I06-Nanoscience (XPEEM)
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Gregg
Wildenberg
,
Kevin M.
Boergens
,
Lola
Lambert
,
Ruiyu
Li
,
Allison
Craig
,
Michael K. L.
Man
,
Amin
Moradi
,
Janek
Rieger
,
Hengli
Duan
,
Sarnjeet S.
Dhesi
,
Gabriel
Karras
,
Francesco
Maccherozzi
,
Keshav
Dani
,
Rudolf
Tromp
,
Sense Jan
Van Der Molen
,
Sarah B.
King
,
Narayanan
Kasthuri
Diamond Proposal Number(s):
[40333]
Open Access
Abstract: Photoemission electron microscopy (PEEM) offers a potential third modality for large-volume connectomics alongside transmission electron microscopy (TEM) and scanning electron microscopy (SEM). We image osmium stained, ultrathin brain sections on gold coated silicon at synaptic resolution using commercial PEEMs. At coarser resolution, we demonstrate that ultraviolet laser illumination enables gigavoxel-per-second acquisition rates without thermal damage. PEEM combines TEM-like parallel detection with SEM-compatible solid supports into a potentially scalable and cost-effective approach for large-volume connectomes.
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Nov 2025
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Emma
Van Der Minne
,
Priscila
Vensaus
,
Vadim
Ratovskii
,
Seenivasan
Hariharan
,
Jan
Behrends
,
Cesare
Franchini
,
Jonas
Fransson
,
Sarnjeet S.
Dhesi
,
Felix
Gunkel
,
Florian
Gossing
,
Georgios
Katsoukis
,
Ulrike I.
Kramm
,
Magalí
Lingenfelder
,
Qianqian
Lan
,
Yury V.
Kolen'Ko
,
Yang
Li
,
Ramsundar Rani
Mohan
,
Jeffrey
Mccord
,
Lingmei
Ni
,
Eva
Pavarini
,
Rossitza
Pentcheva
,
David H.
Waldeck
,
Michael
Verhage
,
Anke
Yu
,
Zhichuan J.
Xu
,
Piero
Torelli
,
Silvia
Mauri
,
Narcis
Avarvari
,
Anja
Bieberle-Hütter
,
Christoph
Baeumer
Open Access
Abstract: A central challenge in water electrolysis lies with the oxygen evolution reaction (OER) where the formation of molecular oxygen (O2) is hindered by the constraint of angular momentum conservation. While the reactants OH− or H2O are diamagnetic (DM), the O2 product has a paramagnetic (PM) triplet ground state, requiring a change in spin configuration when being formed. This constraint has prompted interest in spin-selective catalysts as a means to facilitate OER. In this context, the roles of magnetism and chirality-induced spin selectivity (CISS) in promoting the OER reaction have recently been investigated through both theoretical and experimental studies. However, pinpointing the key principles and their relative contribution in mediating spin-enhancement remains a significant challenge. This roadmap offers a forward-looking perspective on current experimental trends and theoretical developments in spin-enhanced OER electrocatalysis and outlines strategic directions for integrating incisive experiments and operando approaches with computational modeling to disentangle key mechanisms. By providing a conceptual framework and identifying critical knowledge gaps, this perspective aims to guide researchers toward dedicated experimental and computational studies that will deepen the understanding of spin-induced OER enhancement and accelerate the development of next-generation catalysts.
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Oct 2025
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I06-Nanoscience (XPEEM)
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Diamond Proposal Number(s):
[12893, 5888]
Open Access
Abstract: The elastic degree of freedom is widely exploited to mediate magnetoelectric coupling between ferromagnetic films and ferroelectric substrates. For epitaxial Fe films grown on clean BaTiO3 substrates, shear strain can determine the underlying magnetoelastic coupling. Here, we use PhotoEmission Electron Microscopy of ferroic Fe and BaTiO3 domains, combined with micromagnetic simulations, to directly reveal an inverted interfacial magnetoelastic coupling in the low-dimensional limit. We show that the magnetocrystalline anisotropy competes with the epitaxial shear strain to align the local magnetization of ultrathin Fe films close to the local polarization direction of the ferroelectric BaTiO3 in-plane domains. Poling the BaTiO3 substrate creates c-domains with no shear strain contribution with the local magnetization rotated by ~45°. Tuning shear strain magnetoelastic contributions suggests new routes for designing magnetoelectric devices.
