This presentation will introduce and exemplify the artificial intelligence tools that my group have been developing with ISIS. These use data-mining and machine-learning methods to build data-science platforms that aid materials characterisation and materials application methods. These include the incorporation of neutron scattering data. I will also show some examples of how these...
As part of our efforts in the field of autonomous instrument control, we present a path-finding algorithm and implementation for triple-axis spectrometers. Due to angular constraints in the instrument space, as well as from obstacles such as walls, not every (Q, E) coordinate point is accessible for the instrument. A careful mapping of the available positions is usually required before...
The advent of inelastic neutron scattering in the middle of the last century enabled detailed studies of lattice vibrations, i.e. phonons, in condensed matter. Initially focused on simple structures [1,2], inelastic neutron scattering has been instrumental for our understanding of superconductivity in A15 compounds [3] and more recent conventional superconductors [4,5]. However, many materials...
Recent experiences have highlighted that in order to ensure the continued success of neutron scattering as a method, user support must be improved not only at the facilities, but also while users are still in the planning, proposal-writing and preparation stages of an experiment.
Digital twins, which provide a virtual copy of neutron scattering instruments and their user interface(s), are an...
The recent decades have seen a constant and fruitful development of neutron spectrometers of the triple-axis type. Different ways of multiplexing have been implemented and a number of instruments are performing user experiments regularly, while some have recently been replaced by even better instruments. In this overview, I will review the common designs and their typical use cases at a number...
Neutron spectroscopic methods are indispensable tools to study dynamical processes such as diffusion, magnetic excitations and even electronic excitations.
The small signal size and the flux limitation of neutron sources result in long counting times. Moreover, the requirement of special sample environment to perform spectroscopic studies at extreme conditions affects the signal to noise ratio...
Pyrochlores magnets, spin ice and quantum spin ice physics: the neutron scattering perspective
Sylvain PETIT1, Elsa LHOTEL2, Mélanie LEGER1,2 Monica CIOMAGA HATNEAN3, Jacques OLLIVIER4, Andrew R. WILDES4, Stéphane RAYMOND5, Eric RESSOUCHE5, Geetha BALAKRISHNAN3
1Institut Néel, CNRS and Université Grenoble Alpes, 38000 Grenoble, France
2Laboratoire Léon Brillouin, Université Paris-Saclay,...
We will discuss a framework for modeling and understanding the magnetic excitations in localized, intermediate coupling magnets where the interplay between spin-orbit coupling, magnetic exchange, and crystal-field effects create unconventional ground states. A spin-orbit exciton approach for modelling these excitations is developed based upon a Hamiltonian which explicitly incorporates...
Clathrate hydrates are are crystalline water-based solids (similar to ice), which form cages that are able to host guest molecules. The guests are trapped in cavities of the hosts, that are composed of hydrogen-bonded water molecules. Tetrahydrofuran (THF) clathrate hydrates (fully or partially deuterated) seem particularly well suited as a moderation medium for neutron, as they possess...
Decades of theoretical, numerical and experimental studies have sought quantum systems, beyond the classical picture of conventional magnetism, focusing on low-dimensional S = 1/2 materials. The characteristic features of such systems are the lack of long-range magnetic order and the presence of deconfined fractional spin-1/2 excitations called spinons. Owing of the exact solution of the spin-...
Each of you will be familiar with the well-known chart of the dependence of the flux of large synchrotron and neutron infrastructures on time. While synchrotron power continues to increase by orders of magnitude, neutrons reached their highest power 50 years ago at ILL and it will be slightly surpassed with the help of ESS. Therefore, scientists have been trying for decades to optimize optics,...
Panther is a new thermal-neutron direct-geometry hybrid time-of-flight spectrometer at the Institut Laue-Langevin. Phase-1 of the project is completed, and the design and performance of the instrument will be discussed. Panther is equipped with two double focusing monochromators: a pyrolytic graphite for which the (002), (004), and (006) reflections are routinely used, and a copper...
The inverse-geometry inelastic neutron spectrometer NERA has already been operating for more than three decades and during that time has proven to be a very successful machine for broadband chemical spectroscopy with neutrons. To continue the research using the best modern technologies, the project of a new inverse-geometry inelastic neutron spectrometer has been started. New instrument will...
Modern time-of-flight neutron spectrometers routinely collect datasets covering volumetric reciprocal space. By taking advantage of multiplexing techniques or parametric studies datasets can exceed one billion independent observations. Software exists to facilitate collecting observations from volumetric datasets in arbitrary, user-defined, regions of reciprocal space; which can often be...
Molecular nanomagnets are model systems to study the spin dynamics and magnetic correlations in low dimensional magnets. The advances in the chemical engineering of magnetic molecules have allowed the synthesis of tailor-made systems which provide promising architectures for the realization of quantum computers.
Molecular nanomagnet can display relatively long coherence time, can host...
A.C. Ferreira, S. Paofai, A. Létoublon, J. Ollivier, S. Raymond, B. Hehlen, B. Rufflé, C. Katan, J. Even, and Ph. Bourges
Hybrid organolead perovskites (HOP) have started to establish themselves in the field of photovoltaics, mainly due to their great optoelectronic properties and steadily improving solar cell efficiency. Although much recent attention has been devoted towards unraveling...
Chasing new states of quantum matter is a central element in condensed matter physics, motivated both by fundamental curiosity but also by the need for a better understanding of many-body quantum effects for future technologies. Of particular interest are frustrated magnets where competing interactions may lead to exotic magnetic states and an external parameter such as magnetic field or...
Cubic cadmium(II) cyanide is amongst the most important isotropic negative thermal expansion (NTE) materials, with behavior more than twice as extreme as that of better known systems such as ZrW$_2$O$_8$. We investigate the relationship between the geometrically frustrated orientational order of the molecular CN$^-$ anion the system’s lattice dynamics. Inelastic neutron scattering (INS) is...
During the past decades, research in materials science has been accelerated by the rapid development of synchrotron and neutron sources.1 Conventional data analysis approaches using minimization techniques, such as least-squares fitting algorithms, cannot keep up with the amount of increasing size of measured datasets. Consequently, data analysis is becoming a bottleneck for research in...
