Weakly coupled synthetic antiferromagnetic nanodisks with perpendicular magnetic anisotropy for lab-on-chip devices

Synthetic antiferromagnetic particles with perpendicular magnetic anisotropy offer a highly desirable platform for use in fluidic applications. This work illustrates their high level of switching field tunability and demonstrates the ability to use particle design to overcome unfavorable hysteretic changes during patterning to manufacture functional, low switching field nanodisks. This makes them ideal candidates for lab-on-chip technologies such as microfluidic sorting or detection devices.Rosetrees Trus

High-yield fabrication of perpendicularly magnetised synthetic antiferromagnetic nanodiscs

AbstractSynthetic antiferromagnetic (SAF) particles with perpendicular anisotropy display a number of desirable characteristics for applications in biological and other fluid environments. We present an efficient and effective method for the patterning of ultrathin Ruderman-Kittel-Kasuya-Yoshida coupled, perpendicularly magnetised SAFs using a combination of nanosphere lithography and ion milling. A Ge sacrificial layer is utilised, which provides a clean and simple lift-off process, as well as maintaining the key magnetic properties that are beneficial to target applications. We demonstrate that the method is capable of producing a particularly high yield of well-defined, thin film based nanoparticles.European Research Council (No.779822

The effect of underlayers on the reversal of perpendicularly magnetized multilayer thin films for magnetic micro- and nanoparticles

Perpendicularly magnetized microparticles offer the ability to locally apply high torques on soft matter under an applied magnetic field. These particles are engineered to have a zero remanence magnetic configuration via synthetic antiferromagnetic coupling using a Ru coupling interlayer. The flexibility offered by the top down thin film fabrication process in a CoFeB/Pt perpendicular thin film is demonstrated by using the Pt interlayer thicknesses in a Pt/Ru/Pt antiferromagnetic coupling multilayer to tune the applied magnetic field value of the easy axis spin-flip transition to saturation and hence the field value at which the magnetic particles are magnetically activated via a distinct transition to saturation. The importance of a Ta buffer layer on the magnetic behavior of the stack is shown. While Au capping layers are desirable for biotechnology applications, we demonstrate that they can drastically change the nucleation and propagation of domains in the film, thereby altering the reversal behavior of the thin film. The effect of Au underlayers on a multilayer thin film composed of repeated motifs of a synthetic antiferromagnetic building block is also investigated.</jats:p

Magnetic particles with perpendicular anisotropy for mechanical cancer cell destruction

We demonstrate the effectiveness of out-of-plane magnetized magnetic microdiscs for cancer treatment through mechanical cell disruption under an applied rotating magnetic field. The magnetic particles are synthetic antiferromagnets formed from a repeated motif of ultrathin CoFeB/Pt layers. In-vitro studies on glioma cells are used to compare the efficiency of the CoFeB/Pt microdiscs with Py vortex microdiscs. It is found that the CoFeB/Pt microdiscs are able to damage 62 ± 3% of cancer cells compared with 12 ± 2% after applying a 10 kOe rotating field for one minute. The torques applied by each type of particle are measured and are shown to match values predicted by a simple Stoner-Wohlfarth anisotropy model, giving maximum values of 20 fNm for the CoFeB/Pt and 75 fNm for the Py vortex particles. The symmetry of the anisotropy is argued to be more important than the magnitude of the torque in causing effective cell destruction in these experiments. This work shows how future magnetic particles can be successfully designed for applications requiring control of applied torques.This research was funded by NIH grant R01NS077388 ‘Magnetic Vortex Mixrodiscs for Glioma therapy’, the European Community under the Seventh Framework Program ERC contract No. 247368: 3SPIN, and the EPSRC Cambridge NanoDTC, EP/G037221/1

Research data supporting "The mechanical response in a fluid of synthetic antiferromagnetic and ferrimagnetic microdiscs with perpendicular magnetic anisotropy"

This dataset is the magnetometry data for the publication listed above with Applied Physics Letters

Research data supporting "Towards Flexible Spintronics: Perpendicularly Magnetized Synthetic Antiferromagnetic Thin films and Nanowires On Polyimide Substrates"

Magnetometry and relevant atomic force microscopy data corresponding to the figures in the publication.This work was supported by the European Community under the Seventh Framework Program ERC [grant number 247368: 3SPIN], the EPSRC Early Career Fellowship [grant number EP/M008517/1], a Winton Fellowship, EMRP JRP EXL04 SpinCal where the EMRP is jointly funded by the EMRP participating countries within EURAMET and the EU, the EPSRC Cambridge NanoDTC [grant number EP/G037221/1] and the Wellcome Trust

Research data supporting "The effect of underlayers on the reversal of perpendicurlarly magnetized multilayer thin films for magnetic micro- and nanoparticles"

This dataset is magnetometry data related to the publication

Research data supporting "Highly tunable perpendicularly magnetized synthetic antiferromagnets for biotechnology applications"

This is a series of magnetic data on synthetic antiferromagetic (SAF) thin films and 2 micron SAF particles. The data presented here is either Polar MOKE, VSM or simulations and is described further in the Metadata file attached with text. All measurements were done in, and on materials fabricated in, the Thin Film Magnetism Group at the University of Cambridge under Professor R. P. Cowburn.This work was supported by the ERC [Seventh Framework Program ERC Contract No. 247368: 3SPIN], EPSRC [EPSRC Cambridge NanoDTC, EP/G037221/1], and NIH [grant number R01NS077388 `Magnetic Vortex Microdiscs for Glioma Therapy']