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Sep 2025
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I06-Nanoscience (XPEEM)
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Massimo
Ghidini
,
Vladimir
Farenkov
,
Yang
Li
,
Peter J.
Newton
,
Raffaele
Pellicelli
,
Samer
Kurdi
,
Nadia A.
Stelmashenko
,
Francesco
Maccherozzi
,
Crispin H. W.
Barnes
,
Andrew F.
May
,
Manish
Chhowalla
,
Sarnjeet S.
Dhesi
,
Neil D.
Mathur
Diamond Proposal Number(s):
[31793]
Open Access
Abstract: Few-layer flakes of ferromagnetic Fe5–xGeTe2 with x = 0.3 (F5GT) possess a c-axis magnetocrystalline anisotropy that is large enough below ∼200 K to outcompete the easy-plane shape anisotropy, yielding distinctive magnetic microstructures with out-of-plane (OOP) magnetizations. Using photoemission electron microscopy (PEEM) with magnetic contrast from X-ray magnetic circular dichroism (XMCD) to study a thermally demagnetized h-BN-protected nanoflake of F5GT at 110 K, we observe a micron-scale coexistence between domains with OOP magnetizations (∼70% areal fraction) and hitherto unknown domains in which in-plane (IP) magnetization components dominate (∼30% areal fraction). The regions with dominant IP magnetization components do not correlate with small variations of flake thickness (6–10 nm) and instead arise from local changes of magnetocrystalline anisotropy due to a hitherto unidentified chemical inhomogeneity that we suggest to be a higher concentration of Fe vacancies. Our observation of micron-scale inhomogeneity would likely be missed if imaging a single flake orientation and should affect the viability and performance of van der Waals (vdW) spintronic devices with F5GT electrodes.
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Jul 2025
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I06-Nanoscience (XPEEM)
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Ian T.
Vidamour
,
Guru
Venkat
,
Charles
Swindells
,
David
Griffin
,
Paul W.
Fry
,
Richard M.
Rowan-Robinson
,
Alexander
Welbourne
,
Francesco
Maccherozzi
,
Sarnjeet S.
Dhesi
,
Susan
Stepney
,
Dan A.
Allwood
,
Thomas J.
Hayward
Open Access
Abstract: We describe “RingSim,” a phenomenological agent-based model that allows numerical simulation of magnetic nanowire networks with areas of hundreds of micrometers squared for durations of hundreds of seconds, a practical impossibility for general-purpose micromagnetic simulation tools. In RingSim, domain walls (DWs) are instanced as mobile agents, which respond to external magnetic fields, and their stochastic interactions with pinning sites and other DWs are described via simple phenomenological rules. We first present a detailed description of the model and its algorithmic implementation for simulating the behaviors of arrays of interconnected ring-shaped nanowires, which have previously been proposed as hardware platforms for unconventional computing applications. The model is then validated against a series of experimental measurements of an array’s static and dynamic responses to rotating magnetic fields. The robust agreement between the modeled and experimental data demonstrates that agent-based modeling is a powerful tool for exploring mesoscale magnetic devices, enabling time scales and device sizes that are inaccessible to more conventional magnetic simulation techniques.
