X-ray magnetic diffraction under high pressure.

Yishu Wang,Yejun Feng,T F Rosenbaum

doi:10.1107/s2052252519007061

Abstract

Advances in both non-resonant and resonant X-ray magnetic diffraction since the 1980s have provided researchers with a powerful tool for exploring the spin, orbital and ion degrees of freedom in magnetic solids, as well as parsing their interplay. Here, we discuss key issues for performing X-ray magnetic diffraction on single-crystal samples under high pressure (above 40 GPa) and at cryogenic temperatures (4 K). We present case studies of both non-resonant and resonant X-ray magnetic diffraction under pressure for a spin-flip transition in an incommensurate spin-density-wave material and a continuous quantum phase transition of a commensurate all-in-all-out antiferromagnet. Both cases use diamond-anvil-cell technologies at third-generation synchrotron radiation sources. In addition to the exploration of the athermal emergence and evolution of antiferromagnetism discussed here, these techniques can be applied to the study of the pressure evolution of weak charge order such as charge-density waves, antiferro-type orbital order, the charge anisotropic tensor susceptibility and charge superlattices associated with either primary spin order or softened phonons.

Highlights

In the early 20th century, quasi-hydrostatic pressure in the GPa range was recognized as an elegant and effective tuning technique to continuously manipulate the properties of materials (Bridgman, 1912)
We focus in this article on high-pressure X-ray magnetic diffraction in a diamond-anvil cells (DACs) environment, techniques that have emerged over the last two decades
The discussion is primarily based on our experience at Sector 4-ID-D of the Advanced Photon Source (APS), but the general principles are applicable to beamlines at many different synchrotron radiation sources (Paolasini et al, 2007; Strempfer et al, 2013)

Summary

Introduction

In the early 20th century, quasi-hydrostatic pressure in the GPa range was recognized as an elegant and effective tuning technique to continuously manipulate the properties of materials (Bridgman, 1912). A variety of experimental techniques have been developed to probe both ground states and excitations of ion, charge and spin degrees of freedom in a DAC-based pressure environment. These include electrical transport (Derr et al, 2008; Jaramillo et al, 2010), AC magnetic susceptibility (Debessai et al, 2009; Palmer et al, 2015) and heat capacity/calorimetry (Demuer et al, 2000) for studying the bulk properties of materials under pressure. To optimize the measurement efficiency under the constraints of a synchrotron radiation source, emphasis needs to be placed on (1) the components of both the X-ray diffraction and the highpressure setups, as well as (2) maintaining sample quality in a low-temperature, high-pressure environment. The discussion is primarily based on our experience at Sector 4-ID-D of the Advanced Photon Source (APS), but the general principles are applicable to beamlines at many different synchrotron radiation sources (Paolasini et al, 2007; Strempfer et al, 2013)

X-ray optics

The high-pressure sample environment

Outlook

Funding information