picture and identified antiferromagnetic topological materials [3].

[1] Bradlyn et al., Nature 547  298, (2017), Vergniory, et al., Nature 566 480 (2019).
[2] Belopolski, et al., Science 365, 1278 (2019), Liu, et al. Nature Physics 14, 1125 (2018), Guin, et al. Advanced Materials 31 (2019) 1806622, Liu, et al., Science 365, 1282 (2019), Morali, et al., Science 365, 1286 (2019)
[3] Xu et al. Nature 586 (2020) 702.

 

Monday 15 March 2021, 13:45 CET
Multimodal and Coherent X-ray imaging techniques for thin-film solar cell research

Speaker: Prof Jens Wenzel Andreasen, Department of Energy Conversion and Storage, Technical University of Denmark, Denmark
Host: Dr. Innokenty Kantor, manager at DanMAX beamline

Keywords: thin-film solar cells, X-ray imaging
3rd generation solar cells are often polycrystalline and with a complex chemistry. Common to all thin-film solar cell technologies is the strong correlation between device performance and nano-structure of the photo-active layer, interfaces and electrodes. With a combination of several modalities, X-ray imaging techniques can probe the most important physical properties of such devices, even during operation. We have demonstrated this on samples and working devices of Copper Zinc Tin Sulfide (CZTS) solar cells. The applied techniques include combinations of resonant X-ray ptychographic tomography [1], X-ray Beam Induced Current, scanning X-ray fluorescence and 3D X-ray Diffraction.
[1] Fevola et al. (2020) Phys. Rev. Res. 2, 013378. https://doi.org/10.1103/PhysRevResearch.2.013378

 

Monday 8 March 2021, 13:45 CET
Towards a more affordable solar cell: Molecular scale techniques as a tool to improve long term stability and efficiency on solar absorbing layer nanocrystals

Speaker: Associate Professor Arnaldo Naves de Brito, Applied Physics Department, University of Campinas, Brazil
Host: Dr. Gunnar Öhrwall, scientist at FlexPES beamline

Keywords: lumiscent nanocrystals, solar cells, electron spectroscopy

Highly luminescent Cesium Lead Halide Perovskites Nano-Crystals (CLHP-NCs), CsPbX3 X=Cl,Br,I, are a promising new-comer as solution-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. CLHP-NCs are cheap to produce but still suffer from low colloidal and phase stability. Besides, molecular engineering of its bandgap is crucial for its su
ccess in the clean energy field. In July 2020, we inaugurated electron spectroscopy (ES) on NCs diluted in non-polar liquids.  In this talk, we show how ES can provide valuable information, on a molecular scale, to guide new synthesis strategies for more stable and efficient CLHP-NCs.

 

Monday 1 March 2021, 13:45 CET
Developing materials for the quantum anomalous Hall effect: From extrinsic to intrinsic magnetic topological insulators

Speaker: Prof Oliver Rader, Department Spin and Topology in Quantum Materials, Helmholtz-Zentrum Berlin (BESSY II), Germany
Host: Dr. Evangelos Golias, scientist at MAXPEEM beamline

Keywords: ferromagnetic topological insulators, angle-resolved photoemission
Ferromagnetic topological insulators have been used to demonstrate the quantum anomalous Hall (QAH) effect which may find applications in lossless device interconnects, spintronics, and topological qubits. The materials were Cr and V doped topological insulators, however the QAH effect appeared only for temperatures up to 1 K, much lower than the principle limit given by the Curie temperature of the materials. Another key parameter is the size of the magnetic gap at the Dirac point of the topological surface state which, however, has never been observed directly by spectroscopic means. We use angle-resolved photoemission with and without spin resolution to reveal the magnetic gap in the topological insulators MnBi2Te4/Bi3Te4 and MnSb2Te4. We point out the role of the valency of the magnetic dopant for the structure, what the structure in turn means for the size of the magnetic gap, and shed light on the role of the spin orbit interaction for the gap formation. It is shown that MnSb2Te4 is a topological insulator where the magnetic gap can be followed up to the record-high Curie temperature of 50 K and where disorder plays a surprising role.

