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Abstract: The Remeika stannides (𝑅3T4Sn13, with R = rare earth/alkaline metals, T = transition metal, and X = p-block elements) have been extensively studied due to the interplay between the charge-density-wave (CDW) ordering and superconductivity often found in these materials. Here, we explore the relationship between these two orders in cubic La3Co4Sn13 by conducting electrical transport measurements under uniaxial stress along different crystallographic directions ([100], [110], and [111]). We find that the superconducting transition temperature (𝑇c) is suppressed under compression for all directions measured, in contrast to previous measurements under hydrostatic pressure. This indicates 𝑠-wave superconductivity. The CDW transition temperature is also suppressed under compression for all measured directions. The simultaneous suppression of superconductivity and CDW order suggests that changes in 𝑇c with uniaxial stress are mainly driven by changes in the electronic density of states and not a competition between these two orders.
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Jun 2026
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I05-ARPES
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Chan-Young
Lim
,
Francesc
Ballester
,
Arunava
Kar
,
Manex
Alkorta
,
David
Subires
,
Ji
Dai
,
Massimo
Tallarida
,
Elio
Vescovo
,
Timur K.
Kim
,
Cephise
Cacho
,
Changjiang
Yi
,
Subhajit
Roychowdhury
,
Avdhesh Kumar
Sharma
,
Yongseong
Choi
,
Gilberto
Fabbris
,
Joerg
Strempfer
,
Pierluigi
Gargiani
,
Chandra
Shekhar
,
Claudia
Felser
,
Ion
Errea
,
Maia G.
Vergniory
,
Santiago
Blanco-Canosa
Diamond Proposal Number(s):
[36505]
Abstract: Kagome materials are known for hosting emergent quantum phenomena driven by the interaction between different lattice, charge, and spin orders. Here, we present a detailed angle-resolved photoemission (ARPES), density functional theory (DFT), and x-ray magnetic circular dichroism (XMCD) study of the electronic and magnetic structure of 𝑅Ti3Bi4 (𝑅=Nd, Sm, Gd). ARPES and DFT demonstrate that the bulk electronic band structure is dominated by the hybridization of the Ti bands, and the weak electron-like pocket at Γ is identified as a surface state. The isotropic XAS profile of the 𝑀4,5 edge of the rare earth is consistent with the presence of the 𝑅3+ oxidation state. Using the XMCD sum rules, backed by the atomic-multiplet-theory calculations, we obtain the spin and orbital magnetic moments. The Ti 𝐿2,3-edge XMCD reveals the presence of a small magnetic moment in GdTi3Bi4, presumably driven by the proximity of the Ti kagome layers to the zigzag chains of Gd, while the total magnetic moment of Gd is shared by the 𝑓 and 𝑑 electrons. Our combined XMCD, ARPES, and DFT study provides an important piece of information to understand the spin-flip transitions and anomalous Hall effect observed in the 𝑅Ti3Bi4 kagome metals.
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Jun 2026
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I21-Resonant Inelastic X-ray Scattering (RIXS)
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Kunhao
Li
,
Qizhi
Li
,
Changwei
Zou
,
Jaewon
Choi
,
Chaohui
Yin
,
Mirian
Garcia-Fernandez
,
Stefano
Agrestini
,
Shilong
Zhang
,
Chengtian
Lin
,
Xingjiang
Zhou
,
Ke-Jin
Zhou
,
Yi
Lu
,
Yingying
Peng
Diamond Proposal Number(s):
[30361]
Abstract: The superconducting gap is a characteristic feature of high-𝑇c superconductors and provides crucial information on the pairing mechanism underlying high-temperature superconductivity. Here, we employ high-resolution resonant inelastic x-ray scattering (RIXS) at the Cu 𝐿3 edge to investigate the superconducting gap in the overdoped cuprate Bi2Sr2Ca2Cu3O10+𝛿 (𝑇c=107K). By analyzing antisymmetrized, temperature-dependent RIXS spectra over a range of in-plane momentum transfers, we observe a clear suppression of low-energy spectral weight below 𝑇c, indicative of superconducting-gap formation. This suppression is most pronounced at small momentum transfers [
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𝒒∥
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≤0.18 r.l.u. (reciprocal lattice units)] and corresponds to a gap size of approximately 2Δ0∼130 meV. Comparison with theoretical calculations of the momentum-dependent charge susceptibility supports a 𝑑-wave symmetry of the superconducting gap, while an isotropic 𝑠-wave gap fails to reproduce key experimental features. These findings establish RIXS as a powerful, bulk-sensitive probe of superconducting-gap symmetry and highlight its utility for studying materials beyond the reach of surface-sensitive techniques such as ARPES and STM.
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Jun 2026
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I15-Extreme Conditions
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Huixin
Hu
,
Israel
Osmond
,
Calum
Strain
,
Hannah A.
Shuttleworth
,
Callum R.
