Compensated ferrimagnetic oxides for rapid magnetic switchers (FEMAGSWIT)

Project Director: Dr. Maria Cristina BARTHA

Project ID: 676 PED din 21/06/2022


Project Director:  Dr. Maria Cristina Bartha (Valsangiacom)

Project Type: National

Project Program: PED

Funded by:  Romanian National Authority for Scientific Research, UEFISCDI

Contractor: National Institute of Materials Physics

Project Status: In progress

Start Date: 21 June, 2022

End Date:  21 June, 2024


Project summary: 

Electric-field control of magnetism has remained a major challenge which would greatly impact especially data storage technology, but also other types of logic and electromagnetically controlled devices. Control of magnetic properties by an electric field would enable new data storage technologies operating at low electrical power. Although the electric field could be used to manipulate a wide range of magnetic properties, e.g. Curie temperature, magnetic moment, coercivity, and magnetic anisotropy, the realization of 180° magnetization switching could only be obtained in few systems.

The scope of this project is to obtain and validate an advanced material, namely a rare earth garnet of RE3Fe5O12 type (RIG), with RE=Tb, Gd, Dy and Ho for future generations of electronic devices. The project’s general objective is to select a material (demonstration model) with suitable magnetic properties for high performance spintronic applications, namely a magnetic switching device.

The proposed material will be obtained by our original technological route that combines a cheap and facile surfactant assisted hydrothermal method to prepare mesoporous RE3Fe5O12 structures followed by Spark Plasma Sintering (SPS) and post-annealing to consolidate the obtained nanoparticle powders into high-density nano structured bulks with controlled and refined properties.

The challenge of this project is to select a material in which we could achieve a fast and robust switching of magnetization under low current excitation near room temperature. For comparison, materials obtained by the classical method (solid state reaction) will also be assessed.


Dr. Maria Cristina Bartha (Project Director)

Dr. Victor Kuncser

Dr. Petre Badica

Dr. Cezar Comanescu

Dr. Alina Crisan

Dr. Andrei Kuncser

Dr. Mihai Alexandru Grigoroscuta

Ph.D Student Andrei Alexandru-Dinu

MSc. Student  Ani Sergentu

Stage I summary:

In this first stage of the project, oxide precursor nanopulbers with garnet structure of RE3Fe5O12 type were prepared, where RE= Gd, Tb, Dy and Ho  and were complexly characterized both from a structural and morphological point of view. In order to obtain the materials, two processing methods were used (one of them being used for the first time on this type of compounds). At the same time, several studies related to the evolution of properties have been carried out, at this stage, the emphasis being placed on the magnetic properties of oxides with garnet structure obtained by the classical method.

Stage II summary:

The second stage of the experimental demonstration project  aimed at obtaining bulks with garnet structure of RE3Fe5O12, where RE = Gd, Tb, Dy and Ho  by the Spark Plasma Sintering method and their complex structural and microstructural characterization and the investigation of magnetic properties. The SPS method allows to perform sintering heat treatments at high temperatures (up to 2400 °C) using high heating and/or cooling rates (up to 500 °C/min). Among the advantages of using this method are: obtaining bulks with high density (more than 90% of the theoretical density of the processed material), maintaining low particle sizes due to the rapidity of the heat treatment, obtaining microstructural characteristics superior to those obtained by classical sintering treatments, etc. The structural and microstructural investigation of the materials reveals two phases with garnet structure: a stoichiometric phase of  (Gd3(Feoct+tet)5O12) type which is the majority (≥ 90%), in some of the samples it is even the only phase, and a phase showing cationic and/or oxygen stoichiometric defects of the  (Gd)3-x[(Fe2-x)oct(Fe3-x)tet]O12-x type. The coexistence of the two phases significantly influences the properties, especially the magnetic properties which are extremely sensitive to the local changes involving cation distribution and/or defects generated by the variation of oxygen stoichiometry. Therefore, the obtained materials show a distribution of magnetic couplings favoring the achievement of properties with varied application potential. These will be explored in the final stage of the project, the aim being to select demonstrator material with optimal properties for the proposed applications. In addition, some studies on the switching properties of the selected material have been carried out.


Web of Science articles - published or accepted:

  1. "Advance of Nanoparticles and Thin Films", Bogdana Borca and Cristina Bartha, Coatings 202212(8), 1138;
  2. "Kinetics and the Effect of Thermal Treatments on the Martensitic Transformation and Magnetic Properties in Ni49Mn32Ga19 Ferromagnetic Shape Memory Ribbons", Tolea, F.; Popescu, B.; Bartha, C.; Enculescu, M.; Tolea, M.; Sofronie, M., Magnetochemistry 20239, 7.
  3. "Up-Conversion Luminescence and Magnetic Properties of Multifunctional Er3+/Yb3+-Doped SiO2-GdF3/LiGdF4 Glass Ceramics", Secu, C.; Bartha, C.; Radu, C.; Secu, M. Magnetochemistry 20239, 11.
  4. Synthesis of CoFe2O4 Through Wet Ferritization Method Using an Aqueous Extract of Eucalyptus Leaves, Gingasu D., Culita DC., Moreno JMC., Marinescu G., Bartha C., Oprea O.,Preda S., Chifiriuc MC., Popa M., Coatings 202313(7), 1250;

International Conferences:

  1. Cristina Bartha, Andrei Alexandru Dinu, Cezar Comanescu, Simona Greculeasa, Nicusor Iacob, Aurel Leca, and Petre Badica, "Rare earth garnet of Gd3Fe5O12 type for future generation of electronic devices", 7th edition of the International Workshop Of Materials Physics, Recent Trends in Magnetism and Superconductivity, 31 of August- 2 of September, Magurele, 2022 ( poster ).
  2. Structural, Mössbauer Spectroscopy and Magnetic Investigations of Gd3Fe5O12 garnets obtained by different routes”, C. Bartha,  C. Comanescu, M. Grigoroscuta, A. Alexandru-Dinu, P. Badica and V. Kuncser, International Conference on the Applications of the Mössbauer Effect -ICAME 2023, 3- 9 Septembrie 2023, Cartagena de Indias, Columbia (Oral presentation).
  3. Magnetic Properties of Rare Earth Iron Garnets Prepared by Two Synthesis Routes”, A. Alexandru-Dinu, C. Bartha, M. Grigoroscuta, C. Comanescu, V. Kuncser and P. Badica, 8th  International Conference on Superconductivity and Magnetism,  4-11 Mai 2023, Ölüdeniz-Fethiye Turcia (Poster).
  4. Magnetic Oxide Ceramics for Spintronics Applications” C. Bartha, A. Alexandru-Dinu, M. Grigoroscuta, C. Comanescu and P. Badica, 8th  International Conference on Superconductivity and Magnetism,  4-11 Mai 2023, Ölüdeniz-Fethiye Turcia (Poster).
  5. Bulk MgB2 and Rare Earth Iron Garnets Processed by Spark Plasma Sintering”, P. Badica, 8th  International Conference on Superconductivity and Magnetism,  4-11 Mai 2023, Ölüdeniz-Fethiye Turcia (Oral presentation).


"Process for obtaining oxide materials with garnet structure based on iron and rare earths and types of systems obtained, application no A/00200 din 25/04/2023  submitted to OSIM.



Maria Cristina Bartha (Valsangiacom), PhD in Physics

Senior Researcher II

Telephone: +40-(0)21-2418 146

Department: Magnetism and Superconductivity



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