Research Groups

RESEARCH UNIT: Magnetic Materials and Functional Oxides

Advanced Characterization and Nanostructuration of Materials (ACNM)

Research of the group has concentrated on the study of spin dependent transport properties in ferromagnetic oxide/normal metal heterostructures. Generation of pure spin currents, by spin pumping, and detection of inverse spin Hall effect voltage signals, separated from spurious spin rectification effects have been accomplished. Spin Hall magnetoresistance has also been used to study interfacial magnetic properties.

The Advanced Characterization and Nanostructuration of Materials (ACNM) group’s main scientific goal is to generate both fundamental and applied knowledge for the implementation of functional oxide materials in novel technologies as spintronics.

The group focuses on the preparation and advanced characterization of thin films and nanostructures of complex oxides with potential functional properties of interest for the development of magnetoelectronic devices with new and enhanced performances.

The main research line is focused on the use of the spin of electrons as a control variable for the implementation on spintronic devices. Additionally, resistive switching phenomena and self-assembling processes in functional oxides and preparation and characterization of magnetic nanoparticles for life sciences are also investigated.

Members

  • Prof. Benjamín Martínez - Research Professor
  • Dr. Lluís Balcells - Research Scientist
  • Dr. Felip Sandiumenge - Research Scientist
  • Dr. Carlos Frontera - Tenured Scientist
  • Dr. Alberto Pomar - Tenured Scientist
  • Sergi Martín - PhD Researcher
  • Mónica Bernal - PhD Researcher
  • Víctor Fuentes - PhD Researcher

Left: Upper part: Transversal voltage signal measurements in Si// Py/Pt samples for different values of L as a function of the applied magnetic field. Dependence of the amplitude of the symmetric component of the transversal voltage signal of each sample set at room temperature as a function of sample width, L. Lower part: Rectification voltage calculated by expression (B13), (a) plots the expected contribution to V of AMR (divided by Δρ in A/m) and (b) that from AHE (divided by ρAHE in A/m). Panel (c) plots the same quantities averaged over the film thickness. All parameters used for the calculations, except H0, are the same that in Fig. B2. It is worth noting that the sign convention in this figure is the opposite to that in Figs. 2a, 3a, 4a, and 5a.

Right: Contact Potential Difference (CPD) map measured in the SIO-214 thin film after applying a voltage of 6 V to an inner square of 20 Å~ 20 μm2 (i.e., erasing into HRS state) in a previously written sample as in Fig. 5. (b) CPD profile showing the difference between pristine (taken as reference), LRS and HRS states.

Achievements

The research interest of the group is twofold and focus on the preparation of high-quality complex oxide epitaxial thin films and on the advanced characterization of their magnetic and electronic transport properties. During this year we have proceeded with our work on the preparation of double perovskite thin films by polymer assisted deposition (PAD) techniques. The relevance of the annealing processes on the preparation of epitaxial films prepared by chemical solution deposition methods has been analyzed making evident how parameters, such as the heating ramp speed, may have strong influence in the final magnetic properties of the samples.

On the other hand, the work of the group has been mainly addressed to the study of spin dependent transport properties in ferromagnetic oxide/normal metal heterostructures. In particular, big efforts have concentrated in the generation and detection of pure spin currents by spin pumping and inverse spin Hall effect (ISHE) respectively. An important problem in spin pumping experiments in ferromagnetic and metallic (FM) systems is the appearance of spin rectification effects (SRE) due to the inductive coupling between the sample and the signal line of the coplanar waveguide (CPW) used to bring the RF excitation signal. Disentangle pure spin currents from parasitic effects due to SRE is a difficult task that is seriously hampering the implementation of SP in spin devices. We have developed a strategy that allows disentangling SRE and ISHE contributions to the transversal voltage signal measured in SP experiments in FM/normal metal (NM) bilayers.

The effectiveness has been proved in the permalloy (Py)/Pt system demonstrating that SRE in SP experiments, using a CPW or microstrip experimental setup, can be fully suppressed by reducing the width of the sample along the CPW signal line. At the same time, the group has also proceeded with the studies of reversible resistive switching (RS) phenomena, i.e. the change of resistance in a reversible manner between two stable states of well-defined resistance by applying voltage pulses. We have studied the local electrical properties, measured by conductive atomic force microscopy, of semimetallic SrIrO3 thin films demonstrating the appearance of an Anderson-type metal−insulator transition triggered by disorder and spatial localization due to film thickness reduction. For thin enough films (below ∼3 nm) samples are insulating with hysteretic I−V curves indicative of reversible resistive switching behavior between two states of clearly different resistance at room temperature.

Publications

Temperature dependence of spin pumping and inverse spin Hall effect in permalloy/Pt bilayers
Martin-Rio, S.; Pomar, A.; Balcells, Ll; Bozzo, B.; Frontera, C.; Martinez, B.
Journal of Magnetism and Magnetic Materials 2020, 500, 166319, 10.1016/j.jmmm.2019.166319

Resistive switching in Strontium iridate based thin films
Fuentes, Victor; Vasic, Borislav; Konstantinovic, Zorica; Martinez, Benjamin; Balcells, Lluis; Pomar, Alberto
Journal of Magnetism and Magnetic Materials 2020, 501, 166419, 10.1016/j.jmmm.2020.166419

Rapid Thermal Annealing of Double Perovskite Thin Films Formed by Polymer Assisted Deposition
Wang, Hailin; Frontera, Carlos; Martinez, Benjamin; Mestres, Narcis
Materials 2020, 13, 21, 4966, 10.3390/ma13214966

Aqueous Chemical Solution Deposition of Functional Double Perovskite Epitaxial Thin Films
Wang, Hailin; Frontera, Carlos; Herrero-Martin, Javier; Pomar, Alberto; Roura, Pere; Martinez, Benjamin; Mestres, Narcis
Chemistry - A European Journal 2020, 26, 42, 9338-9347, 10.1002/chem.202000129

Self-assembled line network in BiFeO3 thin films
Colson, B.; Fuentes, V; Konstantinovic, Z.; Colson, D.; Forget, A.; Lazarevic, N.; Scepanovic, M.; Popovic, Z., V; Frontera, C.; Balcells, Ll; Martinez, B.; Pomar, A.
Journal of Magnetism and Magnetic Materials 2020, 509, 166898, 10.1016/j.jmmm.2020.166898

Controlling Magnetization Reversal and Hyperthermia Efficiency in Core–Shell Iron–Iron Oxide Magnetic Nanoparticles by Tuning the Interphase Coupling
K. Simeonidis, C. Martinez-Boubeta, D. Serantes, S. Ruta, O. Chubykalo-Fesenko, R. Chantrell, J. Oró-Solé, Ll. Balcells, A. S. Kamzin, R. A. Nazipov, A. Makridis, and M. Angelakeris
ACS Appl. Nano Mater. 2020, 3, 4465, 10.1021/acsanm.0c00568

Awards&Recognitgions

Appointment of a member of the evaluation committee of the 2020 call of RISE: H2020-MSCA-RISE: Alberto Pomar
Coordination
Anna May-Masnou This email address is being protected from spambots. You need JavaScript enabled to view it.
Redaction
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Web & Graphic Editor
José Antonio Gómez  This email address is being protected from spambots. You need JavaScript enabled to view it.

Webmasters
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