Stevens
,
Andrew
Huxley
,
Mikhail A.
Kuzovnikov
,
Federico A.
Gorelli
,
Eugene
Gregoryanz
,
Miriam
Pena-Alvarez
,
Philip
Dalladay-Simpson
,
Ross T.
Howie
Open Access
Abstract: Sulfur and selenium demonstrate one of the most complex behavior under high pressure among all elements of the periodic table. Despite being known to form interchalcogens, the properties of these compounds have not been widely explored in the dense state. Through a series of diamond anvil experiments combined with x-ray diffraction, optical spectroscopy, and electrical resistance measurements, we explore the properties of selenium disulfide (SeS2) up to pressures of 150 GPa. At ambient pressure, SeS2-I represents a substitutional solid solution of S and Se atoms, forming an eight-membered molecular ring arrangement analogous to γ -S. The band gap of SeS2-I rapidly closes upon compression, and above 27 GPa, there is a transformation to a metallic tetragonal phase (SeS2-III), in which atoms form square helical chains. Upon further compression, we observe a phase sequence from incommensurate modulated SeS2-IV above 59 GPa, transforming to rhombohedral SeS2-V by 116 GPa.
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Jun 2026
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I05-ARPES
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Diamond Proposal Number(s):
[28484, 31262]
Open Access
Abstract: We report pressure-induced metallization in BaMn2P2 based on resistivity measurements in a diamond anvil cell. At ambient pressure, the temperature-dependent resistivity is well described by a two-gap Arrhenius model, yielding intrinsic and extrinsic activation energies of approximately 0.2 and 0.04 eV, respectively. Angle-resolved photoemission spectroscopy (ARPES) shows no detectable spectral weight at the Fermi level within the measured momentum window. The growth of spectral weight at higher binding energies is consistent with the energy scales inferred from transport measurements. Under pressure, the temperature dependence of the resistivity evolves from insulatinglike to mixed-slope behavior and becomes metallic above Pc ≈ 7 GPa, with no low-temperature upturn. The resistivity ratio R(P) = ρ(100 K)/ρ(300 K) also drops abruptly near Pc. A baseline transport model combining Bloch-Grüneisen phonon scattering with a thermally activated carrier density fails to reproduce this sharp change for any smoothly varying activation energy. Temperature- and pressure-dependent x-ray diffraction shows smooth evolution of V with no symmetry change and no resolvable discontinuity at Pc . Taken together, these results indicate an abrupt pressure-driven metallization near Pc, with no evidence for a structural phase transition within our experimental resolution.
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May 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[34932]
Open Access
Abstract: The atomic-scale structure and melting curve of liquid mercury was measured using in situ synchrotron x-ray diffraction (SXRD) at pressure and temperature (𝑝−𝑇) conditions up to 9.44(2) GPa and 651(1) K. Ab initio molecular dynamics (AIMD) simulations were employed to obtain a detailed atomistic model of the liquid structure. The results reveal a pronounced flattening, and potential maximum, in the measured melting curve between 6 and 9 GPa. The structure factors 𝑆HgHg(𝑄) and pair distribution functions 𝑔HgHg(𝑟)calculated from the AIMD simulations are in good overall agreement with the SXRD measurements under comparable reduced densities and temperatures, indicating that the atomistic structure of liquid Hg is well captured by AIMD. With increasing pressure, the principal peak in 𝑆HgHg(𝑄) shifts to higher 𝑄, with the subsidiary peak at 𝑄=2𝑘Fexperiencing a concomitant shift consistent with the increased electron density. Considering the Evans 𝑡-matrix formulation of the Ziman theory of liquid metals, the structural 𝑆(2𝑘F) term is expected to have only a weak influence on the electrical resistivity under compression. In contrast, the pressure-induced broadening and shift of the 𝑑-projected density of states towards the Fermi level is consistent with enhanced near-resonant 𝑑-electron scattering, and a corresponding increase in resistivity, analogous to the behavior of first-row transition metals. Analysis of the measured 𝑔HgHg(𝑟) functions, and AIMD trajectories in real space, indicates that the liquid structure experiences a progressive development towards simple hard-sphere-like behavior at increasing 𝑝−𝑇along the melting curve. However, topological cluster classification analysis shows that while the structural fingerprint of liquid Hg strongly resembles an effective hard-sphere system, even at the highest pressures investigated it contains more many-body motifs than expected for this simple model.
