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

8 items found (0 items not approved), displaying all items.1

Instruments / Technical Area	Publication Details	Published
I06-Nanoscience	Magnetisation configuration in arrays of permalloy rectangles and its impact on magnetisation reversal P. J. Newton , N. B. Devlin , S. M. Masur , M. Ghidini , D. Backes , F. Maccherozzi , A A Pacheco-Pumaleque , M A González Esqueche , C. H. W. Barnes Materials Research Express 8 DOI: 10.1088/2053-1591/ac2442 Diamond Proposal Number(s): [24373] Open Access Show Abstract ▼ Abstract: The remanent domain structures of composite element magnetic barcodes have been imaged using photo-emission electron microscopy with contrast from x-ray magnetic circular dichroism (XMCD-PEEM) and analysed with reference to the results of micromagnetic simulations. The magnetisation configuration at the end of wide strips is found to be perpendicular to the majority magnetisation direction. This transitions to an incomplete rotation for nominal strip widths below 300 nm and is found to affect the mechanics of magnetisation reversal for nominal strip widths below 200 nm, owing to a difference in magnetisation orientation when an external magnetic field is applied that is just smaller than the magnetic coercivity of the structures and a corresponding change in reversal dynamics. This change in domain structure as strip width decreases is consistent with both the influence of shape anisotropy and with measurements of magnetic hysteresis. The magnetisation reversal characteristics of composite element structures are found to be dependent on the relative magnetisation configurations of neighbouring strips, which in turn are found to vary stochastically upon the application and removal of a magnetic field along the easy axis of the structure. It is found that the application of a canted field is necessary to ensure sharp, consistent magnetisation reversal of bits when writing a binary code. These results confirm that either improved lithography of narrower strips or non-rectangular elements would be necessary to further increase the number of individually programmable bits in a barcode.	Sep 2021
I06-Nanoscience	Identification of Néel vector orientation in antiferromagnetic domains switched by currents in NiO/Pt thin films C. Schmitt , L. Baldrati , L. Sanchez-Tejerina , F. Schreiber , A. Ross , M. Filianina , S. Ding , F. Fuhrmann , R. Ramos , F. Maccherozzi , D. Backes , M.-A. Mawass , F. Kronast , S. Valencia , E. Saitoh , G. Finocchio , M. Klaui Physical Review Applied 15 DOI: 10.1103/PhysRevApplied.15.034047 Diamond Proposal Number(s): [22448] Show Abstract ▼ Abstract: Understanding the electrical manipulation of the antiferromagnetic order is a crucial aspect to enable the design of antiferromagnetic devices working at THz frequencies. Focusing on collinear insulating antiferromagnetic Ni O / Pt thin films as a materials platform, we identify the crystallographic orientation of the domains that can be switched by currents and quantify the Néel-vector direction changes. We demonstrate electrical switching between different T domains by current pulses, finding that the Néel-vector orientation in these domains is along [ ± 5 ± 5 19], different compared to the bulk ⟨ 112 ⟩ directions. The final state of the in-plane component of the Néel vector n IP after switching by current pulses j along the [ 1 ± 1 0 ] directions is n IP ∥ j . By comparing the observed Néel-vector orientation and the strain in the thin films, assuming that this variation arises solely from magnetoelastic effects, we quantify the order of magnitude of the magnetoelastic coupling coefficient as b 0 + 2 b 1 = 3 × 10 7 J / m 3 . This information is key for the understanding of current-induced switching in antiferromagnets and for the design and use of such devices as active elements in spintronic devices.	Mar 2021