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Apr 2025
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I06-Nanoscience (XPEEM)
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Diamond Proposal Number(s):
[32492]
Open Access
Abstract: The effect of thermal surface cleaning on the Gilbert damping (
) of yttrium iron garnet (YIG), before capping with a metallic layer, has been investigated. Our results show that
is strongly affected by relatively mild annealing conditions (T = 300 °C) when performed in a vacuum. This increase needs to be taken into account when obtaining the spin-mixing conductance from spin pumping measurements. We measure an increase in
by a factor of
8 when the YIG is vacuum annealed at 300 °C. No such changes in
are observed when annealed at the same temperature in 1
10−1 mbar of oxygen. We suggest that the main driver for the increase in
is the reduction of Fe3+ to Fe2+, as demonstrated by soft x-ray magnetic spectroscopy.
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Mar 2025
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I06-Nanoscience (XPEEM)
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Yu
Yan
,
Bo
Liu
,
Xianyang
Lu
,
Junlin
Wang
,
Sarnjeet S.
Dhesi
,
Iain G.
Will
,
Vlado K.
Lazarov
,
Jun
Du
,
Jing
Wu
,
Rong
Zhang
,
Yongbing
Xu
Abstract: Fe/GaAs is a prototype system of spin injection at room temperature. The interfacial strain and oriented bonds are both considered the origin of the Fe in-plane uniaxial magnetic anisotropy (UMA), which remains decisive. Here, by the x-ray magnetic circular dichroism (XMCD) and the vibrating sample magnetometer measurements, this study shows that in the Fe/Cr(t)/GaAs structure, the in-plane UMA of Fe originates from the chemical bonding between the Fe and the GaAs substrate by varying Cr thickness, t. The UMA drops as the Cr coverage increases, characterized by a decrease in the saturation field from 2400 to 57 Oe. The XMCD studies reveal that the Fe orbital moment, a signature of chemical bonds, decreases from 0.216 μB at Cr = 0 ML to 0.138 μB at Cr = 5 ML. The reduction of the Fe orbital moment and the UMA are qualitatively consistent, establishing a link between the UMA and the interfacial chemical bonds. The decreased UMA remains unchanged at t > 5 ML, above which Fe and GaAs are fully separated by a continuous Cr layer. Our findings provide clear experimental evidence that the UMA in the Fe/GaAs system originates from the oriented interface bonds, clarifying the UMA origin in this prototype system.
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Mar 2025
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I06-Nanoscience (XPEEM)
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O. J.
Amin
,
A.
Dal Din
,
E.
Golias
,
Y.
Niu
,
A.
Zakharov
,
S. C.
Fromage
,
C. J. B.
Fields
,
S. L.
Heywood
,
R. B.
Cousins
,
F.
Maccherozzi
,
J.
Krempasky
,
J. H.
Dil
,
D.
Kriegner
,
B.
Kiraly
,
R. P.
Campion
,
A. W.
Rushforth
,
K. W.
Edmonds
,
S. S.
Dhesi
,
L.
Šmejkal
,
T.
Jungwirth
,
P.
Wadley
Diamond Proposal Number(s):
[36317]
Open Access
Abstract: Nanoscale detection and control of the magnetic order underpins a spectrum of condensed-matter research and device functionalities involving magnetism. The key principle involved is the breaking of time-reversal symmetry, which in ferromagnets is generated by an internal magnetization. However, the presence of a net magnetization limits device scalability and compatibility with phases, such as superconductors and topological insulators. Recently, altermagnetism has been proposed as a solution to these restrictions, as it shares the enabling time-reversal-symmetry-breaking characteristic of ferromagnetism, combined with the antiferromagnetic-like vanishing net magnetization. So far, altermagnetic ordering has been inferred from spatially averaged probes. Here we demonstrate nanoscale imaging of altermagnetic states from 100-nanometre-scale vortices and domain walls to 10-micrometre-scale single-domain states in manganese telluride (MnTe). We combine the time-reversal-symmetry-breaking sensitivity of X-ray magnetic circular dichroism12 with magnetic linear dichroism and photoemission electron microscopy to achieve maps of the local altermagnetic ordering vector. A variety of spin configurations are imposed using microstructure patterning and thermal cycling in magnetic fields. The demonstrated detection and controlled formation of altermagnetic spin configurations paves the way for future experimental studies across the theoretically predicted research landscape of altermagnetism, including unconventional spin-polarization phenomena, the interplay of altermagnetism with superconducting and topological phases, and highly scalable digital and neuromorphic spintronic devices.
