WP 2

The Consortium will focus on the application of SPM techniques, namely magnetic force and piezoresponse force microscopy (MFM and PFM), to study the mechanisms of the ME coupling at the nanoscale both in composites and single-phase multiferroics. The ME coupling will be directly probed by the observation of the effect of an external magnetic/electric field on the local piezoelectric/magnetic response and corresponding domain patterns. This will allow us obtaining critical information on the local ME efficiency and finally to improve the device performance. Besides SPM the ESR will get training in preparation and characterization of multiferroics. The training courses offered jointly by NPL and UAVR will initially concentrate on the understanding of MF materials and the standard techniques for their characterisation. Combined with this, NPL provides an industrial focus to the work taking place and imparts an appreciation of the importance of accurate, quantifiable measurements. This work plan lays out a fundamental basis to the research area before developing into novel materials and measurement techniques. The ESR will be integrated into a research programme of significant scientific and industrial importance.

Work Package 2a: Nanoscale properties of multiferroic composites

ESR5 – Rui Lopes. Host Institute: National Physical Laboratory, Teddington, United Kingdom.

The project focuses on multiferroic ferroelectric/magnetic Nanocomposites at University of Leeds (e.g., PZT-NiFe2O4. PZT-metglass, and BaTiO3-hexagonal ferrites) which will be studied by both macroscopic (University of Aveiro, UAVR) and nanoscale techniques (NPL, secondment to NT-MDT). The research will uncover the links between macroscopic and local magnetoelectric properties leading to potential new coupling effects and useful nanodevices. Both particulate composites as well as laminar structures with 2-2 type connectivity will be produced and studied. The project will proceed initially at UAVR where the mutliferroic samples will be synthesized. The work will progress at NPL where combined techniques (such as PFM in a magnetic field) are being devised to directly measure coupled interactions at the nanoscale. The SPM facilities at NPL have been developed with proprietary capabilities aimed at multiferroic measurements (especially magnetoelectric coupling) combined with in-situ magnetic field capabilities.

Work Package 2b: Magnetoelectric effect in single phase multiferroics

ESR6- Leonard Frederic Henrichs.Host University: University of Leeds, Leeds, United Kingdom. Secondments: University of Aveiro, Aveiro, Portugal, University of Duisburg/Essen, Essen, Germany.

One of the greatest opportunities for enhanced multiferroic coupling lies in the existence of a multistate phase boundary in BiFeO3-PbTiO3 system at which the crystallographic phase, polar order parameter, and magnetic order parameter all undergo step changes as a function of composition. PFM and MFM as a function of applied magnetic and electric fields will be used to characterize the changes of phase at the nanoscale. In addition, the training in SPM will be complemented by training in relevant advanced in situ diffraction techniques under applied electric and magnetic fields using the synchrotron facilities of Diamond and neutron diffraction at ISIS (UK) and ILL (France). Exchange visits will take place to develop an improved model of magnetoelastic and magnetoelectric interactions at the nanoscale (UDE) and to validate scanning probe observations at UL on an alternative platform (UAVR). Note that ECP partners have strong competences in this field and rather easy access to LLB facilities (very close geographically and strong interactions through associated researchers).Beside the BiFeO3-PbTiO3 I also work on the PbZr0.53Ti0.47O3-PbFe0.67W0.33O3 (PZT-PFW) system which is a relatively new and promising room-temperature multiferroic. In both systems, mechanisms of phase transitions and magnetoelectric coupling at the nanoscale, will be investigated with scanning probe techniques in-situ under externally applied fields. Here, the focus lies on Piezoresponse-Force-Microscopy (PFM) under applied magnetic fields.

WP2b_PFMimage WP2b_PEMH

Work Package 2c: Magnetoelectric effect in core-shell multiferroic nanocomposites

ESR7- Harsh Trivedi.Host University: University of Duisburg-Essen, Essen, Germany. Secondments: National Physical Laboratory, Teddington, London, England ; Ecole Centrale Paris, Châtenay-Malabry, France.

This project involves local probing of Magnetoelectric-Effect using (but not limited to) Scanning Probe Microscopy tools like Piezoresponse Force Microscopy (PFM) and magnetic Force Microscopy (MFM), on composite multiferroics like BaTiO3 – CoFe2O4 system, with a core-shell type of phase connectivity.
The fact that bulk magnetoelectric measurements suffers sever drawback owing to the heterogeneous nature of the materials, have led to the motivation for utilizing Scanning Probe Microscopy techniques to explore the ME effect locally. Firstly the goal is to develop different ways in which this can be done. Secondly the developed experiments will be used to measure the ME effect locally try to correlate it with the bulk effect. There is also a possibility of resolving the relation between different type of phase connectivity (e.g. 0 – 3, 1 – 3 etc.).
Variable field (Magnetic/Electric) SPM will be the principle tool to explore the ME effect locally. In addition to this Confocal Raman imaging is being used to visualize the spatial nuances created due to strain mediation. At a later stage the results will be compared with theoretical findings obtained using Finite Element Method, which are being carried out parallel in WP1d.