I06-Nanoscience	Electrical detection of the spin reorientation transition in antiferromagnetic TmFeO3 thin films by spin Hall magnetoresistance S. Becker , A. Ross , R. Lebrun , L. Baldrati , S. Ding , F. Schreiber , F. Maccherozzi , D. Backes , M. Klaui , G. Jakob Physical Review B 103 DOI: 10.1103/PhysRevB.103.024423 Diamond Proposal Number(s): [23819] Show Abstract ▼ Abstract: Tm Fe O 3 (TFO) is a canted antiferromagnet that undergoes a spin reorientation transition (SRT) with temperature between 82 and 94 K in single crystals. In this temperature region, the Néel vector continuously rotates from the crystallographic c axis (below 82 K) to the a axis (above 94 K). The SRT allows for a temperature control of distinct antiferromagnetic states without the need for a magnetic field, making it apt for applications working at terahertz frequencies. For device applications, thin films of TFO are required as well as an electrical technique for read-out of the magnetic state. Here, we demonstrate that orthorhombic TFO thin films can be grown by pulsed laser deposition and the detection of the SRT in TFO thin films can be accessed by making use of the all-electrical spin Hall magnetoresistance, in good agreement for the temperature range where the SRT occurs in bulk crystals. Our results demonstrate that one can electrically detect the SRT in insulators.	Jan 2021
I06-Nanoscience	An insulating doped antiferromagnet with low magnetic symmetry as a room temperature spin conduit Andrew Ross , Romain Lebrun , Lorenzo Baldrati , Akashdeep Kamra , Olena Gomonay , Shilei Ding , Felix Schreiber , Dirk Backes , Francesco Maccherozzi , Daniel A. Grave , Avner Rothschild , Jairo Sinova , Mathias Klaui Applied Physics Letters 117 DOI: 10.1063/5.0032940 Diamond Proposal Number(s): [23819] Show Abstract ▼ Abstract: We report room-temperature long-distance spin transport of magnons in antiferromagnetic thin-film hematite doped with Zn. The additional dopants significantly alter the magnetic anisotropies, resulting in a complex equilibrium spin structure that is capable of efficiently transporting spin angular momentum at room temperature without the need for a well-defined, pure easy-axis or easy-plane anisotropy. We find intrinsic magnon spin-diffusion lengths of up to 1.5 μm, and magnetic domain governed decay lengths of 175 nm for the low-frequency magnons, through electrical transport measurements demonstrating that the introduction of nonmagnetic dopants does not strongly reduce the transport length scale, showing that the magnetic damping of hematite is not significantly increased. We observe a complex field dependence of the nonlocal signal independent of the magnetic state visible, in the local magnetoresistance and direct magnetic imaging of the antiferromagnetic domain structure. We explain our results in terms of a varying and applied field-dependent ellipticity of the magnon modes reaching the detector electrode allowing us to tune the spin transport.	Dec 2020
I06-Nanoscience	Magnetic and structural properties of CoFeB thin films grown by pulsed laser deposition Geet Awana , Chris Cox , Guru Venkat , Kelly Morrison , Zhaoxia Zhou , Dirk Backes Materials Research Express 7 DOI: 10.1088/2053-1591/abc124 Diamond Proposal Number(s): [23748] Open Access Show Abstract ▼ Abstract: The emergence of thin film CoFeB has driven research and industrial applications in the past decades, with the magnetic random access memory (MRAM) the most prominent example. Because of its beneficial properties, it fulfills multiple functionalities as information-storing, spin-filtering, and reference layer in magnetic tunnel junctions. In future, this versatility can be exploited beyond the traditional applications of spintronics by combining with advanced materials, such as oxide-based materials. Pulsed laser deposition (PLD) is their predominant growth-method, and thus the compatibility of CoFeB with this growth technique will be tested here. This encompasses a comprehensive investigation of the structural and magnetic propoperties. In particular, we find a substantial 'dead' magnetic layer and confirm that it is caused by oxidation employing the x-ray magnetic circular dichroism (XMCD) effect. The low damping encountered in vector network analyzer-based ferromagnetic resonance (VNA-FMR) renders them suitable for magnonics applications. These findings demonstrate that CoFeB thin films are compatible with emergent, PLD-grown materials, ensuring their relevance for future applications.	Oct 2020
