I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[34243, 41066]
Open Access
Abstract: In
double perovskites (DPs) with 3d and 5d magnetic ions, the magnetic behavior of the B sublattice can be adjusted by selecting nonmagnetic isovalent
cations with d0 or d10 electron configuration. Here we show that
-site doping also enables magnetic tuning in 4f7 gadolinium DPs. We substitute Nb5+ (d0) for Sb5+ (d10) in the solid solution Ba2GdNbxSb1−xO6 (0 ≤ x ≤ 1) and find tunable local magnetic correlations evolving from weak antiferromagnetic (x = 0) to almost suppressed (x = 0.75) to minimal ferromagnetic (x = 1) interactions. We find that
-site doping tunes the superexchange between nearest-neighbor magnetic spins, enabling controlled suppression of the magnetic ordering temperature. In the x = 0.75 compound with almost no net magnetic interactions, we calculate a magnetocaloric effect with >99% of the maximum theoretical magnetic entropy for Heisenberg Gd3+ spins at 1.8 K and 9 T. This work demonstrates that
-site doping tunes magnetic interactions in
DPs, highlighting its potential for the rational design of efficient adiabatic demagnetization refrigeration (ADR) materials.
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Oct 2026
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I05-ARPES
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Cedric
Schmitt
,
Lukas
Gehrig
,
Kilian
Strauß
,
Jonas
Erhardt
,
Merit
Spring
,
Bing
Liu
,
Matthew D.
Watson
,
Han
Gao
,
Hanbo
Xiao
,
Zhongkai
Liu
,
Gang
Li
,
Giorgio
Sangiovanni
,
Jörg
Schäfer
,
Ralph
Claessen
,
Simon
Moser
Diamond Proposal Number(s):
[41909]
Abstract: Circular dichroism in angle-resolved photoemission spectroscopy (CD-ARPES) is widely used to probe orbital angular momentum (OAM) and Berry-curvature-related phenomena in two-dimensional quantum materials. However, in many materials, conventional micron-scale measurements often average over domains with opposite OAM polarization, canceling intrinsic dichroic signals and leaving spectra dominated by extrinsic asymmetries arising from photoelectron final-state interference. Here, we combine circularly polarized light with NanoARPES to achieve spatially resolved CD-ARPES with sub-800 nm resolution. By isolating individual domains, this approach enables direct access to the intrinsic OAM texture. As a model system, we investigate the K/K′ point valley states of the quantum spin Hall insulator indenene─a triangular indium monolayer epitaxially grown on SiC(0001)─where substrate-induced terraces host alternating valley configurations whose dichroic response is averaged out in conventional measurements. Terrace-resolved NanoARPES disentangles these contributions, allowing direct visualization of oppositely polarized domains and revealing the OAM texture associated with a topological band inversion. Our results establish spatially resolved CD-ARPES as a robust approach for isolating intrinsic OAM contrast by eliminating domain averaging and correcting for extrinsic geometry-dependent contributions. This enables direct access to the Berry curvature near the Fermi level, providing a powerful probe of the system’s intrinsic topological character.
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Oct 2026
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E02-JEM ARM 300CF
I15-Extreme Conditions
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Yizhe
Li
,
Ziqi
Yang
,
Ying
Chen
,
Zhenbo
Zhang
,
Yun-Long
Tang
,
Matthew
Smith
,
Matthew
Lindley
,
Xuezhen
Cao
,
Annette K.
Kleppe
,
Egor
Koemets
,
David G.
Hopkinson
,
Andrew J.
Bell
,
Steven J.
Milne
,
Antonio
Feteira
,
Sarah J.
Haigh
,
Alexander S.
Eggeman
,
Juncheng
Pan
,
Jiajun
Shi
,
Yuge
Yang
,
David A.
