Resonant Soft X-Ray Scattering from Stripe-Ordered ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Ba}}_{x}{\mathrm{Cu}\mathrm{O}}_{4}$ Detected by a Transition-Edge Sensor Array Detector

Resonant Soft X-Ray Scattering from Stripe-Ordered ${La}_{2 - x} {Ba}_{x} {Cu O}_{4}$ Detected by a Transition-Edge Sensor Array Detector

Young Il Joe, Yizhi Fang, Sangjun Lee, Stella X.L. Sun, Gilberto A. de la Peña, William B. Doriese, Kelsey M. Morgan, Joseph W. Fowler, Leila R. Vale, Fanny Rodolakis, Jessica L. McChesney, Joel N. Ullom, Daniel S. Swetz, and Peter Abbamonte

Phys. Rev. Applied 13, 034026 – Published 10 March 2020

Abstract

Resonant soft x-ray scattering (RSXS) is a leading probe of valence-band order in materials best known for detecting charge-density-wave order in copper-oxide superconductors. One of the biggest limitations on the RSXS technique is the presence of a severe fluorescence background, which, like the RSXS cross section itself, is enhanced under resonant conditions. This background prevents the study of weak signals such as diffuse scattering from glassy or fluctuating order that is spread widely over momentum space. Recent advances in superconducting transition-edge-sensor (TES) detectors have led to major improvements in energy resolution and detection efficiency in the soft x-ray range. Here, we perform a RSXS study of stripe-ordered ${La}_{2 - x} {Ba}_{x} {Cu O}_{4}$ at the $Cu$ $L_{3 / 2}$ edge (932.2 eV) using a TES detector with 1.5-eV resolution, to evaluate its utility for mitigating the fluorescence-background problem. We find that, for suitable degree of detuning from the resonance, the TES rejects the fluorescence background, leading to a five to ten times improvement in the statistical quality of the data compared to an equivalent, energy-integrated measurement. We conclude that a TES presents a promising approach to reducing background in RSXS studies and may lead to discoveries in materials exhibiting valence-band order that is fluctuating or glassy.

Received 29 July 2019
Revised 19 January 2020
Accepted 7 February 2020

DOI:https://doi.org/10.1103/PhysRevApplied.13.034026

Physics Subject Headings (PhySH)

Charge density waves Optoelectronics X-ray beams & optics

Solid-state detectors Strongly correlated systems Superconducting devices

Radiation detectors Resonant elastic x-ray scattering

Interdisciplinary PhysicsCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Young Il Joe¹, Yizhi Fang², Sangjun Lee ², Stella X.L. Sun ², Gilberto A. de la Peña², William B. Doriese ¹, Kelsey M. Morgan ¹, Joseph W. Fowler¹, Leila R. Vale¹, Fanny Rodolakis³, Jessica L. McChesney³, Joel N. Ullom¹, Daniel S. Swetz¹, and Peter Abbamonte ^2,*

¹National Institute of Standards and Technology, Boulder, Colorado 80305, USA
²Department of Physics and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
³Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA

