I11-High Resolution Powder Diffraction
|
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.
|
Oct 2026
|
|
I11-High Resolution Powder Diffraction
|
Liam A. V.
Nagle-Cocco
,
Joshua D.
Bocarsly
,
Krishnakanth
Sada
,
Nicola D.
Kelly
,
Mathias A.
Kiefer
,
Emmanuelle
Suard
,
Sarah J.
Day
,
Cheng
Liu
,
Clare P.
Grey
,
Prabeer
Barpanda
,
Clemens
Ritter
,
Sian E.
Dutton
Diamond Proposal Number(s):
[33664, 28349]
Open Access
Abstract: Cryptomelane is a hollandite-like material consisting of K+ cations in an α-MnO2 tunnel-like crystallographic motif. Cryptomelane with stoichiometry KxMn8O16 (x ≈ 1.45) has been synthesized and its magnetic properties investigated using variable-temperature magnetic susceptibility, heat capacity, and neutron powder diffraction. Three distinct transitions at T1 = 184 K, T2 = 54.5 K, and T3 = 24 K are observed. At T1 there is a subtle tetragonal → monoclinic transition associated with emergence of a set of nonmagnetic superstructure peaks indexable to a
incommensurate modulation parallel to the α-MnO2 tunnels. Our findings are consistent with a relation previously reported in titanate hollandites, that
. Magnetic Bragg peaks emerge below T2 = 54.5 K, and their positions indicate an incommensurate modulated magnetic structure. The model consistent with the data is a dual-
structure with a ferromagnetic
component and an incommensurate
, with the latter most likely to be helical. The period of oscillation of the incommensurate magnetic component is in line with predictions based on a Heisenberg spin Hamiltonian [Mandal et al. Phys. Rev. B 2014, 90, 104420]. Below T3 = 24 K, there is a magnetic transition, which gives rise to a different set of magnetic Bragg peaks indicative of a highly complex magnetic structure.
|
Oct 2026
|
|
|
|
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.
|
Sep 2026
|
|
I16-Materials and Magnetism
|
Aly H.
Abdeldaim
,
Rebecca
Scatena
,
James
Hawkins
,
Gareth
Nisbet
,
Daniel G.
Porter
,
Graeme
Barlow
,
Andy
Marshall
,
Brian
Nutter
,
Guillaume
Beutier
,
Stephen P.
Collins
,
Alessandro
Bombardi
Open Access
Abstract: Here, we review the capabilities of beamline I16 at Diamond Light Source after nearly 20 years of operation and continuous development. I16 is an X-ray scattering beamline operating in the 2.46–16 keV energy range with energy scans with a resolution of 1 meV. The beamline is equipped with a six-circle kappa diffractometer, offering flexible experimental geometries and support for a variety of ancillary equipment. Available equipment includes cryostats and cryofurnaces that span temperatures from 4.2 K to 700 K, which can be combined with applied electric fields, permanent magnets up to 1 T, and uniaxial strain cells. A range of detectors is mounted on the diffractometer arm, including a photon-counting area detector and an avalanche photodiode, both compatible with crystal analyzers for polarization analysis. Diamond single-crystal phase retarders provide full control of the incident X-ray polarization. These capabilities establish I16 as a state-of-the-art instrument for resonant and non-resonant X-ray scattering, multi Bragg coherent diffraction imaging, and grazing-incidence small- and wide-angle X-ray scattering. Together, they allow for studies of complex electronic, magnetic and structural phenomena in single crystals and thin films. We also outline the software infrastructure supporting experiment planning, data acquisition and rapid on-the-fly data analysis, and discuss ongoing developments and the anticipated benefits of the upgrade to a fourth-generation source.
|
Sep 2026
|
|
|
|
Open Access
Abstract: Equipping robots with a physical, brain-inspired computing unit is a key step towards achieving true autonomy in intelligent machines; however, the practical realization of such neuromorphic hardware remains a major challenge. Because both software- and hardware-based spiking neural network approaches demand substantial training and energy consumption, an architecturally simple neuromorphic platform is required to enable scalable and energy-efficient robotics. Here, we experimentally demonstrate robotic control driven by a neuromorphic hardware based on physical wave interactions. Using a water-based experimental system that provides direct visual access to wave-network dynamics, we establish a wave-based reservoir computing framework that achieves near-perfect accuracy in robotic vehicle obstacle recognition, followed by real-time autonomous motion with obstacle avoidance controlled entirely by this wave-based hardware. Through micromagnetic simulations, we extend this concept to electrically excited spin waves in a magnetic nanodevice operating at gigahertz frequencies, outlining an approach toward solid-state robotic chips based on wave computing. These results position wave-based computation as a scalable and energy-efficient alternative to conventional digital neuromorphic architectures for next-generation intelligent machines.
|
Sep 2026
|
|
I10-Beamline for Advanced Dichroism - scattering
|
Duncan
Miertschin
,
Sundar
Kunwar
,
Balaram
Regmi
,
Poshan
Kandel
,
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
,
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.
|
Sep 2026
|
|
I08-1-Soft X-ray Ptychography
|
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.
|
Sep 2026
|
|
|
|
M.