 

Monday 22 February 2021, 13:45 CET
The study of GGAG scintillating crystals by means of UV-VUV luminescence excitation spectroscopy

Speaker: Dr Vladimir Pankratov, Institute of Solid State Physics, University of Latvia, Latvia
Host: Dr Antti Kivimäki, manager at FinEstBeAMS beamline

Keywords: scintillators, luminescence, VUV excitation spectroscopy
Scintillator detectors play an irreplaceable role in high-energy physics, spectrometry of low energy γ- quanta, applications in medical imaging, safety systems, space applications, well and mud logging. Among other scintillators cerium doped gallium gadolinium aluminum garnet (Gd3Ga3Al2O12:Ce or GGAG:Ce) nowadays is one of the most relevant scintillator materials. Luminescence properties under UV-VUV excitation reveal the electronic structure of Ce3+ exited states and energy transfer process in the co-doped GGAG:Ce single crystals. The obtained information will be utilized to improve and modify growing technology and enhance the scintillation performance of GGAG single crystals.

 

Monday 15 February 2021, 13:45 CET
High-Resolution Resonant Inelastic Soft X-Ray Scattering on Small Molecules: An Overview of Recent Results and Opportunities at MAX IV

Speaker: Prof Jan-Erik Rubensson, Department of Physics and Astronomy, Molecular and Condensed Matter Physics, Uppsala University, Sweden
Host: Dr Victor Ekholm, scientist at VERITAS beamline

Keywords: resonant inelastic soft X-ray scattering (RIXS), small molecules, ultrafast electronic-vibronic dynamics
Visions for resonant inelastic soft X-ray scattering (RIXS) applied to small molecules will be discussed, and some recent results presented. The importance of dipole selection rules in the investigation of ultrafast electronic-vibronic dynamics will be emphasized. Emerging opportunities at VERITAS, due to the very high energy resolution, the polarization control in both incident and scattered radiation, and the availability of a large range of scattering angles will be discussed.

 

Monday 8 February 2021, 13:45 CET
Serial crystallography as a tool to study protein structure and dynamics

Speaker: Associate Professor Gisela Brändén, Department of Chemistry & Molecular Biology, University of Gothenburg, Sweden
Host: Monika Bjelcic, PhD student at BioMAX beamline

Keywords: serial crystallography, X-ray diffraction, protein structure and dynamics
Serial crystallography is a novel method within macromolecular crystallography that allows determination of protein structures at room temperature and enables time-resolved studies of protein dynamics. The method was first developed at X-ray free electron lasers, but has during the last few years been successfully established also at synchrotron facilities. For serial crystallography to become accessible to more users a number of challenges have to be overcome, especially regarding sample preparation, delivery and reaction triggering. Here, I will describe how we use serial crystallography to study challenging membrane proteins and biological targets of pharmaceutical interest. In await of the dedicated beamline MicroMAX, we have been involved in establishing the method at BioMAX through a series of experiments using various sample delivery setups.

 

Monday 1 February 2021, 13:45 CET
Permanent magnets a challenge of size, shape, and orientation  

Speaker: Associate Professor Mogens Christensen, Department of Chemistry, Aarhus University, Denmark
Host: Dr Mads Ry Jørgensen, manager at DANMAX beamline

Keywords: magnetic materials, textured materials, X-ray and neutron diffraction, instrument development
Magnetic materials are omnipresent in our daily life’s, ranging from electromotors and generators converting between kinetic energy and electricity to hard drive data storage. Magnetism is a quantum mechanical phenomenon related to the number of unpaired electrons on the atomic level. Understanding and controlling structures from the atomic via the nanoscale to the microscopic level allows the design and building of better performing magnetic materials. Synchrotron light is essential for investigating the compaction and alignment of permanent magnetic material on a sub-second time scale. The obtained information will be utilized to improve the processes and enhance the performance of magnetic materials.