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Dec 2024
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I06-Nanoscience (XPEEM)
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Tuhin
Maity
,
Manisha
Bansal
,
Nives
Strkalj
,
Kapildeb
Dolui
,
Di
Zhang
,
Zihao
He
,
Guillaume F
Nataf
,
Adam
Lovett
,
Massimo
Ghidini
,
Sarnjeet S.
Dhesi
,
Ping
Lu
,
Haiyan
Wang
,
Weiwei
Li
,
Judith L.
Macmanus-Driscoll
Diamond Proposal Number(s):
[22427]
Open Access
Abstract: We investigate the emergence and optimization of conventional exchange bias (EB) in ultrathin (<10 nm) ferroelectric (FE) BaTiO3 (BTO)/ferromagnetic (FM) La0.67Sr0.33MnO3 (LSMO) epitaxial bilayers without an antiferromagnetic (AFM) material. The EB originates from the electronic orbital reconstruction at the FE-FM interface due to the ferroelectric polarization. We achieve maximum EB of approximately 42 Oe with single-domain polarization in nine-unit-cell-thick BTO, setting the BTO thickness above the critical threshold for ferroelectricity yet below the thickness of strain relaxation and multidomain breakdown. Furthermore, the LSMO layer needs to be thick enough to sustain both the FM layer and polarization-induced AFM spin configuration at the LSMO/BTO interface, yet as thin as possible to enable the EB loop shift. The temperature, training, field, and thickness dependence of the EB confirm that the LSMO/BTO interface exhibits conventional EB despite its unconventional origin. Using x-ray magnetic circular dichroism, scanning transmission electron microscopy, and density-functional-theory calculations, we confirm that the macroscopic EB effect originates from the interfacial AFM spin configuration in LSMO driven by FE-induced d-orbital modifications in interfacial Mn ions. Thus, we engineer strong interfacial EB coupling in artificial multiferroics without a conventional AFM material by controlling FE polarization, highlighting the potential for advanced spintronic applications.
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Nov 2024
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I06-Nanoscience (XPEEM)
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Alessandra
Milloch
,
Ignacio
Figueruelo-Campanero
,
Wei-Fan
Hsu
,
Selene
Mor
,
Simon
Mellaerts
,
Francesco
Maccherozzi
,
Larissa S. I.
Veiga
,
Sarnjeet S.
Dhesi
,
Mauro
Spera
,
Jin Won
Seo
,
Jean-Pierre
Locquet
,
Michele
Fabrizio
,
Mariela
Menghini
,
Claudio
Giannetti
Diamond Proposal Number(s):
[27218, 31711, 34455]
Open Access
Abstract: Avalanche resistive switching is the fundamental process that triggers the sudden change of the electrical properties in solid-state devices under the action of intense electric fields. Despite its relevance for information processing, ultrafast electronics, neuromorphic devices, resistive memories and brain-inspired computation, the nature of the local stochastic fluctuations that drive the formation of metallic regions within the insulating state has remained hidden. Here, using operando X-ray nano-imaging, we have captured the origin of resistive switching in a V2O3-based device under working conditions. V2O3 is a paradigmatic Mott material, which undergoes a first-order metal-to-insulator phase transition together with a lattice transformation that breaks the threefold rotational symmetry of the rhombohedral metallic phase. We reveal a new class of volatile electronic switching triggered by nanoscale topological defects appearing in the shear-strain based order parameter that describes the insulating phase. Our results pave the way to the use of strain engineering approaches to manipulate such topological defects and achieve the full dynamical control of the electronic Mott switching. Topology-driven, reversible electronic transitions are relevant across a broad range of quantum materials, comprising transition metal oxides, chalcogenides and kagome metals.
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Oct 2024
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