BrainMap

Dr. Radu-Cristian Gavrea

- INSTITUTUL NATIONAL DE CERCETARE DEZVOLTARE PENTRU TEHNOLOGII IZOTOPICE SI MOLECULARE I N C D T I M

Researcher

Expertise & keywords

New Heusler materials for spintronics applications Call name: Projects for Young Research Teams - RUTE -2014 call
PN-II-RU-TE-2014-4-0009 2015 - 2017

Role in this project:

Coordinating institution: UNIVERSITATEA BABES BOLYAI

Project partners: UNIVERSITATEA BABES BOLYAI (RO)

Affiliation: UNIVERSITATEA BABES BOLYAI (RO)

Project website: http://municheos.wix.com/dianabenea#!pn-ii-ru-te-2014-4-0009/c1pz

Abstract:

The spectacular development of application in the field of magnetic sensors and memories enhanced the interest for new materials able to optimize the performances of the related devices. In this context, the present project proposes the investigation of the electronic structures and magnetic properties of a several half-metal ferrimagnets of Heusler type. The half metal ferrimagnets with high spin polarization, presenting a Curie temperature above the room temperature would represent an ideal option for magnetoelectronic devices due to the very low energy losses. A special role in the fundamental research included in this project is attributed to the electronic band structure calculations in order to predict the magnetic and electronic properties of half-metal compounds. Complementarily, experimental research is proposed to investigate the compounds, some of them being proposed to be prepared for the first time. The combined approach used by our research team will contribute to understanding the mechanism of half-metallicity and ferrimagnetism within these compounds, driven by the chemical composition and by exchange interactions responsible the magnetic ordering. On the basis of our research, we expect (1) to be able to give predictions of new classes of HMFi materials and (2) to discover new materials with real potential for spintronic applications.

Physics and Fabrication of Magnetic Thin Films Call name: Projects for Young Research Teams - RUTE -2014 call
PN-II-RU-TE-2014-4-2360 2015 - 2017

Role in this project:

Coordinating institution: UNIVERSITATEA BABES BOLYAI

Project partners: UNIVERSITATEA BABES BOLYAI (RO)

Affiliation: UNIVERSITATEA BABES BOLYAI (RO)

Project website: http://www.phys.ubbcluj.ro/~sever.mican/TE2015

Abstract:

New breakthroughs in materials often have great impact on technological progress and can influence economies and even societies. In recent years there has been a dramatic increase in the interest towards applications. In this project we propose the investigation of thin films with potential future applications in the field of memory devices and reduced-scale engineering. Multilayer magnetic films where exchange coupling between dissimilar phases can be used to tailor the magnetic response. Perpendicular exchange coupled composite or exchange spring media have recently been introduced as candidate systems in which the magnetic response can be controlled. Perpendicular exchange spring systems, systems on which we will focus, consist of exchange-coupled hard and soft magnetic layers with respectively out-of-plane and in-plane easy magnetization axes. Our approach is a complex one covering the theoretical and the experimental study of the investigated thin film spring magnets.

High energy efficient permanent magnets without rare-earth elements Call name: Joint Applied Research Projects - PCCA 2013 - call
PN-II-PT-PCCA-2013-4-0971 2014 - 2017

Role in this project:

Coordinating institution: INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA

Project partners: INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA (RO); UNIVERSITATEA BABES BOLYAI (RO); PurTech SRL (RO)

Affiliation: UNIVERSITATEA BABES BOLYAI (RO)

Project website: http://www.infim.ro/projects/high-energy-efficient-permanent-magnets-without-rare-earth-elements

Abstract:

