Research Groups

RESEARCH UNIT: Advanced Structural and Functional Characterization

Crystallography of Magnetic and Electronic Oxides and Surfaces (CMEOS)

Chiral and noncollinear magnetic orders provide excellent opportunities for the electric control of magnetism thanks to the coupling between electron spin and its orbital motion. Symmetry motivated approaches anticipate the identification on new improper magnetoelectric multiferroics and allow to tackle coupled transitions in frustrated oxides.

The activities of the Crystallography of Magnetic and Electronic Oxides and Surfaces (CMEOS) group are based on the application of chemical and magnetic crystallography methods to the investigation of emergent functional oxides. Combining an intensive use of Large Scale Facilities (such as neutron and synchrotron sources) with symmetry analysis methodologies, we investigate the symmetry-properties relationship associated to structural, magnetic or electronic orders in functional oxides.

Current research lines include the study of structure-properties relationship in new magnetic, multiferroic and magnetoelectric materials with special charge, spin or electronic orders, and the study of novel oxides with giant responses for information technologies. In addition to bulk materials and films, surface diffraction synchrotron techniques and surface characterization methods are applied to the study of ordering related phenomena in low-dim systems and interfaces.

Members

  • Prof. José Luis García-Muñoz - Research Professor
  • Dr. Xavier Torrelles - Research Scientist
  • Dr. Javier Herrero Martín – Collaborator (ALBA)
  • Dr. Vassil Skumryev – Collaborator (UAB, ICREA)
  • Xiaodong Zhang – Graduate Researcher
  • Arnau Romaguera – Graduate Researcher
  • Adrián Crespo Villanueva – Graduate Researcher

A: Long single-crystal of a layered spiral MF grown by TS-FZ. Magnetoelectric effect proved by polarized RXMS in the spiral phase of a (Mn,Co)WO4 multiferroic crystal.
B: YBaCuFe1-xMnxO5 multiferroics: Tilting the spiral rotation plane (θ) by increasing the Mn content. Projections of the spiral magnetic order at 10K. Evolution of the inclination angle θ of the spins (easy-axis) in the spiral and collinear regimes.
C: Anatase-(001) crystals grown by PLD (top, AFM) and MBE (middle, STM). Thickness ~8 nm, lateral size larger than 50 nm. Bottom picture is a zoom of the middle one showing atomic resolution.

Achievements

Among the novel properties realized in chiral magnetic systems the multiferroicity is one of the most attractive. Most of the chiral magnetoelectric multiferroics investigated in recent years are geometrically frustrated magnets. An exception are the layered perovskites LnBaCuFeO5, one of the most promising chiral multiferroics for ambient temperature applications. In samples prepared in polycrystalline and single-crystal form we have thoroughly investigated the close relationship between Fe/Cu chemical disorder and the stability and properties of its spiral magnetic order (TS). A triple-point was reached in YBaCuFeO5 compounds limiting the maximum TS to ~370K in absence of external perturbations.

Within the context of optimization and upgrade of high-temperature spiral multiferroics, we also tackled the effects of increasing the spin-orbit coupling in these layered perovkites by introducing less symmetric Mn3+ ions (L=2, S=2) at the B site. We proved that the tilt of the rotation plane of the spins in the spiral phase can be tuned by the presence of Mn, which can transform a helix-type magnetic order into a cycloidal-type spiral.

The latter being more favorable for generating ferroelectricity. Other activities focused on potential hybrid multiferroics, and elastic, charge and spin coupled transitions in frustrated oxides. One of the most interesting systems for photovoltaic conversion of light to electricity is Titania. Since its efficiency is related with the atomic coordination of the topmost Ti-atoms at the surface, anatase is a good model system. However anatase crystals cannot be artificially synthesized, its most active surface being the most unstable.

