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117 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I10-Beamline for Advanced Dichroism	Electron beam lithography of magnetic skyrmions Yao Guang , Yong Peng , Zhengren Yan , Yizhou Liu , Junwei Zhang , Xue Zeng , Senfu Zhang , Shilei Zhang , David M. Burn , Nicolas Jaouen , Jinwu Wei , Hongjun Xu , Jiafeng Feng , Chi Fang , Gerrit Van Der Laan , Thorsten Hesjedal , Baoshan Cui , Xixiang Zhang , Guoqiang Yu , Xiufeng Han Advanced Materials DOI: 10.1002/adma.202003003 Diamond Proposal Number(s): [20183, 21868] Show Abstract ▼ Abstract: The emergence of magnetic skyrmions, topological spin textures, has aroused tremendous interest in studying the rich physics related to their topology. While skyrmions promise high‐density and energy‐efficient magnetic memory devices for information technology, the manifestation of their nontrivial topology through single skyrmions and ordered and disordered skyrmion lattices could also give rise to many fascinating physical phenomena, such as chiral magnon and skyrmion glass states. Therefore, generating skyrmions at designated locations on a large scale, while controlling the skyrmion patterns, is the key to advancing topological magnetism. Here, a new, yet general, approach to the “printing” of skyrmions with zero‐field stability in arbitrary patterns on a massive scale in exchange‐biased magnetic multilayers is presented. By exploiting the fact that the antiferromagnetic order can be reconfigured by local thermal excitations, a focused electron beam with a graphic pattern generator to “print” skyrmions is used, which is referred to as skyrmion lithography. This work provides a route to design arbitrary skyrmion patterns, thereby establishing the foundation for further exploration of topological magnetism.	Aug 2020
I10-Beamline for Advanced Dichroism	Direct observation of ferrimagnetic ordering in inverse Heusler alloy Mn 2 CoAl Zhendong Chen , Wenqing Liu , Peng Chen , Xuezhong Ruan , Jiabao Sun , Ruobai Liu , Cunxu Gao , Jun Du , Bo Liu , Hao Meng , Rong Zhang , Yongbing Xu Applied Physics Letters 117 DOI: 10.1063/5.0013656 Diamond Proposal Number(s): [22532] Show Abstract ▼ Abstract: Compensated ferrimagnetic Heusler compounds with high spin polarization and a low net magnetic moment are strategically important materials for spin-logic and further energy-efficient spintronic applications. However, the element-resolved magnetic ordering of these compensated ferrimagnets remains an open issue. Here, we report a direct observation of the spin and orbital moments of the B2 phase Mn2CoAl thin film using the synchrotron-based x-ray magnetic circular dichroism technique. An ferrimagnetic ordering between Mn and Co elements and a compensated-ferrimagnet-like small net magnetic moment of only 0.34 μB/f.u. were observed unambiguously in B2 Mn2CoAl. Antiparallel coupling between Mn and Co is attributed to the mixture of the Mn(B) and Al occupation in the B2 phase Mn2CoAl lattice. This work demonstrates great potential of the compensated ferrimagnetic half-metallic inverse Heusler compounds Mn2CoAl for spintronic applications.	Jul 2020
I10-Beamline for Advanced Dichroism	Quenching and restoration of orbital angular momentum through a dynamic bond in a cobalt(II) complex Sheng-qun Su , Shu-qi Wu , Michael L. Baker , Peter Bencok , Nobuaki Azuma , Yuji Miyazaki , Motohiro Nakano , Soonchul Kang , Yoshihito Shiota , Kazunari Yoshizawa , Shinji Kanegawa , Osamu Sato Journal Of The American Chemical Society DOI: 10.1021/jacs.0c02257 Diamond Proposal Number(s): [17723] Show Abstract ▼ Abstract: Orbital angular momentum plays a vital role in various applications, especially magnetic and spintronic properties. There-fore, controlling orbital angular momentum is of paramount importance to both fundamental science and new technologi-cal applications. Many attempts have been made to modulate the ligand-field induced quenching effects of orbital angular momentum to manipulate magnetic properties. However, to date, reported changes in the magnitude of orbital angular momentum are small in both molecular and solid-state magnetic materials. Moreover, no effective methods currently exist to modulate orbital angular momentum. Here, we report a dynamic bond approach to realize a large change in orbital angu-lar momentum. We have developed a Co(II) complex that exhibits coordination number switching between six and seven. This cooperative dynamic bond switching induces considerable modulation of the ligand field, thereby leading to substantial quenching and restoration of the orbital angular momentum. This switching mechanism is entirely different from those of spin-crossover and valence tautomeric compounds, which exhibit switching in spin multiplicity.	Jun 2020
