Research Groups

RESEARCH UNIT: Magnetic Materials and Functional Oxides

Laboratory of Multifunctional Thin Films and Complex Structures (MULFOX)

The group has made an enormous progress on the growth and characterization of epitaxial ferroelectric (Hf, Zr)O2 films, high polarization and reliability has been achieved in sub-5 nm films, and the disclosure of switchable electroresistance down to few nanometers. Photoresponsive polar materials have evolved into a major axis of research and photoresponsive 2DEGs, that mimic synaptic spike-timing dependent plasticity, have been discovered. New developments encompass flexible antiferromagnets.

The Laboratory of Multifunctional Thin Films and Complex Structures (MULFOX) focuses on the development and integration of new materials, especially nanometric oxide thin films, and the exploration of their use in photovoltaics, photonics, electronics, spintronics, data storage and computing. These broad and scientifically challenging objectives are currently major technological demands, as silicon-based electronics is reaching its limits and radically new and sustainable approaches are needed.

Specifically, current activities include: the search for disruptive approaches to materials and methods in photovoltaic conversion and transparent metals; development of materials and devices that, based on polar materials, may allow us to contribute to develop more efficient data storage and brain-inspired computing schemes; exploring data storage and data manipulation alternatives to current methods, by using non-dissipative currents or efficient plasmonic signals and integration of functional (magnetic and ferroelectric) materials in photonic devices.


  • Prof. Josep Fontcuberta - Research Professor
  • Dr. Lourdes Fàbrega - Tenured Scientist
  • Dr. Florencio Sánchez - Tenured Scientist
  • Dr. Gervasi Herranz - Tenured Scientist
  • Dr. Vassil Skumryev - ICREA Research Professor – UAB
  • Dr. Mikko Kataja - Postdoctoral Researcher
  • Dr. Ferran Macià - Postdoctoral Researcher
  • Dr. Ignasi Fina - Postdoctoral Researcher (Ramon y Cajal)
  • Tingfeng Song - PhD Researcher
  • Yunwei Sheng - PhD Researcher
  • Xiao Long - PhD Researcher
  • Milena Sulzbach - PhD Researcher
  • Mathieu Mirjolet - PhD Researcher
  • Yu Chen - PhD Researcher
  • Saul Estandía - PhD Researcher
  • Jiahui Jia - PhD Researcher
  • Manel Mas Martí - PhD Researcher
  • Tetiana Zakusylo - Master Student
  • Clemens Lindermeir - Undergraduate Student
  • Francisco Fernández Comino - Undergraduate Student
  • Roger Silvestre - Undergraduate Student
  • Hector Fernández - Undergraduate Student

a) Channels along grain boundaries between orthorhombic and monoclinic crystallites (o-HZ) and (m-HZO) in Hf0.5Zr0.5O2 (HZO) thin films are responsible for an ionic-like electroresistive channel competing with ferroelectric resistive switching. Capping HZO films with an ultrathin dielectric layer allows suppression of ionic electroresistance. b) STEM image showing the coexistence of o-HZ and m-HZO in a HZO film. c) High crystalline quality sub-5 nm Hf0.5Zr0.5O2 capacitors, integrated epitaxially with Si(001), present high polarization, endurance and retention. d) Different magnetic state of FeRh depending on the strain. If compressive, antiferromagnetism is favored. Background: representation of the "nanoneedle" pressing the surface of the iron-rhodium alloy, causing the magnetic state of the materials to change. By pressing, antiferromagnetic nano-islands are created embedded in a ferromagnetic matrix. e) The conductance of the LaAlO3/SrTiO3 interfaces can be changed by optical pulses: blue-violet pulses increase the population of the quantum well (accumulation), while red light pulses decrease it (depletion). The resulting wavelength-dependent photoconductance enables to mimic the functionality of spiking-timing-dependence plasticity (STDP) using light as stimulus. f) Pulses of individual X-ray photons detected, using a Mo/Au Transition Edge Superconductor sensor (background image). g) Voltage controlled electronic orbital occupancy in LaNiO3 films.


The group has focused on the development of epitaxial ferroelectric Hf0.5Zr0.5O2 (HZO) and related compositions aiming at controlling the presence of the different polymorphs of HZO, reducing leakage and improving endurance, retention and polarization. HZO films of thickness less than 5 nm, presenting high polarization, endurance and retention, have been integrated epitaxially with Si(001). It has been found that tunnel junctions of HZO display a large electroresistance directly related to polarization switching, which is entangled with ionic-like electroresistance mechanisms when ferroelectric and non-ferroelectric phases of HZO coexist, as evidenced by detailed electron microscopy studies. Strategies to mitigate these detrimental effects have been successfully demonstrated. In the quest for novel ferroelectric materials, MULFOX has largely collaborated with external groups on the characterization of materials and contribute to the discovery of new families (i.e BaWON2) or to achieve a deep understanding of polarization reversal in uncommon ferroelectrics (-Fe2O3). In the quest to exploit photoresponsive tunnel junctions, new experimental facilities are being developed. First output is the demonstration of persistent photocurrents associated to quantum wells at polar interfaces, which have shown neuromorphic-like response. The use of ferroelectrics for pattern recognition has been also demonstrated.