Among our activities on titania film synthesis we have grown anatase-TiO2(001) surfaces in the form of TiO2 films by PLD and MBE in UHV with enough quality and cleanliness to be used for Surface Science purposes. The explored range of film thicknesses goes from few nm (MBE) to more than one hundred (PLD).

Publications

Tuning the tilting of the spiral plane by Mn doping in YBaCuFeO5 multiferroic
X. Zhang, A. Romaguera, O. Fabelo, F. Fauth, J. Herrero-Martín and J.L. García-Muñoz
Acta Materialia 2020 206, 116608, 10.1016/j.actamat.2020.116608

Magnetic properties of Cr-substituted epsilon-(Fe1-xCrx)(2)O-3 nanoparticles with epsilon structure
Ma, Zheng; Romaguera, Arnau; Fauth, Francois; Herrero-Martin, Javier; Luis Garcia-Munoz, Jose; Gich, Marti
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 2020 506, 166764, 10.1016/j.jmmm.2020.166764

Ferromagnetic and antiferromagnetic resonances in ε-Fe2O3
Z. Ma, V. V K Thalakkatukalathil, A. Romaguera, J. L. García-Muñoz, F. Macià, J. M. Hernandez, M. Gich
Proc. of the 16èmes Journées de Caractérisation Microondes et Matériaux, Toulouse 2020

Structural study of decrespignyite-(Y), a complex yttrium rare earth copper carbonate chloride, by three-dimensional electron and synchrotron powder diffraction
Rius, Jordi; Colombo, Fernando; Vallcorba, Oriol; Torrelles, Xavier; Gemmi, Mauro; Mugnaioli, Enrico
EUROPEAN JOURNAL OF MINERALOGY 2020, 32, 5, 545-555, 10.5194/ejm-32-545-2020

Structure and phase transitions in A-site ordered RBaMn2O6 (Pr, Nd) perovskites with a polar groundstate
J. Blasco, G. Subías, M. L. Sanjuán, J. L. García-Muñoz, F. Fauth and J. García
Phys. Rev. B 2020, 103, 064105, 10.1103/PhysRevB.103.064105

Outreach activities

  • Participation in the Organizing Committee of the digital “Jornada Otoñal de la Sociedad Española de Técnicas Neutrónicas” (11/2020)

  • Participation in the 1st ALBA-ICMAB Workshop with the oral presentations “Multiferroics and more” and “Characterization of ordered bulk/film magnetic materials for RT applications using Boreas” (02/2020)

  • Participation in the Organizing Committee of the “SETN Seminar Series 2020-21” (videoconference series)

Awards&Recognitgions

  • Introduction as a national representative of the Spanish Association of Synchrotron Users in the European Synchrotron and FEL User Organisation (ESUO): J.L. Garcia-Muñoz
  • Introduction as a member of the Scientific Panel of the ALBA-Synchrotron Light Source: Chemistry&Materials Science Panel: J.L. Garcia-Muñoz

Main projects

Investigation of complex oxides for ferroelectric and magnetic applications (ICOFEMA)
Programa I+D+i Orientada a los Retos de la Sociedad RTI2018-098537-B-C21
J. L. García Muñoz
2019-2021

Trans-pyrenean node for scientific instrumentation
Fondo Europeo de Desarrollo Regional (FEDER). POCTEFA 2014-2020. Programa INTERREG V-A España-Francia-Andorra EFA194/16 TNSI
X. Torrelles
2014-2020

Coordination
Anna May-Masnou This email address is being protected from spambots. You need JavaScript enabled to view it.
Redaction
Anna May-Masnou This email address is being protected from spambots. You need JavaScript enabled to view it.
Web & Graphic Editor
José Antonio Gómez  This email address is being protected from spambots. You need JavaScript enabled to view it.

Webmasters
José Antonio Gómez This email address is being protected from spambots. You need JavaScript enabled to view it.
Albert Moreno     This email address is being protected from spambots. You need JavaScript enabled to view it.
ICMAB