I16-Materials and Magnetism
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Diamond Proposal Number(s):
[40456]
Open Access
Abstract: We present the results of a resonant x-ray-diffraction experiment, resolving both charge and spin textures in the intermetallic topological magnet Euβ’(Al1βπ₯β’Gaπ₯)4 (π₯ = 0.1). Below β75 K the system develops a charge-density wave (CDW) with propagation vector π€CDWβ(0,0,0.18). The CDW order parameter grows monotonically on cooling until β15 K, when a sudden decrease in the CDW amplitude occurs. Pairs of magnetic satellites of the (0, 0, 8) Bragg reflection corresponding to two distinct domains, π€1 = (Β±πΏm, 0, 0), π€2 = (0, Β±πΏm, 0), πΏm=0.2002β’(4) were studied at the Eu πΏ3 edge, appearing below πN = 14.8 K. Our measurement of πN is exactly coincident with the sudden drop in the CDW amplitude, which suggests strong coupling between the charge and spin orders, as observed in other compounds of the Euβ’(Al1βπ₯β’Gaπ₯)4 series. Azimuthal measurements were consistent with a single helical spin arrangement having an elliptical envelope of πY/πZ = 1.19(6) for the π€2 domain, and a tilted helical (helicoidal) spin arrangement for the π€1 domain, with πY/πZ = 1.14(4) and πX/πZ = 0.20(2) that may be hidden for the π€2 domain due to multiple subdomains. Temperature evolution of the magnetic satellite intensities in linear and circularly polarized light found the respective ratio to be invariant with temperature, suggesting a single helicoidal magnetic phase throughout the measured temperature range. This behavior is unlike the π₯ = 0 material, in which a spin-density wave forms first, transitioning to a helical ground state on cooling through intermediate phases. Future theoretical work on the Eu electronic ground state, supported by related experiments, will help understand the effects of Ga substitution on the evolution of the magnetic structure.
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Aug 2026
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Yidian
Li
,
Mingxin
Zhang
,
Xian
Du
,
Cuiying
Pei
,
Jieyi
Liu
,
Houke
Chen
,
Wenxuan
Zhao
,
Kaiyi
Zhai
,
Yinqi
Hu
,
Senyao
Zhang
,
Jiawei
Shao
,
Mingxin
Mao
,
Yantao
Cao
,
Jinkui
Zhao
,
Zhengtai
Liu
,
Dawei
Shen
,
Yaobo
Huang
,
Makoto
Hashimoto
,
Donghui
Lu
,
Zhongkai
Liu
,
Yulin
Chen
,
Hanjie
Guo
,
Yilin
Wang
,
Yanpeng
Qi
,
Lexian
Yang
Abstract: The interplay among orbital-selective electron correlation, Hund's coupling, tunable structural motifs, and Kondo-like scattering establishes a compelling paradigm for understanding and engineering correlated multiorbital systems, as vividly exemplified by nickelate superconductors. Here, using high-resolution angle-resolved photoemission spectroscopy combined with theoretical calculations, we systematically investigate the electronic properties of trilayer nickelates. In La4β’Ni3β’O10, we observe pronounced interorbital hybridization, whereas in Pr4β‘Ni3β’O10, the flat ππ§2 band becomes markedly incoherent and diminishes in spectral weight. By contrast, the dispersive ππ₯2βπ¦2 bands retain coherence in both compounds. This striking incoherence/coherence dichotomy identifies an orbital differentiation modulated by the interlayer Ni-O-Ni bonding angle. The depletion of the ππ§2 orbitals further suppresses the interorbital hybridization and influences the density-wave transition in Pr4β‘Ni3β’O10. Moreover, the density-wave gap is substantially reduced in Pr4β‘Ni3β’O10, likely due to extra scattering channels provided by the local moments of Pβ’r3+ cations. Our findings reveal a structural control parameter for the multiorbital correlated state in trilayer nickelates, providing important insights into the emergence of superconductivity under high pressure.
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Aug 2026
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I05-ARPES
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S. K.
Mahatha
,
A.
Kar
,
J.
Corral-Sertal
,
J.
Diego
,
A.
Korshunov
,
C.-Y.
Lim
,
F. K.
Diekmann
,
D.
Subires
,
J.
Phillips
,
T. K.
Kim
,
D.
Ishikawa
,
G.
Marini
,
I.
Vobornik
,
I.
Errea
,
S.
Rohlf
,
M.
KallΓ€ne
,
V.
Bellini
,
A. Q. R.
Baron
,
Adolfo O.
Fumega
,
A.
Bosak
,
V.
Pardo
,
K.
Rossnagel
,
S.
Blanco-Canosa
Diamond Proposal Number(s):
[36505]
Abstract: First-order phase transitions, characterized by a discontinuous change in the order parameter, are intriguing phenomena in condensed matter physics. However, the underlying, material-specific, microscopic mechanisms often remain unclear. Here, we unveil a high-temperature incommensurate charge-order precursor with the wave vector πͺ*=(0,
1
4
+πΏ,
1
2
) in the 1T' phase of TaTe2, which competes with fluctuating high-temperature Ta trimer bonding states at πͺCO=(0,
1
3
,0). The precursor state follows the temperature dependence of the hidden incommensurability of the quasi-1D nested Fermi surface. In contrast, the low-temperature commensurate charge order at πͺCO, characterized by a charge disproportionation of the inequivalent Ta sites, appears to be driven by local chemical bonding. Dynamical lattice calculations identify an imaginary optical mode at πͺ*, involving an in-plane vibration of the Ta atoms forming a chainlike structure that renormalizes below πCO. Our experimental and theoretical observations suggest that the controversial first-order phase transition, as captured by phenomenological Ginzburg-Landau theory, results from the competition between two order parameters: one involving Fermi surface nesting and the other involving local chemical bonding.
