Magnetic thin films and layered heterostructures are critical components in many of the modern technologies including information storage, sensors, actuators and micro/nano-electromechanical systems, being also model systems for the investigation of magnetic phenomena. Changing the thickness and the materials parameters, the crystalline structure and morphology or by exploiting the layering and coupling with different materials (both magnetic and non-magnetic) allows a significant modulation of their properties for specific applications.
The research activity at the nM2-Lab spans from the design to the preparation and deeply magnetic characterization (experimental and simulation) of magnetic thin films and multi-layered heterostructures both for fundamental studies and applications in many technological areas. The investigation of magnetic behavior includes the study of magnetization reversal mechanism, anisotropy symmetry, interface and intergranular interactions, time-dependent phenomena and their correlation with the morpho-structural properties. During the last two decades, the research activity has been focused on high-anisotropy ferromagnetic metal alloys with perpendicular and tilted magnetic anisotropy (e.g. CoCrPtX@SiO2, L10-FePt(Cu), L10-CoPt, [Co/Pd,Pt]n) and magnetic coupled composites (hard/soft – e.g. L10-FePt/Fe(Co), FePt-based graded systems –, exchange bias systems – e.g. Co/CoO, NiO/CoPt –) for fundamental studies and magnetic recording applications. More recently studied systems include critical-element-free high-anisotropy magnetic alloys (e.g. L10-FeNi, FeCoX) and synthetic antiferromagnet-based systems (grown on both rigid and flexible substrates) for applications in the fields of information storage, technologies for sensors/actuators and biomedicine. While the focus has been on metal systems, a growing interest on thin film and multilayered heterostructures made of complex metal oxides has recently emerged. Furthermore, a particular attention is devoted to study the correlation between the magnetic behavior and the morpho-structural properties by exploiting angular/vector magnetic measurements and by investigating the structural and magnetic properties at the local scale by synchrotron X-ray techniques.
Contact Person: G. Varvaro | ISM - CNR| email: gaspare.varvaro@ism.cnr.it| Ph: +390690672651
CURRENT FOCUSES
Synthetic Antiferromagnet-based systems
Principal Investigator: G. Varvaro | email: gaspare.varvaro@ism.cnr.itStaff: S. Laureti, D. Peddis, A. Capobianchi, M. Hassan (Post-doc) Synthetic antiferromagnetic (SAFs) heterostructures consisting of two or more ferromagnetic layers separated by a metallic spacer or a tunnel barrier are of great interest for many applications (e.g. spintronics devices, biomedicine) due to their peculiar properties and high tunability via layer thickness and material composition.
At the nM2-Lab, the research efforts are being invested on the design of systems and devices exploiting SAF thin films with perpendicular magnetic anisotropy (PMA) based on Co/Pd(Pt,Ni) multilayers. A particular attention is devoted to magneto-resistive devices on rigid and flexible substrates and synthetic antiferromagnetic microdisks for biomedical applications.
The research activity is carried-out in strict collaboration with Prof. M. Albrecht of the University of Augsburg (Germany).
High-Anisotropy Ferromagnets
Principal Investigator: G. Varvaro | email: gaspare.varvaro@ism.cnr.itStaff: S. Laureti, E. Agostinelli, A.M. TestaHigh-anisotropy ferromagnetic thin films are critical components in many technological applications, such as magnetic data storage, spintronic devices, sensors and micro/nano-electromechanical systems, among others.
In strict collaboration with many national and international groups, the research activity at nM2-Lab has been devoted to the design and thoroughly magnetic characterization of hard magnetic materials with perpendicular magnetic anisotropy for both conventional and next generation magnetic recording media for Hard Disk Drives as well as on the study of novel high-anisotropy materials free of critical elements.
Angular and Vector Magnetic Measurements
Principal Investigator: G. Varvaro | email: gaspare.varvaro@ism.cnr.itStaff: S. Laureti, A.M. TestaDeveloping novel magnetic materials and devices requires a thoroughly understanding of the underlying magnetic phenomena and their correlation with the structural and microstructural properties. Owing to the anisotropic nature of crystalline thin films and heterostructures, studying angular and vector magnetic properties is of crucial importance to disclose the physical properties of a system.
At the nM2-Lab, in addition to the most common field- and temperature-dependent magnetization measurements, advanced angular and vector magnetic measurements are exploited to investigate the magnetization reversal mechanism as well as the symmetry and magnitude of the magnetic anisotropy in thin films and heterostructures.
Synchrotron X-ray Techniques
Principal Investigator: S. Laureti | email: sara.laureti@ism.cnr.itStaff: G. Varvaro, A. CapobianchiX-ray synchrotron facilities play a key role in addressing fundamental research issues related to nanostructured magnetic systems. Taking advantage of its peculiar characteristics (high brilliance, tunable wavelength, collimation, and polarization) the synchrotron light can be absorbed by a material or interact with the atoms, giving rise to diffraction or scattering phenomena, which can be exploited to get information about the composition of a sample, including the type and location of individual atoms within it.
The high selectivity and sensitivity of synchrotron-based X-ray Absorption Spectroscopy (XAS) techniques are exploited at the nM2-Lab to investigate the atomic arrangement in magnetic thin films and nanoparticles with a special emphasis to L10 magnetic alloys, whose magnetic properties strongly depend on the chemical order.