This project aims at producing, characterizing and optimizing the magnetic properties of a new class of permanent magnets with high energy efficiency based on iron nitride Fe16N2 with martensite structure. Theoretical predictions for this permanent magnet indicate a maximum energy product (BH)max of up to twice the theoretically maximum allowed for the highest performance magnet up to date, namely Nd2Fe14B. The project addresses a theme that became an imperative of global research and development activities taking into account the tremendous increase of the price of rare earths. It follows a multi-disciplinary approach to the problem. Theoretical calculations based on density functional theory are used for choosing optimal doping elements (transition metals and non-metals) of Fe16N2 which show a favourable effect on increasing thermodynamic stability and also in magnetic properties improvement, i.e. increase of magnetization (via population of sublattices presenting ferrimagnetic configuration) and anisotropy. Simulations of the Fe16N2 magnetic particles embedded in matrices will allow us directing preparation methods in order to obtain magnetic particle size and morphology suitable for enhanced coercivity and high remanence magnetization. Several preparation routes will converge on the obtaining of the compound Fe16N2 and other similar. A first route of preparation uses wet chemical methods that allow obtaining Fe16N2 doped particles. Firstly, it will be obtained the iron oxide or iron oxy-hydroxide precursor with controlled morphology and size using different chemical methods in solution. Subsequently, by thermal treatments of the iron oxide or oxy-hydroxide precursors in hydrogen and ammonia atmosphere one gets Fe16N2 fine magnetic particles with needle-like or ellipsoidal shape that show an important shape anisotropy and high coercivity. The second procedure is to obtain nanocomposites based on Fe16N2 by ball milling the iron powders and doping elements under hydrogen and nitrogen/ammonia reactive atmosphere. Processing of the milled composites and Fe16N2 magnetic particles doped with transition metals and non-metals will be performed using a glove box with controlled atmosphere in order to avoid the exposure to oxygen and moisture from air. Procedures for mixing with binder, orientation in applied magnetic field, pressing and sintering for long time at temperatures below 200 0C will allow to obtain anisotropic permanent magnets based on Fe16N2 with high coercivity and remanence magnetization. The energy product of this magnet will be higher than that of cheap magnets that do not contain rare earth. The magnetic particles and final sintered magnets will by characterized by X-Ray diffraction, neutron diffraction, electron microscopy. Iron-containing phases will be analyzed by Mossbauer spectroscopy. A complex characterization of the magnetic properties (hysteresis, saturation and remanence magnetization, coercivity) will be performed. Optimization of the magnetic properties will assume a permanent feedback between preparation methods – structural / compositional characterization – magnetic properties. The magnets will be coated against corrosion. The new innovative technologies used to produce these magnets will be the subject of patent application. The main outcome of the project, after performing the project activities, will be the permanent magnet without rare earth, which has higher energy product than cheap commercial magnets. A part of the results, which are not subject to patenting, will be disseminated through ISI publications and communications at international conferences.

Interphase Exchange Coupling in Hard/Soft Magnetic Nanocomposite Call name: Exploratory Research Projects - PCE-2012 call
PN-II-ID-PCE-2012-4-0470 2013 - 2016

Role in this project:

Coordinating institution: UNIVERSITATEA BABES BOLYAI

Project partners: UNIVERSITATEA BABES BOLYAI (RO)

Affiliation: UNIVERSITATEA BABES BOLYAI (RO)

Project website: http://www.phys.ubbcluj.ro/~viorel.pop/PN-II-ID-PCE-2012-4-0470/pn2.html

Abstract:

Exchange-spring magnets are formed of soft and hard magnetic phases dispersed on the nanometric scale and coupled by exchange interaction. The interphase exchange coupling is strongly influenced by the microstructure. Magnetic nanocomposites coupled by exchange interactions will be obtained by different methods: mechanical milling/alloying (powders), rapid quenching and sputtering (thin films), methods which combined with thermal treatments will optimize the structure and microstructure. The elaboration techniques will cause modifications to microstructures with variable dimensionality 2D, 2D-3D or 3D. These microstructures will allow experimental and theoretical study of the correlation between microstructure and exchange coupling of the soft and the hard magnetic phases. Aside the optimal microstructure, the performances of nanocomposite materials coupled by exchange interactions can be influenced by the type of soft and, mainly, hard magnetic phases. Groups of hard/soft magnetic phases, adequate for obtaining of a nanocomposite with good coercivity and high remanence will be elaborated and studied. We envisaging to exploit new lean or non-rare-earth hard magnetic phases with a high anisotropy. On the other hand, the soft phase should have a magnetization as high as possible (Fe, Fe-Co or other phases based on Fe). We are aiming for a fundamental high-level study on the inter-phase exchange coupling and to propose a possible plan for future applications.

FILE DESCRIPTION	DOCUMENT
List of research grants as project coordinator or partner team leader
Significant R&D projects for enterprises, as project manager
R&D activities in enterprises
Peer-review activity for international programs/projects