Steve Collins

My research is mostly within the realm of physics – either of the physics of phenomena arising from the interaction of x-rays with matter, or of the materials under investigation such as magnetic materials. The aims of my research are three-fold. The first is to study fundamental aspects of photon-matter interactions, highlighting unusual spectroscopic and polarization-dependent features, exotic wave fields in crystals, temperature effects in the absorption and diffraction of x-rays, for example. These phenomena are of interest in their own right and often have important counterparts in other areas of science such as optics. The second aim to to exploit these phenomena as new experimental techniques. Finally, the techniques are applied to real problems in materials physics.

Scientific projects have been shaped largely by the collaborations that I enjoy with several world-leading theoreticians and experimental scientists. A recent example is the twisting of the atomic magnetic pattern in 'weak ferromagnets'. Here, we were able to demonstrate a new approach for determining the phase of the x-ray diffraction signal, which is not usually observed, and to use this information to determine the direction of the magnetic twist. This result was used to verify a state-of-the-art theoretical model, which has applications in materials such as magnetoelectrics - very much in-vogue due to their potential technological applications. Our recent research on x-ray birefringence has lead to a surprising number of applications, including polarimetry, dynamics of guest-host structures and the first example of x-ray birefringence imaging. With theoretician colleagues we have shown how such effects can play an essential role in the in interpretation of x-ray diffraction data.

Most of this work has been carried out on Beamline I16 and similar facilities at Diamond, the ESRF and elsewhere. One important research activity outside of Diamond is a collaborative project with scientists at the APS (USA), to develop novel x-ray optics for ultra-high-resolution inelastic x-ray scattering. Recently experiments have demonstrated spectacular performance of a prototype IXS spectrometer. My interests in inelastic x-ray scattering also extend to higher energies, where we are engaged in a project to exploit Compton scattering to extract information about novel magnetic states.

Collaborations in which I am involved include:

• Shubnikov Institute of Crystallography RAS, Moscow, Russia. Moscow State University, Moscow, Russia. SIMaP, CNRS, Grenoble, France. This collaboration involved theoretical and experimental colleagues with a shared interest in x-ray physics. The projects are largely focused on resonant magnetic scattering. Recent work has focused on novel interference experiments to reveal the phase of the magnetic scattering signal and unusual temperature dependent effects in x-ray diffraction.
   
• Cardiff University, Cardiff, Wales. Institut Neel CNRS, Grenoble, France. This work is a continuation of an established collaboration to study the effects of birefringence and linear dichroism in highly anisotropic materials. Recent results include a study of the dynamics of molecular ordering in guest-host structures, the first observation of x-ray birefringence imaging, and calculations of the effects of birefringence on magnetic x-ray scattering data.
   
• Advanced Photon Source, Argonne National Laboratory, IL, USA Diamond enjoys an active collaboration with the APS towards the development of novel optics for ultra-high-resolution inelastic x-ray scattering. We have recently obtained spectacular results at the APS from a prototype spectrometer which included components designed and built at Diamond.

As Scientific Training and Education Coordinator at Diamond and Principle Beamline Scientist for Beamline I16 (Materials & Magnetism), I share my time between these activities as well as research activities. As a scientist, a significant fraction of my work is inevitable aimed at the support of the wider scientific community, via peer-review, committees, talks to scientific and non-scientific audiences, student training, etc. Finally, I have a interest in computing, for data analysis, modeling, and ultimately playing a far more significant role in science than is presently the case.