Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

254 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	Depth profiling of 3D skyrmion lattices in a chiral magnet—A story with a twist Gerrit Van Der Laan , S. L. Zhang , T. Hesjedal Aip Advances 11 DOI: 10.1063/9.0000072 Diamond Proposal Number(s): [11784, 12943, 12958] Open Access Show Abstract ▼ Abstract: From the perspective of surface science, only the topmost atomic layers usually exhibit physical properties that are different to those of the bulk material, whereas the deeper layers are assumed to be bulk-like and remain largely unexplored. Going beyond conventional diffraction and imaging techniques, we have determined the depth dependence of the full 3D spin structure of magnetic skyrmions below the surface of a bulk Cu2OSeO3 sample using the polarization dependence of resonant elastic x-ray scattering (REXS). While the bulk spin configuration showed the anticipated Bloch type structure, it was found that the skyrmion lattice changes to a Néel twisting (i.e., with a different helicity angle) at the surface within a distance of several hundred nm. The exact surface helicity angle and penetration length of this twist have been determined, revealing the detailed internal structure of the skyrmion tube. It was found that the experimental penetration length of the Néel twisting is 7× longer than the theoretical value given by the ratio of J/D. This indicates that apart from the considered spin interactions, i.e., the Heisenberg exchange interaction J and the Dzyaloshinskii-Moriya interaction D, as well as the Zeeman interaction, other effects must play an important role. The findings suggest that the surface reconstruction of the skyrmion lattice is a universal phenomenon, stemming from the breaking of translational symmetry at the interface.	Jan 2021
I10-Beamline for Advanced Dichroism	Creation of a chiral bobber lattice in helimagnet-multilayer heterostructures Kejing Ran , Yizhou Liu , Yao Guang , David M. Burn , Gerrit Van Der Laan , Thorsten Hesjedal , Haifeng Du , Guoqiang Yu , Shilei Zhang Physical Review Letters 126 DOI: 10.1103/PhysRevLett.126.017204 Diamond Proposal Number(s): [20182] Open Access Show Abstract ▼ Abstract: A chiral bobber is a localized three-dimensional magnetization configuration, terminated by a singularity. Chiral bobbers coexist with magnetic skyrmions in chiral magnets, lending themselves to new types of skyrmion-complementary bits of information. However, the on-demand creation of bobbers, as well as their direct observation remained elusive. Here, we introduce a new mechanism for creating a stable chiral bobber lattice state via the proximity of two skyrmion species with comparable size. This effect is experimentally demonstrated in a Cu 2 OSeO 3 / [ Ta / CoFeB / MgO ] 4 heterostructure in which an exotic bobber lattice state emerges in the phase diagram of Cu 2 OSeO 3 . To unambiguously reveal the existence of the chiral bobber lattice state, we have developed a novel characterization technique, magnetic truncation rod analysis, which is based on resonant elastic x-ray scattering.	Jan 2021
I10-Beamline for Advanced Dichroism	Magnetization dynamics in ordered spin structures revealed by diffractive and reflectometry ferromagnetic resonance D. M. Burn , S. L. Zhang , Gerrit Van Der Laan , T. Hesjedal Aip Advances 11 DOI: 10.1063/9.0000058 Diamond Proposal Number(s): [18898, 23895] Open Access Show Abstract ▼ Abstract: Synchrotron radiation based techniques provide unique insight into both the element and time resolved magnetization behavior in magnetic spin systems. Here, we highlight the power of two recent developments, utilizing x-ray scattering techniques to reveal the precessional magnetization dynamics of ordered spin structures in the GHz regime, both in diffraction and reflection configurations. Our recently developed diffraction and reflectometry ferromagnetic resonance (DFMR and RFMR) techniques provide novel ways to explore the dynamics of modern magnetic materials, thereby opening up new pathways for the development of spintronic devices. In this paper we provide an overview of these techniques, and discuss the new understanding they provide into the magnetization dynamics in the chiral magnetic structure in Y-type hexaferrite and the depth dependence to the magnetization dynamics in a [CoFeB/MgO/Ta]4 multilayer.	Jan 2021
	Absence of magnetic proximity effect at the interface of Bi2Se3 and (Bi,Sb)2Te3 with EuS A. I. Figueroa , F. Bonell , M. G. Cuxart , M. Valvidares , P. Gargiani , G. Van Der Laan , A. Mugarza , S. O. Valenzuela Physical Review Letters 125, 226801 DOI: 10.1103/PhysRevLett.125.226801 Show Abstract ▼ Abstract: We performed x-ray magnetic circular dichroism (XMCD) measurements on heterostructures comprising topological insulators (TIs) of the (Bi,Sb)2(Se,Te)3 family and the magnetic insulator EuS. XMCD measurements allow us to investigate element-selective magnetic proximity effects at the very TI/EuS interface. A systematic analysis reveals that there is neither significant induced magnetism within the TI nor an enhancement of the Eu magnetic moment at such interface. The induced magnetic moments in Bi, Sb, Te, and Se sites are lower than the estimated detection limit of the XMCD measurements of ∼10−3 μB/at.	Nov 2020
