LNS - Scientific Highlights

Revealing the predominant driving force behind symmetry breaking in correlated materials is sometimes a formidable task due to the intertwined nature of different degrees of freedom. This is the case for La_2−xSr_xNiO_4+δ, in which coupled incommensurate charge and spin stripes form at low temperatures. Here, we use resonant x-ray photon correlation spectroscopy to study the temporal stability and domain memory of the charge and spin stripes in La_2−xSr_xNiO_4+δ.

PbMO₃ (M = 3d transition metals) family shows systematic variations in charge distribution and intriguing physical properties due to its delicate energy balance between Pb 6s and transition metal 3d orbitals. However, the detailed structure and physical properties of PbFeO₃ remain unclear. Herein, we reveal that PbFeO₃ crystallizes into an unusual 2a_p × 6a_p × 2a_p orthorhombic perovskite super unit cell with space group C_mcm.

The unconventional normal-state properties of the cuprates are often discussed in terms of emergent electronic order that onsets below a putative critical doping of x_c≈0.19. Charge density wave (CDW) correlations represent one such order; however, experimental evidence for such order generally spans a limited range of doping that falls short of the critical value x_c, leading to questions regarding its essential relevance. Here, we use X-ray diffraction to demonstrate that CDW correlations in La_2−xSr_xCuO₄ persist up to a doping of at least x=0.21.

The discovery of superconductivity in a d^9−δ nickelate has inspired disparate theoretical perspectives regarding the essential physics of this class of materials. A key issue is the magnitude of the magnetic superexchange, which relates to whether cuprate-like high-temperature nickelate superconductivity could be realized. We address this question using Ni L-edge and O K-edge spectroscopy of the reduced d^9−1/3 trilayer nickelates R₄Ni₃O₈ (where R = La, Pr) and associated theoretical modeling.

We have recently shown how a polarized beam in Talbot-Lau interferometric imaging can be used to analyze strong magnetic fields through the spin dependent differential phase effect at field gradients. While in that case an adiabatic spin coupling with the sample field is required, here we investigate a nonadiabatic coupling causing a spatial splitting of the neutron spin states with respect to the external magnetic field. This subsequently leads to no phase contrast signal but a loss of interferometer visibility referred to as dark-field contrast.

We study the gas diffusion in still liquids under gas high pressures. We demonstrate that the pressure-induced gas diffusion, liquid swelling and the liquid surface tension can be measured simultaneously in a one-pot experiment. The measurements are performed using the high-resolution neutron imaging in a non-tactile way. A major advantage of this new method is that the determination of surface tension necessitate no assumptions imposed on the properties of the liquid.

Perovskite oxynitride materials can act as effective photocatalysts for water splitting driven by visible light. A combined neutron and x-ray study now provides unique insight into the underlying processes at the solid–liquid interface and highlights how solar-to-hydrogen conversion can be improved.

The first application of stroboscopic neutron diffraction to studying lithium-ion batteries during operation establishes a new approach to unravelling the complex processes playing out in energy-storage materials.

The first application of stroboscopic neutron diffraction to studying lithium-ion batteries during operation establishes a new approach to unravelling the complex processes playing out in energy-storage materials.

LaTiO_xN_y oxynitride thin films are employed to study the surface modifications at the solid- liquid interface that occur during photoelectrocatalytic water splitting. Neutron reflectometry and grazing incidence x-ray absorption spectroscopy were utilised to distinguish between the surface and bulk signals, with a surface sensitivity of 3 nm.

With experimental work demonstrating that the correlated ground state of the pyrochlore system Ce₂Sn₂O₇ is a quantum liquid of magnetic octupoles, an international team led by PSI researcher Romain Sibille establishes a fundamentally new state of matter: higher-rank multipole ice.

Detailed understanding of charge diffusion processes in a lithium-ion battery is crucial to enable its systematic improvement. Experimental investigation of diffusion at the interface between active particles and the electrolyte is challenging but warrants investigation as it can introduce resistances that, for example, limit the charge and discharge rates. Here, we show an approach to study diffusion at interfaces using muon spin spectroscopy.

Topological properties of materials are of fundamental as well as practical importance. Of particular interest are unconven- tional superconductors that break time-reversal symmetry, for which the superconducting state is protected topologically and vortices can host Majorana fermions with potential use in quantum computing. However, in striking contrast to the unconventional A phase of superfluid ³He where chiral symmetry was directly observed, .....

Magnetic topological phases of quantum matter are an emerging frontier in physics and material science. Along these lines, several kagome magnets have appeared as the most promising platforms. Here, we explore magnetic correlations in the kagome magnet Co₃Sn₂S₂. Using muon spin-rotation, we present evidence for competing magnetic orders in the kagome lattice of this compound.

We investigate the Sn composition dependence of the Yb valence and local magnetization in YbMn₆Ge_6−xSn_x (4.25 􏰁≤x≤ 5.80) using x-ray absorption spectroscopy (XANES) and x-ray magnetic circular dichroism at the Yb L₃ edge. In these materials, where Mn is ferromagnetically ordered, we observe a decrease of the Yb valence upon reducing the chemical pressure by Sn doping and a suppression of the Yb magnetic moment for strongly hybridized  4f states (ν ∼ 2.77).

We report the discovery of topological magnetism in the candidate magnetic Weyl semimetal CeAlGe. Using neutron scattering we find this system to host several incommensurate, square-coordinated multi-k⃗ magnetic phases below T_N. The topological properties of a phase stable at intermediate magnetic fields parallel to the c axis are suggested by observation of a topological Hall effect.