I08-Scanning X-ray Microscopy beamline (SXM) I10-Beamline for Advanced Dichroism	Iron stored in ferritin is chemically reduced in the presence of aggregating Aβ(1-42) James Everett , Jake Brooks , Frederik Lermyte , Peter B. O’connor , Peter J. Sadler , Jon Dobson , Joanna F. Collingwood , Neil D. Telling Scientific Reports 10 DOI: 10.1038/s41598-020-67117-z Open Access Show Abstract ▼ Abstract: Atypical low-oxidation-state iron phases in Alzheimer’s disease (AD) pathology are implicated in disease pathogenesis, as they may promote elevated redox activity and convey toxicity. However, the origin of low-oxidation-state iron and the pathways responsible for its formation and evolution remain unresolved. Here we investigate the interaction of the AD peptide β-amyloid (Aβ) with the iron storage protein ferritin, to establish whether interactions between these two species are a potential source of low-oxidation-state iron in AD. Using X-ray spectromicroscopy and electron microscopy we found that the co-aggregation of Aβ and ferritin resulted in the conversion of ferritin’s inert ferric core into more reactive low-oxidation-states. Such findings strongly implicate Aβ in the altered iron handling and increased oxidative stress observed in AD pathogenesis. These amyloid-associated iron phases have biomarker potential to assist with disease diagnosis and staging, and may act as targets for therapies designed to lower oxidative stress in AD tissue.	Jun 2020
I10-Beamline for Advanced Dichroism	Van der Waals epitaxy of ultrathin early transition metal (Ti & V) (di)selenides: charge and magnetic order in the ultrathin limit Manuel Bonilla Lopez Show Abstract ▼ Abstract: Since the isolation of graphene in 2004, two-dimensional (2D) layered materials, specially the transition metal dichalcogenides (TMDs), have attracted immense interest from theoreticians and experimentalist due to the diversity of properties presented in this family of materials. The main reason for the interest in such materials has been the observation of emergent properties as a consequence of the reduced dimensions, i.e. the monolayer regime. Initially the monolayer regime was obtained via the scotch-tape method. The implementation of exfoliation techniques was successful since layered 2D materials are composed of stacked layers held together by weak van der Walls forces that permits separations of the layers and therefore reducing the material dimensions. Despite this, exfoliation techniques have limitations as they are not as successful in obtaining thin forms of certain TMDs as it was done in graphite to obtain graphene. Some TMDs might react to the ambient in which the exfoliation is done impeding the obtention of pristine thin samples. By now, there are different ways to reach the monolayers regimes that allow synthetizing monolayer forms of TMDs that were not obtained via exfoliation methods. This dissertation implements molecular beam epitaxy (MBE), an ultra-high vacuum deposition method that provides a clean environment for layer-by-layer synthesis of TMD materials.	Jun 2020
I05-ARPES I10-Beamline for Advanced Dichroism	Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe3 Matthew D. Watson , Igor Markovic , Federico Mazzola , Akhil Rajan , Edgar A. Morales , David Burn , Thorsten Hesjedal , Gerrit Van Der Laan , Saumya Mukherjee , Timur K. Kim , Chiara Bigi , Ivana Vobornik , Monica Ciomaga Hatnean , Geetha Balakrishnan , Philip D. C. King Physical Review B 101 DOI: 10.1103/PhysRevB.101.205125 Diamond Proposal Number(s): [21986, 22794, 23785] Show Abstract ▼ Abstract: We investigate the temperature-dependent electronic structure of the van der Waals ferromagnet, CrGeTe3. Using angle-resolved photoemission spectroscopy, we identify atomic- and orbital-specific band shifts upon cooling through TC. From these, together with x-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements, we identify the states created by a covalent bond between the Te 5p and the Cr eg orbitals as the primary driver of the ferromagnetic ordering in this system, while it is the Cr t2g states that carry the majority of the spin moment. The t2g states furthermore exhibit a marked bandwidth increase and a remarkable lifetime enhancement upon entering the ordered phase, pointing to a delicate interplay between localized and itinerant states in this family of layered ferromagnets.	May 2020
