ISrTiO3-based conducting interfaces, which exhibit coexistence of gate-tunable 2D superconductivity and strong Rashba spin-orbit coupling (RSOC), are candidates to host topological superconductive phases. Yet, superconductivity is usually in the dirty limit, which tends to suppress nonconventional pairing and therefore challenges these expectations. Here we report on LaAlO3/SrTiO3 (LAO/STO) interfaces with large mobility and mean free paths comparable to the superconducting coherence length, approaching the clean limit for superconductivity. We further show that the carrier density, mobility, and formation of the superconducting condensate are controlled by the fine-tuning of La/Al chemical ratio in the LAO film. We find a region in the superconducting phase diagram where the critical temperature is not suppressed below the Lifshitz transition, at odds with previous experimental investigations. These findings point out the relevance of achieving a clean-limit regime to enhance the observation of unconventional pairing mechanisms in these systems.

E. Longo et al. Giant Spin-Charge Conversion in Ultrathin Films of the MnPtSb Half-Heusler Compound. Advanced Functional Materials 2407968 (2024)

DOI: https://doi.org/10.1002/adfm.202407968

Abstract:

Half-metallic half-Heusler compounds with strong spin-orbit-coupling and broken inversion symmetry in their crystal structure are promising materials for generating and absorbing spin-currents, thus enabling the electric manipulation of magnetization in energy-efficient spintronic devices. In this work, we report the spin-to-charge conversion in the sputtered half-Heusler MnPtSb within thickness (t) range from 1 to 6 nm. A combination of X-ray and transmission electron microscopy measurements evidence the epitaxial nature of these ultrathin non-centrosymmetric layers, with a clear (111)-orientation on top of (0001) single-crystal sapphire. By broadband ferromagnetic resonance (FMR), we observe a four orders of magnitude tunable spin accumulation in the MnPtSb-based heterostructures, within t=1-6 nm range. By using spin pumping FMR, we measure a remarkable t-dependent spin-charge conversion in the MnPtSb layers, which clearly demonstrates the interfacial origin of the conversion. When interpreted within the inverse Edelstein effect (IEE), the spin-charge conversion efficiency extracted at room temperature for the thinnest MnPtSb layer reaches λIEE~3 nm, representing an extremely high conversion at room temperature. The still never explored ultrathin regime of the MnPtSb films studied in this work and the discovery of their outstanding functionality are two ingredients which demonstrate the potentiality of such materials for future applications in spintronics. 

Dr. Gyanendra Singh has delivered the talk “Signature of unconventional superconductivity in 2D oxide interfaces” in the symposium T1.01 Unconventional superconductivity and magnetism in SCES VI at the International Conference on Magnetism 2024, held in Bologna, Italy.

Dr. Jaume Gazquez has delivered the talk “Large photoresponse, strain and grain boundaries of LaFeO₃-based heterojunctions” in the Workshop Advanced Electron Microscopy For Advanced Materials, held in Wuzhen, China.

Prof. Kyle Shen, from the Department of Physics at Cornell University, deliveres a talk at ICMAB entitled “Thin Film Nickelates: A New Frontier for High-Temperature Superconductivity”.

Here the abstract about the talk:

Superconductivity plays a key role in many next-generation technologies, including quantum computing and sensing. The promise of discovering new superconductors with higher transition temperatures has been at the forefront of research in condensed matter physics, materials science, and solid state chemistry for the past 4 decades. From the high-temperature cuprate superconductors of the 1990s, to the iron-based superconductors of the 2010s, significant attention has now been directed in the past few years to the nickelate families of superconductors, particularly the so-called “infinite layer” nickelates as well as the recently discovered bilayer nickelate, La₃Ni₂O₇.

In this seminar, I will describe recent advances in the study of the infinite-layer and bilayer nickelate superconductors. I will highlight new thin film synthesis approaches developed by our research group, and how this enables investigations of superconductivity and the phase diagram of both these families.

Dr. Emanuele Longo has delivered the talk “Possible orbital momentum accumulation in the SrVO3 light early transition metal oxide” in the Symposium T3.03 Spin-orbit effects and spin-charge-orbit conversion phenomena II at the International Conference on Magnetism 2024, held in Bologna, Italy. 

MULFOX’ PhD Student Mario Villa contributed with two oral presentations entitled “Large photoresponse and grain boundaries of LaFeO₃-based heterojunctions” and “Microstructural domain mapping of LaFeO₃-based heterojunctions” within the Advanced PV material characterization and Analytical techniques for accurate nanoscale characterization of advanced materials symposiums respectively during the EMRS Spring meeting held in Strasbourg, France during May, 2024. 