Magnetic materials have been investigated from a double perspective. On one hand, we have pursued the research on spin conductance across interfaces between ferromagnetic insulators thin films and heavy metals, now focusing on Pd, aiming at minimizing the Stoner instability. On the other hand, progress on understanding antiferromagnetic-ferromagnetic alloys (i.e FeRh) has been reviewed and novel applications, including flexible memories are being developed.

The strong collaboration with ALBA has been instrumental to develop a new experimental set up, now installed at BOREAS beam-line of ALBA, allowing to perform X-ray absorption experiments under electric stimulus. We have used this new facility to demonstrate the in-operando control of electron occupation of atomic orbitals on transition metal oxide thin films (LaNiO3). We have successfully developed single photon detectors based on transition-edge sensors, with applications in astrophysics, dark matter search and quantum sensing.


Enhancement in Thermally Generated Spin Voltage at the Interfaces between Pd and NiFe2O4 Films Grown on Lattice-Matched Substrates
Rastogi, A.; Li, Z.; Singh, A., V; Regmi, S.; Peters, T.; Bougiatioti, P.; Meier, D. Carsten ne; Mohammadi, J. B.; Khodadadi, B.; Mewes, T.; Mishra, R.; Gazquez, J.; Borisevich, A. Y.; Galazka, Z.; Uecker, R.; Reiss, G.; Kuschel, T.; Gupta, A.
PHYSICAL REVIEW APPLIED 2020, 14, 1, 14014, 10.1103/PhysRevApplied.14.014014

Embedded Magnetism in YBa2Cu3O7 Associated with Cu-O Vacancies within Nanoscale Intergrowths: Implications for Superconducting Current Performance
Bartolome, Elena; Mundet, Bernat; Guzman, Roger; Gazquez, Jaume; Manuel Valvidares, S.; Herrero-Martin, Javier; Pellegrin, Eric; Puig, Teresa; Obradors, Xavier
ACS APPLIED NANO MATERIALS 2020, 3, 3, 3050-3059, 10.1021/acsanm.0c00505

Local strain-driven migration of oxygen vacancies to apical sites in YBa2Cu3O7-x
Mundet, Bernat; Hartman, Steven T. T.; Guzman, Roger; Idrobo, Juan C. C.; Obradors, Xavier; Puig, Teresa; Mishra, Rohan; Gazquez, Jaume
NANOSCALE 2020, 12, 10, 5922-5931, DOI: 10.1039/d0nr00666a

An Atomic-Scale Perspective of the Challenging Microstructure of YBa2Cu3O7−x Thin Films
Mundet, R. Guzmán, E. Bartolomé, A. R Lupini, S. Hartman, R. Mishra, J. Gázquez
Superconductivity 2020, 189-212, 10.1007/978-3-030-23303-7_7

Epitaxial Ferroelectric La-Doped Hf0.5Zr0.5O2 Thin Films
Song, Tingfeng; Bachelet, Romain; Saint-Girons, Guillaume; Solanas, Raul; Fina, Ignasi; Sanchez, Florencio
ACS APPLIED ELECTRONIC MATERIALS 2020, 2, 10, 3221-3232, 10.1021/acsaelm.0c00560

Thermal evolution of ferroelectric behavior in epitaxial Hf0.5Zr0.5O2
Adkins, J. W.; Fina, I.; Sanchez, F.; Bakaul, S. R.; Abiade, J. T.
APPLIED PHYSICS LETTERS 2020, 117, 14, 142902, 10.1063/5.0015547

Non-linear temperature dependent phononic response of epitaxial lanthanum nickelate thin film
Sunidh; Sharma, Vishal; Arora, Sunil K.; Sanchez, Florencio; Sathe, Vasant
SOLID STATE COMMUNICATIONS 2020, 321, 114038, 10.1016/j.ssc.2020.114038

Fatigue and retention in the growth window of ferroelectric Hf0.5Zr0.5O2 thin films
Lyu, Jike; Fina, Ignasi; Sanchez, Florencio
APPLIED PHYSICS LETTERS 2020, 117, 7, 72901, 10.1063/5.0017738

High polarization, endurance and retention in sub-5 nm Hf0.5Zr0.5O2 films
Lyu, Jike; Song, Tingfeng; Fina, Ignasi; Sanchez, Florencio
NANOSCALE 2020, 12, 20, 11280-11287, 10.1039/d0nr02204g