I10-Beamline for Advanced Dichroism	Coherent transfer of spin angular momentum by evanescent spin waves within antiferromagnetic NiO Maciej Dabrowski , Takafumi Nakano , David Burn , Andreas Frisk , David G. Newman , Christoph Klewe , Qian Li , Mengmeng Yang , Padraic Shafer , Elke Arenholz , Thorsten Hesjedal , Gerrit Van Der Laan , Zi Q. Qiu , Robert J. Hicken Physical Review Letters 124, 217201 DOI: 10.1103/PhysRevLett.124.217201 Diamond Proposal Number(s): [17745, 19116, 20760] Show Abstract ▼ Abstract: Insulating antiferromagnets have recently emerged as efficient and robust conductors of spin current. Element-specific and phase-resolved x-ray ferromagnetic resonance has been used to probe the injection and transmission of ac spin current through thin epitaxial NiO(001) layers. The spin current is found to be mediated by coherent evanescent spin waves of GHz frequency, rather than propagating magnons of THz frequency, paving the way towards coherent control of the phase and amplitude of spin currents within an antiferromagnetic insulator at room temperature.	May 2020
I10-Beamline for Advanced Dichroism	Macroscopic polarization change via electron transfer in a valence tautomeric cobalt complex Shu-qi Wu , Meijiao Liu , Kaige Gao , Shinji Kanegawa , Yusuke Horie , Genki Aoyama , Hajime Okajima , Akira Sakamoto , Michael L. Baker , Myron S. Huzan , Peter Bencok , Tsukasa Abe , Yoshihito Shiota , Kazunari Yoshizawa , Wenhuang Xu , Hui-zhong Kou , Osamu Sato Nature Communications 11 DOI: 10.1038/s41467-020-15988-1 Diamond Proposal Number(s): [21117] Open Access Show Abstract ▼ Abstract: Polarization change induced by directional electron transfer attracts considerable attention owing to its fast switching rate and potential light control. Here, we investigate electronic pyroelectricity in the crystal of a mononuclear complex, [Co(phendiox)(rac-cth)](ClO4)·0.5EtOH (1·0.5EtOH, H2phendiox = 9, 10-dihydroxyphenanthrene, rac-cth = racemic 5, 5, 7, 12, 12, 14-hexamethyl-1, 4, 8, 11-tetraazacyclotetradecane), which undergoes a two-step valence tautomerism (VT). Correspondingly, pyroelectric current exhibits double peaks in the same temperature domain with the polarization change consistent with the change in dipole moments during the VT process. Time-resolved Infrared (IR) spectroscopy shows that the photo-induced metastable state can be generated within 150 ps at 190 K. Such state can be trapped for tens of minutes at 7 K, showing that photo-induced polarization change can be realized in this system. These results directly demonstrate that a change in the molecular dipole moments induced by intramolecular electron transfer can introduce a macroscopic polarization change in VT compounds.	Apr 2020
I10-Beamline for Advanced Dichroism	Real-space imaging of confined magnetic skyrmion tubes M. T. Birch , D. Cortés-ortuño , L. A. Turnbull , M. N. Wilson , F. Groß , N. Träger , A. Laurenson , N. Bukin , S. H. Moody , M. Weigand , G. Schütz , H. Popescu , R. Fan , P. Steadman , J. A. T. Verezhak , G. Balakrishnan , J. C. Loudon , A. C. Twitchett-harrison , O. Hovorka , H. Fangohr , F. Y. Ogrin , J. Gräfe , P. D. Hatton Nature Communications 11 DOI: 10.1038/s41467-020-15474-8 Diamond Proposal Number(s): [20866] Open Access Show Abstract ▼ Abstract: Magnetic skyrmions are topologically nontrivial particles with a potential application as information elements in future spintronic device architectures. While they are commonly portrayed as two dimensional objects, in reality magnetic skyrmions are thought to exist as elongated, tube-like objects extending through the thickness of the host material. The study of this skyrmion tube state (SkT) is vital for furthering the understanding of skyrmion formation and dynamics for future applications. However, direct experimental imaging of skyrmion tubes has yet to be reported. Here, we demonstrate the real-space observation of skyrmion tubes in a lamella of FeGe using resonant magnetic x-ray imaging and comparative micromagnetic simulations, confirming their extended structure. The formation of these structures at the edge of the sample highlights the importance of confinement and edge effects in the stabilisation of the SkT state, opening the door to further investigation into this unexplored dimension of the skyrmion spin texture.	Apr 2020
I10-Beamline for Advanced Dichroism	Element- and time-resolved measurements of spin dynamics using X-ray detected ferromagnetic resonance Christoph Klewe , Qian Li , Mengmeng Yang , Alpha T. N’diaye , David M. Burn , Thorsten Hesjedal , Adriana Figueroa , Chanyong Hwang , Jia Li , Robert J. Hicken , Padraic Shafer , Elke Arenholz , Gerrit Van Der Laan , Ziqiang Qiu Synchrotron Radiation News 33:2, 12 - 19 DOI: 10.1080/08940886.2020.1725796 Diamond Proposal Number(s): [18542, 19116, 20483, 20493, 21616]	Apr 2020

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