We are pleased to announce that Gyanendra Singh and Gervasi Herranz will be delivering invited talks at the 7th International Workshop on Complex Oxides in Cargèse, Corsica. Gyanendra Singh will discuss “Stoichiometric Control of 2D Superconductivity and Mobility at SrTiO3-Based Interfaces,” while Gervasi Herranz will present on “Spin-Orbit Entanglement Driven by the Jahn-Teller Effect.” Join us for these insightful sessions on groundbreaking research in complex oxides!

The School was held on 30 and 31 May 2024, and had a participation of 150 attendants, among them 36 in-person and 114 online.

The school included a seminar on “Signatures of a spin-orbital chiral metal” by Mario Cuoco on 29th May. It was followed by lectures on 30th and 31th May by Annika Johansson, Andrea Caviglia and Mario Cuoco, which motivated lively discussions, comments and suggested intriguing prospectives.

Karla Mena, Martí Ramis, Mariona Coll and former member of the team Pol Sallés participated at the EMRS Spring meeting held in Strasburg May 2024
Karla Mena presented an oral contribution on multiferroic composites for energy harvesting, Martí Ramis presented a poster on nanomechanical properties of manganite membranes on plastic substrates, Mariona Coll delivered an invited talk on the opportunities of chemical methods to prepare freestanding complex oxide membranes and Pol Sallés presented an invited talk on the challenges to prepare BiFeO₃ membranes by chemical solution deposition.

Dr. Takayuki Shiino and Dr. Weronika Janus joined MULFOX as postdoctoral researchers, and Teodor Apetrei joined as a Ph.D. candidate. We warmly welcome them to the group and wish them success.

Takayuki received his BSc in Physics (2013) and MSc in Materials Science and Engineering (2016) from Tokyo Institute of Technology (Japan) and KAIST (South Korea), respectively. He received his Ph.D. from Nagoya University (Japan) in 2019 with a thesis on a quantum critical phenomenon in heavy-fermion materials. After the PhD, he experienced two postdoctoral researches: Uppsala University (2019 – 2021, Sweden) and KAIST (2022 – 2024, South Korea) for the studies of quasicrystals and spintronics, respectively. His postdoctoral research at MULFOX focuses on spintronic devices with insulating ferrimagnetic materials.

Weronika studied at AGH University of Krakow, Poland, where she obtained her BSc in Biomedical Engineering (2018), MSc in Biomedical Engineering – Bionanotechnology (2019), and PhD in Physics (2014). During her PhD, she focused on the strain manipulation of magnetic properties in antiferromagnetic thin films. Her current research interest is in developing innovative magnetic insulator-based spintronic memory devices, where the information can be written and read by all-electrical means

Teodor obtained his BSc. degree in Computational Physics at University Alexandru Ioan Cuza Iasi (Romania, 2020) and his MSc. degree in Applied and Engineering Physics at Technische Universitat Munchen (Germany, 2023). The main focus of his current research is the growth and engineering of magnetic oxide and nitride thin films by magnetron sputtering with tunable interfacial chiral magnetism and perpendicular anisotropy.

This is the 3rd Edition of “ICMAB Schools on Frontiers in Materials Science and Condensed Matter”. Previous editions were “Angle Resolved Photoemission Spectroscopy (https://arpes2023.icmab.es/)” and “Orbital currents in solids (https://orbitalcurrents2023.icmab.es/)”

More information at https://topologicalinterfaces2024.icmab.es/

Emanuele Longo delivers a talk at the CIC nanoGune Institute in Donostia-San Sebastian the 14th March 2024 with title “Ferromagnetic resonance experiments on SrVO3 thin films: Evidence of orbital currents?” hosted by Prof Felix Casanova.

Gervasi Herranz delivers a talk (IN-PERSON MEETING) on 6^th March at 2:18 PM at the APS March Meeting 2024 (Minneapolis, Minnesota, USA) in Session N04: Ordering Phenomena in Spin-Orbit Coupled Systems

Room: L100D The talk is N04.00011 : Electromagnetic detection of spin-orbit entangled states in Jahn-Teller Mn3+ ions”.
Gyanendra Singh delivers a talk (VIRTUAL MEETING) on 6^th March at 12:30 PM the APS March Meeting 2024 (Minneapolis, Minnesota, USA) Abstract: HH05.00006 : Stoichiometric control of 2D superconductivity and mobility at SrTiO3-based interfaces.

The ICMAB organized Orbital Currents School 2023 conclued. 

With a participation of about 70 attendants in-person and 110 on line, the School has finished. A very exciting Introductory lecture by Tatiana G. Rappoport, was followed by lectures by Aurélien Manchon, Dongwook Go, Enric Canadell, Hyun-Woo Lee and Can Onur Avci, which motivated living discussions, comments and suggested intriguing prospectives.