Hall
Diamond Proposal Number(s):
[32443, 36588]
Open Access
Abstract: Interfaces in oxide heterostructures act as critical regions to induce emergent and novel types of functionality in thin films. Herein, we demonstrate the creation of bulk ferroelectric heterostructures (BFHs) in monolithic ferroelectrics by nanoscale elemental partitioning, unlocking functionalities beyond the reach of conventional ferroelectrics and thin-film devices. The unique percolating, compositionally modulated networks act as built-in heterointerfaces that generate coupled ferroelectric-electrostatic-elastic fields, which stabilize charged domain walls and imprint predefined domain configurations throughout the bulk. In exemplar BiFeO3-BaTiO3 ceramics, the BFH approach raises the Curie temperature to 824°C (increment ΔTC > 350°C) and yields superior high-temperature piezoelectric responses (d33 > 400 picocoulombs per newton, k33 > 0.4), surpassing those of existing high-temperature piezoelectrics. Domain-engineered BFHs further unlock programmable control of domain switching, enabling the strongest yet tunable internal bias fields (>8 megavolts per meter) in bulk materials and record-high reversible shear electrostrains (up to 0.98%) at supercoercive field levels. The BFH design concept provides a transformative platform for next-generation ferroelectric and electromechanical transduction devices with extended temperature, high-power, and high-stress capability. It also establishes a universal framework for programmable control across ferroic families, including ferroelastic, ferromagnetic, and multiferroic materials in polycrystalline, single-crystal, and thin-film forms.
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Oct 2026
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Abstract: We present a comprehensive investigation of the layered vanadyl phosphate hydrates Ni(VO)2(PO4)2·4H2O (NiVP) and Co(VO)2(PO4)2·4H2O (CoVP), combining anisotropic magnetic susceptibility, heat capacity measurements, Density Functional Theory (DFT) calculations, and X-ray charge density analysis. Magnetization measurements reveal a ferromagnetic response along the crystallographic c-axis and an antiferromagnetic response within the ab-plane. Both compounds exhibit the presence of magnetocrystalline anisotropy, consistent with an easy-plane anisotropic magnetic state in NiVP, while in CoVP, strong spin–orbit coupling leads to a more complex behaviour that prevents a straightforward determination of the moment orientation. Prior to the onset of three-dimensional magnetic ordering at TN ≈ 4 K, both systems develop significant short-range spin correlations, as evidenced by deviations from the Curie–Weiss behaviour and a reduced λ-type anomaly in heat capacity, indicating a gradual crossover from low-dimensional correlations to three-dimensional ordering. DFT calculations consistently identify a ground state of columnar antiferromagnetic intralayer ordering and ferromagnetic interlayer coupling mediated by trimeric units. The exchange hierarchy indicates anisotropic intralayer interactions dominated by next-nearest-neighbour exchange, while interlayer coupling plays a leading role in establishing a three-dimensional order. Comparison between 3d orbital populations obtained from multipole model-refined experimental charge densities and DFT Mulliken analysis shows good agreement, validating the electronic structure description. The results highlight the importance of orbital polarization in establishing different superexchange pathways through phosphate groups, with interlayer coupling primarily governed by σ-type interactions and intralayer exchange involving π-mediated interactions, mediated by the molecular orbital of the bridging phosphate group between the metal centers.
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Sep 2026
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I08-1-Soft X-ray Ptychography
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Diamond Proposal Number(s):
[30417]
Open Access
Abstract: Compensated magnets are of increasing interest for both fundamental research and applications, with their net-zero magnetization leading to ultrafast dynamics and robust order. To understand and control this order, nanoscale mapping of local domain structures is necessary. One of the main routes to mapping antiferromagnetic order is x-ray magnetic linear dichroism (XMLD), which probes the local orientation of the Néel vector. However, XMLD imaging typically suffers from weak contrast and has mainly been limited to surface-sensitive techniques. Here, we harness coherent diffractive imaging to map the complex XMLD spectroscopically, and identify the phase linear dichroism as a high-contrast, high-resolution mechanism for imaging magnetic order. By applying x-ray spectroptychography to a model sample, we retrieve the full complex XMLD spectrum. Combining this with hierarchical clustering, we resolve the spatial distribution of probed domains by their distinct spectral signatures, providing a robust method for analyzing magnetic configurations with weak signals. Our results show that phase contrast is significantly stronger than the corresponding absorption contrast, offering higher spatial-resolution magnetic imaging. This approach establishes a reliable element- and orbital-sensitive tool for studying compensated magnets.