Ghidini
,
Sergio
Valencia
,
A.
Lesaine
,
R.
Mansell
,
V.
Farenkov
,
X.
Moya
,
N. A.
Stelmashenko
,
F.
Maccherozzi
,
C. W. H.
Barnes
,
F.
Kronast
,
S. S.
Dhesi
,
N. D.
Mathur
Open Access
Abstract: Voltage control of magnetic states in multiferroic heterostructures represents a promising route toward voltage-programmable magnetic devices. However, it remains challenging to achieve deterministic and non-volatile electrical control of well-defined magnetic states without the assistance of a magnetic field. Here we demonstrate repeatable and non-volatile voltage-driven interconversion between giant single-domain and multidomain magnetic states in a strain-coupled heterostructure comprising permalloy (Py) and 0.68Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 (011)pc (PMN-PT) (pc = pseudocubic). Growth-induced in-plane uniaxial magnetic anisotropy yields a square hysteresis loop, indicating a remanent monodomain state that is consistent with 15 µm-diameter XMCD-PEEM images. Low-voltage biasing of the PMN-PT substrate repeatably induces a ∼90° in-plane rotation of the magnetic easy axis and the concomitant formation of a multidomain state. At higher voltages, the easy axis rotates back to its original orientation, restoring the monodomain state. Cycling the ferroelectric substrate through minor loops near the coercive field yields non-volatile and repeatable switching between the multidomain and monodomain states. These results provide a pathway for voltage-programmable engineering of magnetic single-domain states in multiferroic heterostructures.
|
Aug 2026
|
|
|
|
Pratap
Pal
,
Xiaoxi
Deng
,
Gi‐yeop
Kim
,
Kyoungjun
Lee
,
Jheng-Cyuan
Lin
,
Prithwijit
Mandal
,
Jiangfeng
Yang
,
Paul
Steadman
,
Pascal
Manuel
,
Roger D.
Johnson
,
Si-Young
Choi
,
Paolo G.
Radaelli
,
Chang-Beom
Eom
Open Access
Abstract: The spin cycloid characteristic of noncollinear antiferromagnets offers significant potential for energy-efficient, magnon-mediated spintronic applications. Multiferroic BiFeO3 is among the most promising candidate materials because its antiferromagnetic order can be controlled by an electric field. However, in epitaxial BiFeO3 thin films, substrate clamping and epitaxial strain modify the cycloidal magnetic structure while limiting efficient ferroelastic-ferroelectric switching. Here, we show that strain-released freestanding BiFeO3 membranes overcome these limitations. Compared with substrate-clamped epitaxial thin films, a 100-nm-thick freestanding membrane exhibits ≈50% faster electric-field-driven ferroelectric switching and a spatially uniform, bulk-like single spin cycloid, as revealed by resonant elastic X-ray scattering. In contrast, the epitaxial thin film exhibits an expanded cycloid periodicity and slower ferroelectric switching dynamics, reflecting the influence of substrate-induced strain. Freestanding BiFeO3 membranes therefore overcome substrate-induced constraints by simultaneously restoring the intrinsic bulk-like spin cycloid and enabling substantially faster ferroelectric switching. This combination of robust noncollinear antiferromagnetic order and efficient electric-field switching establishes freestanding BiFeO3 membranes as a promising magnetoelectric platform for low-power magnonic and spintronic technologies, while enabling heterogeneous integration with Si-based devices.
|
Aug 2026
|
|
I10-Beamline for Advanced Dichroism - scattering
|
Diamond Proposal Number(s):
[38952]
Open Access
Abstract: High-entropy perovskite oxides offer a promising platform for tailoring magnetic functionality through compositional complexity; however, it remains unclear how targeted substitution of 4d transition metals modifies oxygen-mediated electronic structure and element-specific magnetic interactions. To address this question, we investigate the effect of Mo and Ru substitution on the electronic structure and magnetism of high-entropy perovskite oxide thin films using O K-edge and transition-metal L-edge X-ray absorption spectroscopy, X-ray magnetic circular dichroism (XMCD), and X-ray linear dichroism. O K-edge spectra reveal that Ru enhances O 2p–metal d hybridization, whereas Mo modifies charge distribution and local exchange pathways within the transition-metal sublattice. Multiplet analysis shows that Mn and Ni retain stable Mn4+ and Ni2+ states, while Co acts as the primary charge-compensation reservoir through changes in the Co2+/Co3+ ratio. Temperature-dependent XMCD demonstrates that these substitutions selectively reshape the magnetic exchange network, redistributing spin polarization among the constituent elements. Quantitative XMCD sum-rule analysis reveals that Mo substitution produces the highest reconstructed total magnetic moment across the measured temperature range, reaching values at low temperature that are nearly an order of magnitude larger than those observed in the Ru-containing compositions. These results establish a composition-driven strategy for tuning covalency, charge redistribution, and the balance between localized and itinerant magnetism in high-entropy oxide thin films, providing a pathway toward the design of tunable spintronic and multifunctional oxide materials.
|
Aug 2026
|
|