I10-Beamline for Advanced Dichroism	Optically and microwave-induced magnetization precession in [Co/Pt]/NiFe exchange springs Maciej Dabrowski , Andreas Frisk , David M. Burn , David G. Newman , Christoph Klewe , Alpha T. N’diaye , Padraic Shafer , Elke Arenholz , Graham J. Bowden , Thorsten Hesjedal , Gerrit Van Der Laan , Gino Hrkac , Robert J. Hicken Acs Applied Materials & Interfaces DOI: 10.1021/acsami.0c14058 Diamond Proposal Number(s): [17745, 19116, 20760] Show Abstract ▼ Abstract: Microwave and heat-assisted magnetic recordings are two competing technologies that have greatly increased the capacity of hard disk drives. The efficiency of the magnetic recording process can be further improved by employing non-collinear spin structures that combine perpendicular and in-plane magnetic anisotropy. Here, we investigate both microwave and optically excited magnetization dynamics in [Co/Pt]/NiFe exchange spring samples. The resulting canted magnetization within the nanoscale [Co/Pt]/NiFe interfacial region allows for optically stimulated magnetization precession to be observed for an extended magnetic field and frequency range. The results can be explained by formation of an imprinted domain structure, which locks the magnetization orientation and makes the structures more robust against external perturbations. Tuning the canted interfacial domain structure may provide greater control of optically excited magnetization reversal and optically generated spin currents, which are of paramount importance for future ultrafast magnetic recording and spintronic applications.	Nov 2020
I21-Resonant Inelastic X-ray Scattering (RIXS)	Resonant inelastic x-ray spectroscopy on UO$_{2}$ as a test case for actinide materials G. H. Lander , Martin Sundermann , Ross Springell , Andrew Walters , Abhishek Nag , Mirian Garcia-fernandez , Kejin Zhou , Gerrit Van Der Laan , Roberto Caciuffo Journal Of Physics: Condensed Matter DOI: 10.1088/1361-648X/abc4d2 Diamond Proposal Number(s): [24583] Open Access Show Abstract ▼ Abstract: Resonant inelastic x-ray spectroscopy at the uranium $N_{4}$ absorption edge at 778 eV has been used to reveal the excitations in UO$_{2}$ up to 1 eV. The earlier (1989) studies by neutron inelastic scattering of the crystal-field states within the $^{3}H_{4}$ multiplet are confirmed. In addition, the first excited state of the $^{3}F_{2}$ multiplet at $\sim$520 meV has been established, and there is a weak signal corresponding to the next excited state at $\sim$920 meV. This represents a successful application of soft x-ray spectroscopy to an actinide sample, and resolves an open question in UO$_{2}$ that has been discussed for 50 years. The technique is described and important caveats are drawn about possible future applications.	Oct 2020
I10-Beamline for Advanced Dichroism	Depth-resolved magnetization dynamics revealed by X-ray reflectometry ferromagnetic resonance D. M. Burn , S. L. Zhang , G. Q. Yu , Y. Guang , H. J. Chen , X. P. Qiu , Gerrit Van Der Laan , T. Hesjedal Physical Review Letters 125, 137201 DOI: 10.1103/PhysRevLett.125.137201 Diamond Proposal Number(s): [23895] Open Access Show Abstract ▼ Abstract: Magnetic multilayers offer diverse opportunities for the development of ultrafast functional devices through advanced interface and layer engineering. Nevertheless, a method for determining their dynamic properties as a function of depth throughout such stacks has remained elusive. By probing the ferromagnetic resonance modes with element-selective soft x-ray resonant reflectivity, we gain access to the magnetization dynamics as a function of depth. Most notably, using reflectometry ferromagnetic resonance, we find a phase lag between the coupled ferromagnetic layers in [CoFeB/MgO/Ta]4 multilayers that is invisible to other techniques. The use of reflectometry ferromagnetic resonance enables the time-resolved and depth-resolved probing of the complex magnetization dynamics of a wide range of functional magnetic heterostructures with absorption edges in the soft x-ray wavelength regime.	Sep 2020
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
I06-Nanoscience	Bacterial production of vanadium ferrite spinel (Fe,V)3O4 nanoparticles V. S. Coker , G. Van Der Laan , N. D. Telling , J. R. Lloyd , J. M. Byrne , E. Arenholz , R. A. D. Pattrick Mineralogical Magazine DOI: 10.1180/mgm.2020.55 Diamond Proposal Number(s): [838] Show Abstract ▼ Abstract: Biogenic nanoscale vanadium magnetite is produced by converting V(V)- bearing ferrihydrites through reductive transformation using the metal- reducing bacterium Geobacter sulfurreducens. With increasing vanadium in the ferrihydrite, the amount of V-doped magnetite produced decreased due to V-toxicity which interrupted the reduction pathway ferrihydrite – magnetite, resulting in siderite or goethite formation. Fe L2,3 and V L2,3 X-ray absorption spectra and data from X-ray magnetic circular dichroism analysis revealed the magnetite to contain the V in the Fe(III) Oh site, predominately as V(III) but always with a component of V(VI) present a consistent V(IV)/V(III) ratio in the range 0.28 to 0.33. The bacteriogenic production of V-doped magnetite nanoparticles from V-doped ferrihydrite is confirmed and the work reveals that microbial reduction of contaminant V(V) to V(III)/V(IV) in the environment will occur below the Fe-redox boundary where it will be immobilised in biomagnetite nanoparticles.	Jul 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

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User