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

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

Instruments / Technical Area	Publication Details	Published
I06-Nanoscience	Voltage-driven annihilation and creation of magnetic vortices in Ni discs Massimo Ghidini , Rhodri Mansell , Raffaele Pellicelli , David Pesquera , Bhaskaran Nair , Xavier Moya , Saeedeh Farokhipoor , Francesco Maccherozzi , Crispin Barnes , Russell Cowburn , Sarnjeet Dhesi , Neil Mathur Nanoscale DOI: 10.1039/C9NR08672B Diamond Proposal Number(s): [11843] Show Abstract ▼ Abstract: Using photoemission electron microscopy (PEEM) to image ferromagnetism in polycrystalline Ni disks, and ferroelectricity in their single-crystal BaTiO3 substrates, we find that voltage-driven 90 ferroelectric domain switching serves to reversibly annihilate each magnetic vortex via uniaxial compressive strain, and that the orientation of the resulting bi domain reveals the chirality of the annihilated vortex. (Micromagnetic simulations reveal that only 60% of this strain was required for annihilation.) Voltage control of magnetic vortices is novel, and should be energetically favourable with respect to the use of a magnetic field or an electrical current. In future, stray field from bi domains could be exploited to read vortex chirality. Given that core polarity can already be read via stray field, our work represents a step towards four-state low power memory applications.	Feb 2020
I06-Nanoscience	Exchange-bias via nanosegregation in novel Fe 2–x Mn 1+x Al ( x = –0.25, 0, 0.25) Heusler films Samer Kurdi , Massimo Ghidini , Giorgio Divitini , Bhaskaran Nair , Ahmed Kursumovic , Paola Tiberto , Sarnjeet Dhesi , Zoe Barber Nanoscale Advances DOI: 10.1039/C9NA00689C Diamond Proposal Number(s): [17563] Open Access Show Abstract ▼ Abstract: Exchange-bias has been reported in bulk nanocrystalline Fe2MnAl, but individual thin films of this Heusler alloy have never been studied so far. Here we study the structural and magnetic properties of nanocrystalline thin films of Fe2–xMn1+xAl (x = –0.25, 0, 0.25) obtained by sputtering and ex-situ post-deposition annealing. We find that Fe2MnAl films display exchange-bias, and that varying Mn concentration determines the magnitude of the effect, which can be either enhanced (in Fe1.75Mn1.25Al) or suppressed (in Fe2.25Mn0.75Al). X-ray diffraction (XRD) shows that our films present a mixed L21-B2 Heusler structure where increasing Mn concentration favors the partial transformation of the L21 phase into the B2 phase. Scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX) reveal that this composition-driven L21→B2 transformation is accompanied by phase segregation at the nanoscale. As a result, the Fe2–xMn1+xAl films that show exchange-bias (x = 0, 0.25) are heterogeneous, with nanograins of an Fe-rich phase embedded in a Mn-rich matrix (a non-negative matrix factorisation algorithm was used to give an indication of the phase composition from EDX data). Our comparative analysis of XRD, magnetometry and X-ray magnetic circular dichroism (XMCD), shows that Fe-rich nanograins and Mn-rich matrix are composed of a ferromagnetic L21 phase and an antiferromagnetic B2 phase, respectively, thus revealing that exchange-coupling between these two phases is the cause of the exchange-bias effect. Our work should inspire the development of single-layer, environmentally-friendly spin valve devices based on nanocomposite Heusler films.	May 2020
I06-Nanoscience	Voltage-driven displacement of magnetic vortex cores M. Ghidini , R. Pellicelli , R. Mansell , D. Pesquera , B. Nair , X. Moya , S. Farokhipoor , F. Maccherozzi , C. H. W. Barnes , R. P. Cowburn , S. S. Dhesi , N. D. Mathur Journal Of Physics D: Applied Physics 53 DOI: 10.1088/1361-6463/aba01d Diamond Proposal Number(s): [11843] Open Access Show Abstract ▼ Abstract: Magnetic vortex cores in polycrystalline Ni discs underwent non-volatile displacements due to voltage-driven ferroelectric domain switching in single-crystal BaTiO3. This behaviour was observed using photoemission electron microscopy to image both the ferromagnetism and ferroelectricity, while varying in-plane sample orientation. The resulting vector maps of disc magnetization match well with micromagnetic simulations, which show that the vortex core is translated by the transit of a ferroelectric domain wall, and thus the inhomogeneous strain with which it is associated. The non-volatility is attributed to pinning inside the discs. Voltage-driven displacement of magnetic vortex cores is novel, and opens the way for studying voltage-driven vortex dynamics.	Oct 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