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Jul 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 Ξ³ -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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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 π
β’Ti3β’Bi4 (π
=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 Ξ is identified as a surface state. The isotropic XAS profile of the π4,5 edge of the rare earth is consistent with the presence of the π
3+ oxidation state. Using the XMCD sum rules, backed by the atomic-multiplet-theory calculations, we obtain the spin and orbital magnetic moments. The Ti πΏ2,3-edge XMCD reveals the presence of a small magnetic moment in GdTi3β’Bi4, 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 π and π 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 π
β’Ti3β’Bi4 kagome metals.
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Jun 2026
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I21-Resonant Inelastic X-ray Scattering (RIXS)
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Diamond Proposal Number(s):
[24600, 30866]
Open Access
Abstract: The electron in a solid can be considered a bound state of the three independent, fundamental degrees of freedom creating quasiparticles: spinons, carrying the electron spin; plasmons, carrying the collective charge mode; and orbitons, carrying its orbital degree of freedom. These fundamental degrees of freedom could form ordering states in which dynamics or collective motions could occur and manifest as low-energy excitations. The exotic properties that appear in the materials exhibiting these electronic orderings are associated with these low-energy excitations. Although the orbital order (OO) and its coupling to the spin system creates very interesting phenomena, the microscopic origin of OO has been much less explored than other electronic properties as it is very difficult to directly access experimentally. Due to the recent improvement in energy resolution and flux, soft-x-ray resonant inelastic scattering (RIXS) allows for a reexamination of orbital excitations in manganites. Here, we present a study of low-energy excitations in half doped π΄-site ordered SmBaMn2β’O6 through a combination of RIXS and soft-x-ray resonant elastic scattering measurements. We confirm the existence of OO at πͺ = (0.25, 0.25, 0) and find various low-energy excitations below 200 meV. While several excitations can be assigned to be of magnetic and phononic origin, a group of excitations between 80 and 200 meV show a temperature dependence closely following that of the OO, making them possible candidates for orbitons.
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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-πc 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 πΏ3 edge to investigate the superconducting gap in the overdoped cuprate Bi2β’Sr2β’Ca2β’Cu3β’O10+πΏ (πcβ’=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 πc, indicative of superconducting-gap formation. This suppression is most pronounced at small momentum transfers [
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πβ₯
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β€0.18 r.l.u. (reciprocal lattice units)] and corresponds to a gap size of approximately 2β’Ξ0βΌ130 meV. Comparison with theoretical calculations of the momentum-dependent charge susceptibility supports a π-wave symmetry of the superconducting gap, while an isotropic π -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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Abstract: The Remeika stannides (π
3β’T4β’Sn13, 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 La3β’Co4β’Sn13 by conducting electrical transport measurements under uniaxial stress along different crystallographic directions ([100], [110], and [111]). We find that the superconducting transition temperature (πc) is suppressed under compression for all directions measured, in contrast to previous measurements under hydrostatic pressure. This indicates π -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 πc 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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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 (πβπ) 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 πHgHgβ‘(π) and pair distribution functions πHgHgβ‘(π)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 πHgHgβ‘(π) shifts to higher π, with the subsidiary peak at π=2β’πFexperiencing a concomitant shift consistent with the increased electron density. Considering the Evans π‘-matrix formulation of the Ziman theory of liquid metals, the structural πβ‘(2β’πF) 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 π-projected density of states towards the Fermi level is consistent with enhanced near-resonant π-electron scattering, and a corresponding increase in resistivity, analogous to the behavior of first-row transition metals. Analysis of the measured πHgHgβ‘(π) functions, and AIMD trajectories in real space, indicates that the liquid structure experiences a progressive development towards simple hard-sphere-like behavior at increasing πβπalong 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 πΏCDWβ0.23β0.35 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 πΏCDW. CDFs are present up to β300K and have relatively short correlation lengths of πβ20Γ
. Here we use Cu-πΏ3 and O-πΎ resonant inelastic x-ray scattering (RIXS) to study the doping dependence of CDW and CDFs in La2βπ₯β’Srπ₯β’CuO4. 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 πΏ4β’π-CDWβ0.24 and two CDF components with πΏ4β’π-CDFβ0.24 and πΏ3β’π-CDFβ0.30. We find that for πβππ the CDW coexists with the CDFs for dopings near π₯=πβ1/8. The 4β’π-CDW disappears beyond π₯=0.16 and the 4β’π-CDF beyond π₯=0.19, leaving only a weak 3β’π-CDF at the highest doping studied, π₯=0.22. Our data suggest that low-energy charge fluctuations exist up to doping π₯=0.19=πβ
, 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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