ORCID Profile
0000-0002-6704-3422
Current Organisation
CNRS
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: AIP Publishing
Date: 02-2016
DOI: 10.1063/1.4941672
Publisher: Wiley
Date: 06-04-2020
Publisher: Springer Science and Business Media LLC
Date: 16-03-2020
Publisher: American Physical Society (APS)
Date: 09-10-2019
Publisher: AIP Publishing
Date: 13-11-2019
DOI: 10.1063/1.5113530
Abstract: BiFeO3 thin films have attracted considerable attention by virtue of their potential application in low-energy spintronic and magnonic devices. BiFeO3 possesses an intricate magnetic structure, characterized by a spin cycloid with period ∼62 nm that governs the functional magnonic response, and which can be modulated or even destroyed by strain, magnetic and electric fields, or chemical doping. The literature on (110)-oriented BiFeO3 films is not explicit in defining the conditions under which this cycloid persists, as its presence depends on synthesis method and thin-film boundary conditions, especially in the sub-100 nm thickness regime. This report aims to end “trial and error” approaches in determining the conditions under which this cycloid and its associated functional magnonic response exist. We show that in specific crystallographic orientations of epitaxial BiFeO3, an unexplored strain parameter—the distortion in the ab plane of the monoclinic unit cell—significantly influences the spin structure. Combining Mössbauer spectroscopy and low-energy Raman spectroscopy with first-principles-based effective Hamiltonian calculations, we show that both average strain and this distortion destroy the cycloid. For films grown on (110)-oriented SrTiO3 substrates, if the BiFeO3 lattice parameters a and b differ by more than about 1.2%, the cycloid is destabilized, resulting in a pseudocollinear magnetic order ground state. We are thereby able to construct a phase diagram of the spin structure for nanoscale epitaxial BiFeO3 films, which aims to resolve long-standing literature inconsistencies and provide powerful guidelines for the design of future magnonic and spintronic devices.
Publisher: Springer Science and Business Media LLC
Date: 09-2017
DOI: 10.1038/NATURE23656
Abstract: Although ferromagnets have many applications, their large magnetization and the resulting energy cost for switching magnetic moments bring into question their suitability for reliable low-power spintronic devices. Non-collinear antiferromagnetic systems do not suffer from this problem, and often have extra functionalities: non-collinear spin order may break space-inversion symmetry and thus allow electric-field control of magnetism, or may produce emergent spin-orbit effects that enable efficient spin-charge interconversion. To harness these traits for next-generation spintronics, the nanoscale control and imaging capabilities that are now routine for ferromagnets must be developed for antiferromagnetic systems. Here, using a non-invasive, scanning single-spin magnetometer based on a nitrogen-vacancy defect in diamond, we demonstrate real-space visualization of non-collinear antiferromagnetic order in a magnetic thin film at room temperature. We image the spin cycloid of a multiferroic bismuth ferrite (BiFeO
Publisher: Springer Science and Business Media LLC
Date: 29-01-2018
DOI: 10.1038/S41467-018-02907-8
Abstract: In LaAlO 3 /SrTiO 3 heterostructures, a gate tunable superconducting electron gas is confined in a quantum well at the interface between two insulating oxides. Remarkably, the gas coexists with both magnetism and strong Rashba spin–orbit coupling. However, both the origin of superconductivity and the nature of the transition to the normal state over the whole doping range remain elusive. Here we use resonant microwave transport to extract the superfluid stiffness and the superconducting gap energy of the LaAlO 3 /SrTiO 3 interface as a function of carrier density. We show that the superconducting phase diagram of this system is controlled by the competition between electron pairing and phase coherence. The analysis of the superfluid density reveals that only a very small fraction of the electrons condenses into the superconducting state. We propose that this corresponds to the weak filling of high-energy d xz / d yz bands in the quantum well, more apt to host superconductivity.
Publisher: American Physical Society (APS)
Date: 19-03-2019
Publisher: Springer Science and Business Media LLC
Date: 02-04-2020
DOI: 10.1038/S42005-020-0330-6
Abstract: Many transition metal oxides (TMOs) are Mott insulators due to strong Coulomb repulsion between electrons, and exhibit metal-insulator transitions (MITs) whose mechanisms are not always fully understood. Unlike most TMOs, minute doping in CaMnO 3 induces a metallic state without any structural transformations. This material is thus an ideal platform to explore band formation through the MIT. Here, we use angle-resolved photoemission spectroscopy to visualize how electrons delocalize and couple to phonons in CaMnO 3 . We show the development of a Fermi surface where mobile electrons coexist with heavier carriers, strongly coupled polarons. The latter originate from a boost of the electron-phonon interaction (EPI). This finding brings to light the role that the EPI can play in MITs even caused by purely electronic mechanisms. Our discovery of the EPI-induced dichotomy of the charge carriers explains the transport response of Ce-doped CaMnO 3 and suggests strategies to engineer quantum matter from TMOs.
Publisher: Springer Science and Business Media LLC
Date: 05-08-2015
DOI: 10.1038/SREP12751
Abstract: The recent development in the fabrication of artificial oxide heterostructures opens new avenues in the field of quantum materials by enabling the manipulation of the charge, spin and orbital degrees of freedom. In this context, the discovery of two-dimensional electron gases (2-DEGs) at LaAlO 3 /SrTiO 3 interfaces, which exhibit both superconductivity and strong Rashba spin-orbit coupling (SOC), represents a major breakthrough. Here, we report on the realisation of a field-effect LaAlO 3 /SrTiO 3 device, whose physical properties, including superconductivity and SOC, can be tuned over a wide range by a top-gate voltage. We derive a phase diagram, which emphasises a field-effect-induced superconductor-to-insulator quantum phase transition. Magneto-transport measurements show that the Rashba coupling constant increases linearly with the interfacial electric field. Our results pave the way for the realisation of mesoscopic devices, where these two properties can be manipulated on a local scale by means of top-gates.
No related grants have been discovered for Manuel Bibes.