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Sep 2026
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Yong-Zhen
Jiang
,
Qi‐xun
Wen
,
Xiang
Xu
,
Su-Tao
Sun
,
Feng-Fan
Ren
,
Zi-Xuan
Zhou
,
Xing-Yuan
You
,
Yu-Cheng
Kan
,
Zheng
Zhang
,
Jie-Yi
Liu
,
Yu-Zhou
Zhao
,
Zheng-Tai
Liu
,
Mao
Ye
,
Shu-Hua
Yao
,
Jian
Zhou
,
Yan-Bin
Chen
,
Zhong-Kai
Liu
,
Yu-Lin
Chen
,
Yang‐yang
Lv
,
Cheng
Chen
Open Access
Abstract: Bismuth oxyselenide (Bi2O2Se) has emerged as a leading semiconductor candidate for next-generation electronics and quantum phenomena research. However, its strong ionic interlayer bonding of Se layers fundamentally restricts the full potential of this otherwise promising quasi-two-dimensional (2D) material. In this work, we demonstrate chlorine substitution as an effective strategy to introduce van der Waals gaps and modify the electronic structure of the system. Through comprehensive transport and angle-resolved photoemission spectroscopy (ARPES) measurements on Bi6O6Se2Cl2 single crystal, an optimal Cl-doping compound, we show that the key electronic features, including indirect bandgap, high electron mobility, and carrier effective mass, are well preserved, while the 2D character of the system is sufficiently enhanced. First-principles calculations attribute this selective tunability to the unique spatial separation between conductive Bi-O layers and dopant Se/Cl layers, which enables independent optimization of interlayer coupling and intralayer transport. Remarkably, our theoretical calculations combined with experimental observations project a broad bandgap engineering across a wide range (0.8 ∼ 3.5 eV) within the Bi2O2Se system. Our findings not only expand the application potential of Bi2O2Se-based materials in optoelectronics, nanoelectronics, and fundamental research but also highlight spatial decoupling as a viable strategy for modifying the detailed electronic structure of quasi-2D quantum systems.
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Sep 2026
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I05-ARPES
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Wanying
Chen
,
Hongyun
Zhang
,
Jinxi
Lu
,
Yu
Gu
,
Qiyun
Xu
,
Fei
Wang
,
Xuanxi
Cai
,
Jiansong
Li
,
Jiayong
Xiao
,
Rui
Chen
,
Kenji
Watanabe
,
Takashi
Taniguchi
,
Jose
Avila
,
Pavel
Dudin
,
Matthew D.
Watson
,
Pu
Yu
,
Shengwei
Jiang
,
Wenhui
Duan
,
Tingxin
Li
,
Chong
Wang
,
Shuyun
Zhou
Diamond Proposal Number(s):
[39762]
Abstract: Twisted MoTe2 hosts intriguing correlated quantum phenomena including the fractional quantum anomalous Hall effect in twisted bilayer (t-BL) MoTe2 near 3.7°, which is sensitive to the twist angle and moiré superlattices. Here, we directly visualize the twist-angle-modulated electronic structure of t-BL and twisted double-bilayer (t-DBL) MoTe2 near this critical angle. We find that the moiré superlattice not only modifies the relative energy between the Γ and 𝐾 valleys in t-BL MoTe2, but also strongly reconstructs the Γ valley for both t-BL and t-DBL MoTe2. Specifically, the deep 𝑝𝑧-derived band at Γ exhibits a distinct splitting that systematically varies with increasing twist angle. Theoretical analysis suggests that this modulation arises from the twist-angle-dependent lattice relaxation, especially interfacial corrugations. Our work directly visualizes the moiré-modulated electronic structure and provides key spectroscopic information of lattice relaxation and interlayer interactions underlying the physics of twisted MoTe2.
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Sep 2026
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I05-ARPES
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Gianmarco
Gatti
,
Amalie H.
Svaneborg
,
Wu
Bing
,
Gesa-R.
Siemann
,
Anders S.