^*abbamonte@mrl.illinois.edu

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 13, Iss. 3 — March 2020

Subject Areas

Reuse & Permissions

Access Options

Article Available via CHORUS

Download Accepted Manuscript

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Schematic of the TES and RSXS scattering setup at Sector 29 at the Advanced Photon Source. (a) Layout of the scattering chamber (gray) showing the location of the TES detector snout and cryostat (yellow). The TES is connected to the chamber via a vacuum bellows and can be slid in and out of its port to change the sample distance. In these experiments, the full detector array covered approximately 11 degrees of scattering angle. (b) Expanded view of the sensor head (yellow) and detector array (green). The TES consists of 240 individually addressable sensors. The data presented here are taken with a 24-element subsector of the array (orange expanded view).
Reuse & Permissions
Figure 2
(a) Resolution function of the TES (blue curve) determined from diffuse elastic scattering from a thin layer of gold on polished silicon at a fixed incident beam energy of 920 eV. Fit function used in analysis of the data (orange curve). (b) LBCO spectrum taken with sensor no. 15 far from the CDW Bragg condition showing elastic, $d$ - $d$ , and fluorescence emission features in the data. The colored lines represent the different components of the fit model (see text). The spectrum is measured at a fixed incident beam energy of 938.9 eV. $Cu$ $L_{3 / 2}$ XAS spectrum of LBCO showing the absorption maximum. The XAS curve is plotted against incident photon energy while the other curves are ploitted against scattered photon energy.
Reuse & Permissions
Figure 3
Incident energy dependence of the scattered intensity from LBCO as measured by the 24 active sensors in the TES array. The panels are arranged to roughly correspond to the sensor layout shown in Fig. 1. The incident photon energy is tuned from 929.2 to 935.8 eV in 0.5-eV steps. The sample angle is changed from ${35.1}^{\circ}$ to ${35.3}^{\circ}$ , in coordination with the incident beam energy, to keep the in-plane component of the momentum transfer fixed during the scan. The CDW signal is observed in sensor no. 25 whose location corresponds to a momentum vector $q = (0.23, 0, 1.54)$ . The red lines indicate the location of the elastic scattering ( $ω_{i} = ω_{s}$ ).
Reuse & Permissions
Figure 4
Sample angle dependence of the scattered intensity from LBCO. This data set is essentially a scan of the momentum transfer vector of each of the 24 active sensors of the TES detector. The panels are numbered according to the naming convention in Fig. 1. The CDW is visible as a peak at the scattered energy of 933.7 eV, which corresponds to the incident beam energy. The CDW sweeps across sensors 9, 5, 25, and 31.
Reuse & Permissions
Figure 5
Application of the fit model to the TES spectra from sensors no. 5 and no. 25. Each curve represents a cut as a function of scattered photon energy through panels no. 5 and no. 25 in Figs. 3 and 4. Some of the spectra are scaled for visibility. (a) Individual TES spectra for sensor no. 5 for various incident beam energies, from Fig. 3. Solid lines show different terms in the fit model and open circles are the experimental data points. (b) Same plot as (a) for sensor no. 25, where the CDW scattering is strongest. At each incident beam energy the sample angle is changed in a coordinated way to keep the momentum transfer vector fixed. (c) Individual TES spectra for sensor no. 5 for various sample angles, showing enhanced elastic CDW scattering for $θ = {34.55}^{\circ}$ , from Fig. 4. (d) Same plot as (c) for sensor no. 25, showing enhanced elastic CDW scattering at $θ = {35.15}^{\circ}$ . The angle-dependent spectra are taken at a fixed incident energy of 933.7 eV.
Reuse & Permissions
Figure 6
Incident energy and angle dependence of the elastic scattering, as determined by the data fits in Fig. 5, compared to what would have been measured with an equivalent, energy-integrating detector (energy-integrated curves are scaled to allow visual comparison). (a) Energy dependence of the elastic CDW scattering in sensor no. 5 (blue) compared to the energy-integrated result (red). The energy-integrated curve exhibits an asymmetry and edge jump due to significant contribution from background fluorescence. The XAS spectrum, also shown in Fig. 2, is displayed for comparison. (b) Same plot as (a) for sensor no. 25. (c) Angle dependence of the energy-integrated CDW scattering in sensor no. 5. The CDW peak is barely visible above the fluorescence background. (d) Same plot as (c) for sensor no. 25. (e) Angle dependence of the elastic CDW scattering in sensor no. 5 (blue) compared to the energy-integrated result (red). The background is removed from the energy-integrated data by subtracting a second-order polynomial fit, allowing a direct visual comparison between the points. The CDW feature is much more clearly revealed in the elastic scattering data. Its angular width of $1^{\circ}$ is consistent with prior studies [5] (f) Same plot as (e) for sensor no. 25.
Reuse & Permissions

Physical Review Applied

Resonant Soft X-Ray Scattering from Stripe-Ordered La2−xBaxCuO4 Detected by a Transition-Edge Sensor Array Detector

Young Il Joe, Yizhi Fang, Sangjun Lee, Stella X.L. Sun, Gilberto A. de la Peña, William B. Doriese, Kelsey M. Morgan, Joseph W. Fowler, Leila R. Vale, Fanny Rodolakis, Jessica L. McChesney, Joel N. Ullom, Daniel S. Swetz, and Peter Abbamonte

Phys. Rev. Applied 13, 034026 – Published 10 March 2020

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Subject Areas

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Resonant Soft X-Ray Scattering from Stripe-Ordered ${La}_{2 - x} {Ba}_{x} {Cu O}_{4}$ Detected by a Transition-Edge Sensor Array Detector