Blocking of Conducting Channels Widens Window for Ferroelectric Resistive Switching in Interface-Engineered Hf(0.5)Zr(0.5)O(2)Tunnel Devices
Sulzbach, Milena Cervo; Estandia, Saul; Gazquez, Jaume; Sanchez, Florencio; Fina, Ignasi; Fontcuberta, Josep
ADVANCED FUNCTIONAL MATERIALS 2020, 30-32, 2002638 10.1002/adfm.202002638

Domain-Matching Epitaxy of Ferroelectric Hf0.5Zr0.5O2(111) on La2/3Sr1/3MnO3(001)
Estandia, Saul; DIx, Nico; Chisholm, Matthew F.; Fina, Ignasi; Sanchez, Florencio
CRYSTAL GROWTH & DESIGN 2020, 20, 6, 3801-3806 10.1021/acs.cgd.0c00095

Flexible Antiferromagnetic FeRh Tapes as Memory Elements
Fina, Ignasi; Dix, Nico; Menendez, Enric; Crespi, Anna; Foerster, Michael; Aballe, Lucia; Sanchez, Florencio; Fontcuberta, Josep
ACS APPLIED MATERIALS & INTERFACES 2020, 12, 13, 15389-15395, 10.1021/acsami.0c00704

Unconventional Ferroelectric Switching via Local Domain Wall Motion in Multiferroic epsilon-Fe2O3 Films
Guan, Xiangxiang; Yao, Lide; Rushchanskii, Konstantin Z.; Inkinen, Sampo; Yu, Richeng; Lezaic, Marjana; Sanchez, Florencio; Gich, Marti; van Dijken, Sebastiaan
ADVANCED ELECTRONIC MATERIALS 2020, 1901134, 10.1002/aelm.201901134

Unraveling Ferroelectric Polarization and Ionic Contributions to Electroresistance in Epitaxial Hf0.5Zr0.5O2 Tunnel Junctions
Cervo Sulzbach, Milena; Estandia, Saul; Long, Xiao; Lyu, Jike; Dix, Nico; Gazquez, Jaume; Chisholm, Matthew F.; Sanchez, Florencio; Fina, Ignasi; Fontcuberta, Josep
ADVANCED ELECTRONIC MATERIALS 2020, 6, 1, 1900852, 10.1002/aelm.201900852

Optical second harmonic generation from LaAlO3/SrTiO3 interfaces with different in-plane anisotropies
Rubano, Andrea; Scigaj, Mateusz; Sanchez, Florencio; Herranz, Gervasi; Paparo, Domenico
JOURNAL OF PHYSICS-CONDENSED MATTER 2020, 32, 13, 135001, 10.1088/1361-648X/ab5ccc

Engineering Polar Oxynitrides: Hexagonal Perovskite BaWON2
Oro-Sole, Judith; Fina, Ignasi; Frontera, Carlos; Gazquez, Jaume; Ritter, Clemens; Cunquero, Marina; Loza-Alvarez, Pablo; Conejeros, Sergio; Alemany, Pere; Canadell, Enric; Fontcuberta, Josep; Fuertes, Amparo
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 2020, 59, 42, 18395-18399, 10.1002/anie.202006519

Discovery of highly polarizable semiconductors BaZrS3 and Ba3Zr2S7
Filippone, Stephen; Zhao, Boyang; Niu, Shanyuan; Koocher, Nathan Z.; Silevitch, Daniel; Fina, Ignasi; Rondinelli, James M.; Ravichandran, Jayakanth; Jaramillo, R.
PHYSICAL REVIEW MATERIALS 2020, 4, 9, 91601, 10.1103/PhysRevMaterials.4.091601

Local manipulation of metamagnetism by strain nanopatterning
Foerster, Michael; Menendez, Enric; Coy, Emerson; Quintana, Alberto; Gomez-Olivella, Carles; Esque de los Ojos, Daniel; Vallcorba, Oriol; Frontera, Carlos; Aballe, Lucia; Nogues, Josep; Sort, Jordi; Fina, Ignasi
MATERIALS HORIZONS 2020, 7, 8, 2056-2062, 10.1039/d0mh00601g

Strain and voltage control of magnetic and electric properties of FeRh films
Fina, Ignasi; Fontcuberta, Josep
JOURNAL OF PHYSICS D-APPLIED PHYSICS 2020 53, 2, 023002, 10.1088/1361-6463/ab4abd

Magnetic and ferroelectric properties, crystal and magnetic structures of SrFe11.9In0.1O19
Turchenko, V. A.; Trukhanov, A.; Trukhanov, S.; Damay, F.; Porcher, F.; Balasoiu, M.; Lupu, N.; Chiriac, H.; Bozzo, B.; Fina, I; Waliszewski, J.; Kostishyn, V. G.; Recko, K.; Polosan, S.
PHYSICA SCRIPTA 2020, 95, 4, 44006, 10.1088/1402-4896/ab60fb