Mortensen
,
Naina
Kushwaha
,
Jennifer
Rigden
,
Jakob K.
Svaneborg
,
Matthew D.
Watson
,
Timur K.
Kim
,
Charlotte
Sanders
,
Kristian S.
Thygesen
,
Zdenek
Sofer
,
Philip
Hofmann
Diamond Proposal Number(s):
[39998]
Abstract: The bulk and surface electronic structure of MoAlB(010) is studied by a combination of angle-resolved photoemission spectroscopy and density functional calculations. The observed bulk Fermi-level crossings agree with the previously reported bulk Fermi surface of the material. Additionally, we find several surface states in the wide projected bulk band gaps around the Fermi energy. The surface states differ in their stability under residual-gas exposure in the vacuum system and in the magnitude of their Rashba-type spin-orbit splitting. We explain this in terms of their elemental and orbital character. A surface state arising from Al dangling bonds is sensitive to surface contamination, whereas a mainly Mo-derived surface state exhibits the stronger spin-orbit splitting.
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Sep 2026
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I10-Beamline for Advanced Dichroism - scattering
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Duncan
Miertschin
,
Sundar
Kunwar
,
Balaram
Regmi
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Poshan
Kandel
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Sanjib
Thapa
,
Davis
Crater
,
Luca
Basso
,
Adam
Dodson
,
Zheng
Gai
,
Lide
Yao
,
Yu-Wei
Chen
,
Peter
Bencok
,
Armin
Kleibert
,
Yen-Lin
Huang
,
Andy
Mounce
,
Paul G.
Kotula
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Sebastiaan
Van Dijken
,
Alessandro R.
Mazza
,
Thomas Z.
Ward
,
Nick
Shepelin
,
Alan
Farhan
Diamond Proposal Number(s):
[40992]
Open Access
Abstract: Multiferroics that combine ferroelectricity and magnetic order are attractive for electronic and spintronic technologies, yet chemical disorder that promotes relaxor ferroelectricity usually suppresses long-range magnetic order. Here, we report entropy-stabilized relaxor multiferroicity in epitaxial hexagonal (Tb0.2Dy0.2Ho0.2Lu0.2Yb0.2)FeO3 thin films. Structural, magnetic, dielectric, and synchrotron spectroscopic measurements show the coexistence of relaxor ferroelectricity and long-range ferromagnetic order. We find that improper ferroelectricity remains robust against A-site configurational disorder, while the Fe sublattice preserves magnetic exchange. This separation of the microscopic origins of the polar and magnetic responses enables chemically disordered multiferroicity. Our results establish entropy engineering in hexagonal ferrites as a route toward multifunctional oxide thin films and provide a general design strategy for high-entropy multiferroics.
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Sep 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[7758, 8615]
Open Access
Abstract: The β′-Gd2(MoO4)3 phase is one of the most well-known multiferroic materials, exhibiting both ferroelectricity and ferroelasticity under ambient conditions, with a complex temperature-pressure phase diagram. In this study, we review the pressure-dependent behavior of the RE2(MoO4)3 compound family (where RE ≡ Pr–Ho), which crystallizes in the β′-phase, with the β-phase being the paraelectric parent structure. Eu, Tb, and Ho molybdates were synthesized via solid-state reactions, ensuring the absence of impurities. High-pressure experiments at DIAMOND synchrotron revealed that the β′-phase persists at low-pressures. At approximately 2 GPa, new peaks emerged, which were refined as a mixture of the β′-phase, other rare-earth molybdates, and oxides, some of which have been detected in earlier stages of synthesis. The β′-phase became distorted with increasing pressure while coexisting with these new phases, whose average unit cell volume was found to lie between that of the β′-phase and the formed distorted phase. Ultimately, this multiphase crystalline decomposition acts as a precursor to pressure-induced amorphization, leading to a loss of long-range periodicity without complete loss of local order. The onsets of pressure-induced decomposition, distortion of the β′-phase and apparent amorphization increase as the ionic radius of the rare-earth element decreases. This scenario of irreversible structural disorder accumulated through phase coexistence is consistent with previous studies and resolves a debate persisting for over half a century.
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Aug 2026
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