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May 2026
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I21-Resonant Inelastic X-ray Scattering (RIXS)
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Diamond Proposal Number(s):
[29150]
Open Access
Abstract: Cuprate superconductors show various collective charge correlations that are intimately connected with their electronic properties. In particular, charge order in the form of an incommensurate charge density wave (CDW) order with an in-plane wave vector 𝛿CDW≈0.23–0.35 reciprocal lattice units appears to be universally present. In addition to CDW, dynamic charge density fluctuations (CDFs) are also present with wave vectors comparable to 𝛿CDW. CDFs are present up to ≈300K and have relatively short correlation lengths of 𝜉≈20Å. Here we use Cu-𝐿3 and O-𝐾 resonant inelastic x-ray scattering (RIXS) to study the doping dependence of CDW and CDFs in La2−𝑥Sr𝑥CuO4. We fit our data with (quasi)elastic peaks resulting from the CDW and up to four inelastic modes associated with oxygen phonons that can be strongly coupled to the CDFs. Our analysis allows us to separate the charge correlations into three components: the CDW with wave vector 𝛿4𝑎-CDW≈0.24 and two CDF components with 𝛿4𝑎-CDF≈0.24 and 𝛿3𝑎-CDF≈0.30. We find that for 𝑇≈𝑇𝑐 the CDW coexists with the CDFs for dopings near 𝑥=𝑝≈1/8. The 4𝑎-CDW disappears beyond 𝑥=0.16 and the 4𝑎-CDF beyond 𝑥=0.19, leaving only a weak 3𝑎-CDF at the highest doping studied, 𝑥=0.22. Our data suggest that low-energy charge fluctuations exist up to doping 𝑥=0.19=𝑝★, where the pseudogap disappears; however, we find no evidence that they are associated with a quantum critical point.
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May 2026
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[30765, 30768]
Abstract: We present fine momentum space resolution resonant elastic x-ray scattering measurements of the magnetic structure of the metallic antiferromagnet CoNb3S6. Using circular dichroism and full linear polarization analysis of the magnetic scattering, we reveal a noncoplanar double-𝑸 (2𝑄) order that is comprised of a noncollinear commensurate component and a long-wavelength incommensurate helical component. This 2𝑄 magnetic structure exhibits a staggered scalar spin chirality that forms a modulated stripe like pattern with no uniform component. Measurements of the magnetic structure across many samples reveal a complex domain pattern associated with the magnetic ordering and suggest a lowering of the structural symmetry in CoNb3S6. We present a symmetry analysis demonstrating that the observed 2𝑄 magnetic order breaks all necessary symmetries to enable an anomalous Hall effect and further show how this magnetic order can be naturally explained by four-spin exchange interactions in a metallic magnet. The identification of the magnetic order, associated symmetry breaking, and explanation of its origin provides insight into the mechanism of the unconventional magnetotransport phenomena in CoNb3S6 and thus can help to determine potential routes for realizing novel electronic phenomena in metallic antiferromagnets.
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May 2026
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I16-Materials and Magnetism
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N.
Qureshi
,
A. M.
Vibhakar
,
K.
Beauvois
,
J. A.
Rodríguez-Velamazán
,
A.
Stunault
,
R.
Scatena
,
F.
Carneiro
,
A.
Bombardi
,
C. J.
Won
,
K.
Du
,
S.-W.
Cheong
Diamond Proposal Number(s):
[33189, 31138]
Abstract: We present a combined x-ray and polarized neutron scattering study on chiral, polar and magnetoeletric NiCo2TeO6 single crystals with different net crystal chiralities as characterized by optical methods. The rastering images taken with a micrometer-sized polarized x-ray beam unambiguously reveal the coupling of crystal and magnetic chiralities in a heterochiral sample. Spherical neutron polarimetry experiments on a different, structurally enantiopure sample—as evidenced by polarized x-ray scattering—reveal a homochiral magnetic spiral, which proves the stabilization of a single helical handedness despite the intertwined structural helices in the ferri-chiral crystal structure.
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Mar 2026
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Open Access
Abstract: Static compression experiments using diamond anvil cells (DAC), combined with x-ray diffraction (XRD) are widely used to study material properties at extreme pressures. Recent advances enable time-resolved XRD during dynamic compression along tailored loading paths. However, the influence of compression rate on derived properties remains poorly understood, and the use of tailored compression paths—particularly pressure cycling—requires further investigation. Here, we employed time-resolved XRD in a dynamic DAC to compress MgO in a Ne pressure medium along a tailored compression path consisting of a ramp, plateau, and cyclic loading. Pressure-volume relations derived from ramp compressions at average compression rates of 0.22 and 0.46GPas−1 agree closely with previous static experiments, with minor but detectable systematic deviations in the faster compression run. Stress analysis suggests that this deviation might be related to an increased flow strength of Ne under fast compression. During the postramp plateaus, MgO pressures continued to increase, highlighting the effect of compression rate on the time required for the coupled mechanical DAC system to reach equilibrium. Under cyclic loading, we observe phase shifts between oscillating differential stresses and volume strains in Ne, possibly indicating that viscoelastic/-plastic behavior of either Ne or the gasket material contributed to the overall response. We found this effect more pronounced for lower frequencies and larger cycling amplitudes. The findings presented in this paper improve our understanding of material behavior during dynamic loading in the DAC and provide reference data and methodology for studies of complex materials and loading paths.
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Mar 2026
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