I06-Nanoscience	Magnetic-field-induced domain-wall motion in permalloy nanowires with modified Gilbert damping Thomas Moore , Phillipe Mohrke , Lutz Heyne , Andreas Kaldun , Mathias Kläui , Dirk Backes , Jan Rhensius , Laura Heyderman , Jan-ulrich Thiele , Georg Woltersdorf , Arantxa Rodriguez , Frithjof Nolting , Tevfik Mentes , Miguel Nino , Andrea Locatelli , Alessandro Potenza , Helder Marchetto , Stuart Cavill , Sarnjeet Dhesi Physical Review B 82 (9) DOI: 10.1103/PhysRevB.82.094445 Show Abstract ▼ Abstract: Domain wall (DW) depinning and motion in the viscous regime induced by magnetic fields, are investigated in planar permalloy nanowires in which the Gilbert damping is tuned in the range 0.008–0.26 by doping with Ho. Real time, spatially resolved magneto-optic Kerr effect measurements yield depinning field distributions and DW mobilities. Depinning occurs at discrete values of the field which are correlated with different metastable DW states and changed by the doping. For α<0.033, the DW mobilities are smaller than expected while for α>=0.033, there is agreement between the measured DW mobilities and those predicted by the standard one-dimensional model of field-induced DW motion. Micromagnetic simulations indicate that this is because as increases, the DW spin structure becomes increasingly rigid. Only when the damping is large can he DW be approximated as a pointlike quasiparticle that exhibits the simple translational motion predicted in the viscous regime. When the damping is small, the DW spin structure undergoes periodic distortions that lead to a velocity reduction. We therefore show that Ho doping of permalloy nanowires enables engineering of the DW depinning and mobility, as well as the extent of the viscous regime.	Sep 2010
I06-Nanoscience	Scaling of spin relaxation and angular momentum dissipation in permalloy nanowires T. Moore , M. Klaui , L. Heyne , P. Mohrke , D. Backes , J. Rhensius , U. Rudiger , L. Heyderman , J.-u. Thiele , G. Wolterstorf , C. Back , A. Fraile Rodriquez , F. Nolting , T. Mentes , M. Nino , A. Locatelli , S. Dhesi , S. Cavill , H. Marchetto , A. Potenza Physical Review B 80 (13), 132403 DOI: 10.1103/PhysRevB.80.132403 Show Abstract ▼ Abstract: We study the relationship between the damping (alpha) and the nonadiabaticity of the spin transport (beta) in permalloy nanowires. alpha is engineered by Ho doping, and from the characteristics of the current-induced domain-wall velocity, determined by high-resolution x-ray magnetic circular-dichroism photoemission electron microscopy, beta due to spin relaxation is measured. We find that beta scales with alpha and conclude that the spin relaxation that leads to nonadiabatic spin torque originates from the same underlying mechanism as the angular momentum dissipation that causes viscous damping.	Oct 2009
I06-Nanoscience	Domain wall velocity measurement in permalloy nanowires with X-ray magnetic circular dichroism imaging and single shot Kerr microscopy T. A. Moore , M. Klaui , L. Heyne , P. Möhrke , D. Backes , J. Rhensius , U. Rüdiger , L. J. Heyderman , T. O. Mentes , M. A. Niño , A. Locatelli , A. Potenza , S. S. Dhesi , S. Cavill , H. Marchetto Journal Of Magnetism And Magnetic Materials DOI: 10.1016/j.jmmm.2009.06.048 Show Abstract ▼ Abstract: Domain walls (DWs) propagated along nanoscale magnetic wires by current or field pulses could potentially be used for data storage or logic applications, but the understanding of the DW dynamics, particularly under the influence of spin-polarized current, is incomplete. Measuring the velocity can give insights into the physics of the DW motion. Here we demonstrate DW velocity measurements in permalloy (Ni80Fe20Ni80Fe20) nanowires (1500 nm width and 20 nm thickness) using the techniques of X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) to image the magnetic contrast in the nanowires, and single shot Kerr microscopy, which allows for dynamic measurements. The magnetic imaging yields the average velocity as well as information on the DW spin structure, whereas the single shot method highlights the stochastic nature of the DW motion.	Jun 2009

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