Vehicle classification system based on ferroelectric materials.
I. Fina, X. Martí, G. Catalan.
2019 IEEE International Symposium on Applications of Ferroelectrics (ISAF) 2020, 10.1109/ISAF43169.2019.9034960

Photoinduced Persistent Electron Accumulation and Depletion in LaAlO3/SrTiO3 Quantum Wells
Chen, Yu; Lechaux, Yoann; Casals, Blai; Guillet, Bruno; Minj, Albert; Gazquez, Jaume; Mechin, Laurence; Herranz, Gervasi
PHYSICAL REVIEW LETTERS 2020, 124, 24, 246804, 10.1103/PhysRevLett.124.246804

In operando adjustable orbital polarization in LaNiO3 thin films
Vasili, Hari Babu; Pesquera, David; Valvidares, Manuel; Gargiani, Pierluigi; Pellegrin, Eric; Bondino, Federica; Magnano, Elena; Barla, Alessandro; Fontcuberta, Josep
PHYSICAL REVIEW MATERIALS 2020, 4, 4, 44404, 10.1103/PhysRevMaterials.4.044404

AC/DC Characterization of a Ti/Au TES with Au/Bi Absorber for X-ray Detection
Taralli, E.; Pobes, C.; Khosropanah, P.; Fabrega, L.; Camon, A.; Gottardi, L.; Nagayoshi, K.; Ridder, M. L.; Bruijn, M. P.; Gao, J. R.
JOURNAL OF LOW TEMPERATURE PHYSICS 2020, 10.1007/s10909-020-02390-w

Understanding the basic components of the Universe, its structure and evolution
Costa, María José ; Schödel, Rainer; Heinemeyer, Sven ; Calderon, Alicia ; Casas, Alberto ; Vicente, Avelino ; Hernández Gamazo, Pilar ; Tolós, Laura; Vilar, Rocío ; Crocce, Martín ; Vílchez Medina, José Manuel ; Mas-Hesse, J. Miguel ; Najarro, Francisco ; Goicoechea, Javier R. ; Ortín Miguel, Tomás ; Calcagni, Gianluca ; Lacasta Llácer, Carlos ; Fàbrega, Lourdes ; Enciso, Alberto; Marchesano, Fernando ; Rea, Nanda ; Pérez-Torres, Miguel A
Libro Blanco CSIC 9 2020, 10.20350/digitalCSIC/12656

Outreach activities

Organization of the OPTOFEM 2020 ICMAB Summer School on Optically Controlled Ferroelectric Memrisors by Josep Fontcuberta and Ignasi Fina

Participation on the Ciclo de Seminarios del Laboratorio de Resonáncias Magnéticas CAB-CNEA Bariloche (Argentina): “In-operando adjustable orbital polarization in LaNiO3 thin films” (27/10/2020) by Josep Fontcuberta

Participation on the Physics Colloquium at the University of Leipzig with ”From transparent metals to magnetics. Electron filling in transitions metal oxides holds the key" (17/11/2020) by Josep Fontcuberta

Talk to ESO students at the Escola Santa Maria, Blanes (03/02/2020 and 14/02/2020) by Lourdes Fábrega

Main projects

Oxide responses inspired on nature (ORION)
Spanish Ministry of Economy, Industry and Competitiveness, AT2017-85232-R
F. Sánchez, G. Herranz
2018-2021 // 242.000€

Detectores de rayos X basados en TES: optimización del pixel y desarrollo de arrays
Spanish Ministry of Economy, Industry and Competitiveness, RTI2018-096686-B-C22
Lourdes Fàbrega
01/2019 - 12/2021

Integrated Activities in the High Energy Astrophysics Domain
Lourdes Fàbrega
03/2020 - 02/2024

Escritura óptica en memorias ferroeléctricas túnel para dispositivos neuromórficos de visión (OPTIFERRO)
Becas Leonardo a Investigadores y Creadores Culturales - Fundación BBVA 2020
Ignasi Fina
11/2020 - 5/2022 // 38.500€

ENERGY-efficient and industrially-compatibe MULTIferroic materials (MultiEnergy)
Ministerio de Ciencia, Innovación y Universidades, PID2019-107727RB-I00
Ignasi Fina
6/2020- 12/2023 // 60.500€

Improved security magnetic memory device (ISMEM)
Generalitat de Catalunya - AGAUR, 2019 LLAV 00050
Josep Fontcuberta
9/2020- 5/2021 // 20.000€

Anna May-Masnou This email address is being protected from spambots. You need JavaScript enabled to view it.
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.

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.