This talk will present resonant and non-resonant x-ray diffraction experiments upon uniaxial pressure application to cuprate superconductors. Special attention is given to the symmetry properties of charge stripe ordering.
Quantum magnets are physical realisations of many-body quantum systems which may host interesting phenomena such as entangled states or spin-nematic states and quantum phase transitions. There exists a number of experimental knobs for controlling the state of such system: Temperature, magnetic field, chemical doping and pressure. Of all these, the latter is the cleanest way of manipulating...
Potassium dihydrogen phosphate, KH$_2$PO$_4$ (KDP), is a classic, broadly used ferroelectric material. It is a model system of an order-disorder material, with a Curie temperature $T_C$ of 123 K. Above this temperature, it is a tetragonal paraelectric. Below, it becomes orthorhombic. In the 1940s, Slater wrote an order-disorder theory to describe rather well the physics of KDP [1]. However,...
The classification and deep understanding of phases of quantum matter is a necessary premise for utilizing quantum materials in all areas of modern and future electronics in a controlled and optimal way. In this respect, layered systems with highly anisotropic electronic properties have been found to be potential hosts for rich, unconventional and tunable exotic quantum states. Prominent...
Quantum materials exhibit rich phase diagrams, strongly sensitive to external parameters, which include intriguing properties such as magnetic and ferroelectric order, electronic correlations, superconductivity, and spin and charge order. These macroscopic properties arise from the complex interactions between electronic, structural, spin and orbital degrees of freedom. While key in defining...
Control of dimensionality in condensed matter continues to reveal novel quantum phenomena and effects. Transition metal phosphorous trichalcogenides TM P X 3 (TM = Mn, Fe, Ni, V, etc., X = S, Se) have proven to be ideal examples where structural, magnetic and electronic properties evolve into novel states when their dimensionality is tuned with pressure. At ambient pressure, they are...
Type-II multiferroic materials, in which ferroelectric polarization is induced by inversion-nonsymmetric magnetic order, promise new and highly efficient multifunctional applications based on the mutual control of magnetic and electric properties. Although this phenomenon has to date been limited to low temperatures, we have found a giant pressure-dependence of the multiferroic critical...
Interfacial tensions for systems containing model compounds for the freeze out from natural gas can be measured at high pressures by observing the interface shapes in tubes. Mobile interfaces in opaque tubes positioned parallel to gravity are easy to prepare and neutron imaging can provide related system properties (composition, density, etc.). We have observed the phase interfaces in the...
Researches on two-dimensional (2D) materials have attracted tremendous attention both from fundamental and applied sciences since accelerated by the discovery of graphene. Among a large number of 2D materials, chromium trihalides CrX3 (X = Cl, Br, I) van der Waals (vdW) magnets have also raised a large interest due to the existence of many magnetic subtleties that cannot be explained by their...
The demand for high-pressure equipment has doubled over the last decade at the Institut Laue-Langevin. To cope with this demand and ensure successful experiments, we have enhanced pressure generators and expanded our suite of pressure devices.
First, we have significantly improved the 1 GPa liquid pressure generators with:
- a comprehensive revamp of the automation program improving the...
Advanced high-pressure neutron scattering experiments demand a high neutron flux and precise phase space at small sample volumes, while maintaining a high signal-to-noise ratio. This work is dedicated to a comprehensive evaluation of background noise in high-pressure neutron scattering experiments, employing simulations and benchmark experiments. McStas 3.2 with the Union component is used to...
Strain in antiferromagnetic orthoferrite thin films is predicted to significantly change magnetic properties and result in a polar response up to room temperature. Orthorhombic DyFeO3 is of particular interest since the Fe-spins undergo a spin-reorientation with transition temperatures depending strongly on the Dy-Fe interaction and a magnetic field induced ferroelectric phase below...
High-temperature superconducting cuprates are a model system to examine the relationship between intertwined quantum phases. The competition has, however, been difficult to tune with external stimuli without inducing superconducting vortices by a magnetic field at the same time. In our study, we show that $c$-axis strain couples directly to the phase competition between charge stripe order and...
The demanding experimental conditions required to access the quantum critical behavior of many materials (including high magnetic fields, high pressures, and ultra-low temperatures), make their microscopic investigation often problematic. Over the years, techniques such as the nuclear magnetic resonance and muon-spin rotation/relaxation have emerged as complementary, well suited (and often...
External parameters have been shown to be a powerful tool for tuning the electronic or magnetic ground state of a material. Hydrostatic pressure is a widely used external parameter but can lead to issues in the experimental procedure, such as a large background or spurious responses. Specifically, within muon spin rotation (µ+SR), a significant share of the incoming muons can stop inside the...
In this contribution we present theoretical framework for quantitative modeling of surface tension of liquids and their mixtures under high pressures. We perform molecular dynamics (MD) simulations (in GROMACS [1]) and apply statistical thermodynamics of solutions (namely Kirkwood-Buff theory) [2,3]. This allows us to describe solution structure (distribution functions) not only in coexisting...
Hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (cHTG) have drawn considerable attention in recent years as a clean and renewable biocrude and synthetic natural gas (bio-SNG) production technology, respectively. Under the temperature (350-450°C) and pressure (200-300bars) typically used, water acts as the solvent and reactant, hence no drying step is required to convert...
In quantum magnets, simple degrees of freedom with short-range interactions lead to a plethora of emergent many-body phases with different exotic properties. Uniaxial pressure allows tuning these interactions selectively and engineer the underlying Hamiltonians. Hence, the properties of the emergent phases can be controlled on-demand.
One system where such selective tuning is very pertinent...
Over the last years, we have developed and implemented a few different designs of uniaxial pressure devices, specifically optimized for scattering experiments.
I will present the relevant considerations for such experiments, discuss selected recent results and introduce new in-situ devices available for the user program at SINQ.
[1] GS et al., to appear in Swiss Neutron News, vol. 62...