Monday 25 January 2021, 13:45 CET
Semiconductor nanostructures for future devices: Studying surface chemistry in-situ

Speaker: Prof Rainer Timm, Department of Physics, Synchrotron Radiation Research, NanoLund, Lund University, Sweden
Host: Dr Andrey Shavorskiy, manager at HIPPIE beamline

Keywords: semiconductor nanostructures, ambient-pressure XPS
Semiconductor nanostructures made of III-V alloys such as InAs are promising for electrical devices with superior performance compared to Si technology. However, the quality of the interface to the semiconductor still limits the progress. Here, I will compare results from different MAX IV spectroscopy and imaging beamlines to investigate the interface between InAs substrates or nanowires and thin oxide or metal layers. The main focus will be placed on ambient-pressure XPS studies performed during the atomic layer deposition of a thin dielectric, which simultaneously removes the unwanted native oxide. By monitoring the surface chemistry during the ongoing reaction, we could reveal new insights in this industrially relevant process.

 

Monday 18 January 2021, 13:45 CET
Time resolved SAXS studies of nanocube assembly in levitating drops

Speaker: Prof Lennart Bergström, Department of Materials and Environmental Chemistry, Stockholm University, Sweden
Host: Dr Tomás Plivelic, manager at CoSAXS beamline

Keywords: Nanoparticle assembly, Time-resolved small angle X-ray scattering (SAXS)
Nanoparticle assembly is a promising route to produce mesostructured materials with unique properties. Probing the dynamics of assembling nanoparticles in liquids is challenging and requires not only methods with suitable spatial- and time-resolution, but also careful design of measurement environments. Here, recent work on time-resolved techniques have been used to probe nanocube assembly in levitating drops. Time-resolved small angle X-ray scattering (SAXS) combined with electron microscopy and interparticle potential calculations showed that the evaporation-induced mesocrystallization process proceeds in two stages involving the formation and rapid transformation of a dense, structurally disordered phase into ordered mesocrystals (1). It will be demonstrated how evaporation-driven poor-solvent enrichment allows for the assembly of large particle assemblies, which display a higher crystalline quality compared to the classical single solvent approach (2). Evaporation-induced assembly in weak magnetic fields was found to proceed in two stages where assembly of micron-sized mesocrystals with a cubic shape preceded the formation of fibers with a high degree of crystallographic coherence and tunable diameters (3). We will discuss how the transition from 3D growth of the primary mesocrystals to the second stage 1D assembly of the elongated fibers was related to the size and field dependence of isotropic van der Waals and directional dipolar interactions between the interacting mesocrystals.
1.M Agthe, T S. Plivelic, A Labrador, L Bergström, G Salazar-Alvarez, Nano Lett., 16, 6838-6843 (2016)
2. Z-P Lv, M Kapuscinski, L Bergström, Nature Comm., 10, 4228 (2019)
3. M Kapuscinski, P Munier, M Segad, L Bergström, Nano Lett., 20, 10, 7359–7366 (2020)

 

Monday, 14 December 2020 at 13:45 CET
Electronically driven spin-reorientation transition of the correlated polar metal Ca3Ru2O7

Speaker: Prof Philip King, School of Physics and Astronomy, University of St. Andrews, UK
Host: Dr. Craig Polley, scientist at the BLOCH beamline

Keywords: spin-orbit coupling in solids, angle-resolved photoemission spectroscopy
The influence of spin-orbit coupling in solids has become the subject of much attention in recent years. When combined with a breaking of inversion symmetry, it can lift the spin degeneracy of electronic states via the so-called Rashba effect, with potential applications in spin-generation and manipulation, spin-transfer torques, and the formation of topological states.1 Here, using angle-resolved photoemission spectroscopy, I will demonstrate how Rashba-type spin-orbit interactions mediate a dramatic reconstruction of the Fermi surface accompanying at a spin-reorientation phase transition in the correlated polar metal Ca3Ru2O7,2 pointing to a new form of magneto-electronic coupling, and highlighting the delicate balance between symmetry-breaking, electronic correlations, and spin-orbit coupling in solids.
Manchon et al., Nature Materials 14 (2015) 871
Marković et al., PNAS 117 (2020) 15524