An energy-resolution record for resonant inelastic x-ray scattering

Resonant inelastic x-ray scattering (RIXS) is a powerful technique for studying electronic excitations in a wide variety of new and complex materials, offering momentum- and energy-resolution and potentially even analysis of scattered polarization. Since its inception in the 1990s, the development of RIXS instrumentation and scientific subjects have benefited from a closely intertwined evolution; improvements in energy resolution and throughput, spurred by specific scientific cases, have in turn made new subjects of study feasible. In the continued quest for substantially improved energy resolution, a novel prototype RIXS flat-crystal spectrometer was recently tested at X-ray Science Division beamline 27-ID-B at the U.S. Department of Energy’s Advanced Photon Source (APS). The spectrometer established a new record resolution for RIXS below 10 meV, together with a promise to do even better soon.

Early RIXS work was aimed at the study of charge transfer excitations in transition metal oxides (TMO), including the high-Tc superconducting Cuprates, where electronic excitations could be observed at a few eV. As the understanding of strongly correlated electron systems progressed, orbital degrees of freedom came into focus: in many Mott insulators, transitions between the active d-orbitals, the “dd excitations”, were hot topics and could reliably be observed with the then state-of-the-art resolution of 100-200 meV. Magnetism and magnetic ordering are central questions in the study of correlated electron systems. For example, the layered perovskite Iridates showing strikingly similar magnetic exchange interactions as the Cuprates, implying that unconventional superconductivity might be found here, to the intriguing assertion that magnetic properties of honeycomb Iridates might point to a quantum spin liquid as ground state of this material, the spectrum of novel, exotic properties uncovered or anticipated promise a treasure trove of scientific discoveries. In the late 2000s, RIXS was established as a probe of magnetic excitations. However, spectral features associated with magnetic excitations (“magnons”) lie at a fraction of an eV or even in the sub-10meV regime. A significant advance in energy resolution is needed to attack such subjects with RIXS.

>Read more on the Advanced Photon Source website

Figure: Schematic rendering of the new flat-crystal RIXS spectrometer.

Kilian Peter Heeg wins ESRF Young Scientist award

Kilian Peter Heeg has been awarded the title of Young Scientist 2018 by the ESRF User Organisation in recognition of his pioneering work on light-matter interactions enabling resonant brilliance enhancement of X-ray pulses. This award is presented every year at the ESRF annual User Meeting to a scientist aged 37 or younger for outstanding work conducted at the ESRF.

Kilian Heeg is a physicist and postdoctoral researcher at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Aged just 31, Kilian has already significantly shaped the field of X-ray quantum optics.

Kilian says: “I wanted to be a mathematician when I was a child and I was always fascinated by natural sciences. However in my final years in school I fell in love with physics and very quickly became fascinated with quantum mechanics and especially quantum optics. I feel very honoured and pleased to have been chosen as the winner of this year’s ESRF Young Scientist Award.”

>Read more on the ESRF website

Image: Kilian on ESRF’s ID18 beamline
Credit: ESRF/C. Argoud

Questioning the universality of the charge density wave nature…

… in electron-doped cuprates

The first superconductor materials discovered offer no electrical resistance to a current only at extremely low temperatures (less than 30 K or −243.2°C). The discovery of materials that show superconductivity at much higher temperatures (up to 138 K or −135°C) are called high-temperature superconductors (HTSC). For the last 30 years, scientists have researched cuprate materials, which contain copper-oxide planes in their structures, for their high-temperature superconducting abilities. To understand the superconducting behavior in the cuprates, researchers have looked to correlations with the charge density wave (CDW), caused by the ordered quantum field of electrons in the material. It has been assumed that the CDW in a normal (non-superconducting) state is indicative of the electron behavior at the lower temperature superconducting state. A team of scientists from SLAC, Japan, and Michigan compared the traits of superconducting and non-superconducting cuprate materials in the normal state to test if the CDW is correlated to superconductivity.

>Read more on the SSRL website

Picture: explanation in detail to read in the full scientific highlight (SSRL website)




G. Ghiringhelli and L. Braicovich win 2018 Europhysics Prize of Condensed Matter

>Read more on the ESRF website


First users welcomed to I21

Diamond’s Inelastic X-ray Scattering beamline has celebrated an important milestone.

This new beamline is dedicated to Resonant Inelastic X-ray Scattering (RIXS) producing highly monochromatised, focused and tunable X-rays. It is suited to investigate the electronic, magnetic and lattice dynamics of samples particularly those with magnetic and electronic interactions.

“Considering the exceptional progress of the RIXS technique in the last few years, and the unique capabilities that I21 will offer to our UK and international community, we are extremely pleased to celebrate first users on I21,” says Laurent Chapon, Physical Sciences Director at Diamond. “Dr Kejin Zhou and his team, Diamond’s engineers and all support groups have worked incredibly hard to deliver this new beamline with an energy resolution and count rates already very close to the expected final targets. This is just the start of a great adventure, and we are looking forward to exploiting I21’s high-resolution for measurements of local and collective excitations in solid state materials. Our future investments to extend the energy range as well as delivering a polarimeter will reinforce the position of I21 as a world-leading facility.”

>Read More on the Diamond Light Source website

Photo: The I21 beamline time with first users from university of Bristol.