Low-Frequency Imaginary Impedance at the Superconducting Transition of 2 H - Nb Se 2

Isoreticular two-dimensional magnetic coordination polymers prepared through pre-synthetic ligand functionalization

Chemical functionalization is a powerful approach to tailor the physical and chemical properties of two-dimensional (2D) materials, increase their processability and stability, tune their functionalities and, even, create new 2D materials. This is typically achieved through post-synthetic functionalization by anchoring molecules on the surface of an exfoliated 2D crystal, but it inevitably alters the long-range structural order of the material. Here we present a pre-synthetic approach that allows the isolation of crystalline, robust and magnetic functionalized monolayers of coordination polymers. A series of five isostructural layered magnetic coordination polymers based on Fe(ii) centres a…

Force-free state in a superconducting single crystal and angle-dependent vortex helical instability

Superconducting 2H-NbSe2 single crystals show intrinsic low pinning values. Therefore, they are ideal materials with which to explore fundamental properties of vortices. (V, I) characteristics are the experimental data we have used to investigate the dissipation mechanisms in a rectangular shape 2H-NbSe2 single crystal. Particularly, we have studied dissipation behavior with magnetic fields applied in the plane of the crystal and parallel to the injected currents, i.e. in the force-free state where the vortex helical instability governs the vortex dynamics. In this regime, the data follow the elliptic critical state model and the voltage dissipation shows an exponential dependence.Moreover,…

Path to Overcome Material and Fundamental Obstacles in Spin Valves Based on Mo S 2 and Other Transition-Metal Dichalcogenides

International audience; Experimental studies on spin valves with exfoliated 2D materials face the main technological issue of ferromagnetic electrode oxidation during the 2Ds integration process. As a twofold outcome, magne-toresistance (MR) signals are very difficult to obtain and, when they finally are, they are often far from expectations. We propose a fabrication method to circumvent this key issue for 2D-based spintronics devices. We report on the fabrication of NiFe/MoS 2 /Co spin valves with mechanically exfoliated mul-tilayer MoS 2 using an in situ fabrication protocol that allows high-quality nonoxidized interfaces to be maintained between the ferromagnetic electrodes and the 2D la…

A quantum spin liquid candidate isolated in a two-dimensional CoIIRhIII bimetallic oxalate network

A quantum spin liquid (QSL) is an elusive state of matter characterized by the absence of long-range magnetic order, even at zero temperature, and by the presence of exotic quasiparticle excitations. In spite of their relevance for quantum communication, topological quantum computation and the understanding of strongly correlated systems, like high-temperature superconductors, the unequivocal experimental identification of materials behaving as QSLs remains challenging. Here, we present a novel 2D heterometallic oxalate complex formed by high-spin Co(II) ions alternating with diamagnetic Rh(III) in a honeycomb lattice. This complex meets the key requirements to become a QSL: a spin ½ ground…

Transient attosecond soft-X-ray spectroscopy in layered semi-metals (Conference Presentation)

X-ray absorption fine-structure (XAFS) spectroscopy is a well-established technique capable of extracting information about a material’s electronic and lattice structure with atomic resolution. While the near-edge region (XANES) of a XAFS spectrum provides information about the electronic configuration, structural information is extracted from the extended XAFS (EXAFS) spectrum, consisting of several hundreds of eV above the absorption edge. With the advent of high harmonic sources, reaching photon energies in soft x-ray (SXR) region, it now becomes possible to connect the spectroscopic capabilities of XAFS to the unprecedented attosecond temporal resolution of a high harmonic source allowi…

Field dependence of the vortex core size probed by scanning tunneling microscopy

We study the spatial distribution of the density of states (DOS) at zero bias N(r) in the mixed state of single and multigap superconductors. We provide an analytic expression for N(r) based on deGennes' relationship between DOS and the order parameter that reproduces well scanning tunneling microscopy (STM) data in several superconducting materials. In the single gap superconductor β-Bi2Pd, we find that N(r) is governed by a length scale ξH=φ0/2πH, which decreases in rising fields. The vortex core size C, defined via the slope of the order parameter at the vortex center, C (dΔ/dr|r→0)-1, differs from ξH by a material dependent numerical factor. The new data on the tunneling conductance and…

Pressure-Induced Collapse of the Charge Density Wave and Higgs Mode Visibility in 2H−TaS2

International audience; The pressure evolution of the Raman active electronic excitations of the transition metal dichalcogenides 2H−TaS2 is followed through the pressure phase diagram embedding incommensurate charge-density-wave and superconducting states. At high pressure, the charge-density wave is found to collapse at 8.5 GPa. In the coexisting charge-density-wave and superconducting orders, we unravel a strong in-gap superconducting mode, attributed to a Higgs mode, coexisting with the expected incoherent Cooper-pair breaking signature. The latter remains in the pure superconducting state reached above 8.5 GPa. Our report constitutes a new observation of such Raman active Higgs mode si…

Attosecond Soft-X-Ray Spectroscopy in a Transition Metal Dichalcogenide

Information about the real-time response of carriers to optical fields is paramount to advance information processing or to understand the bottlenecks of light-matter interaction and energy harvesting. Transition-metal dichalcogenide (TMDC) compounds are an emerging class of materials with attractive structural and electronic properties that can be thinned to the 2D limit and TiS 2 is a paradigmatic example for a semi-metallic TMDC, since its electron mobility ranges between that of a metal and a semiconductor.

Pressure-Induced Collapse of the Charge Density Wave and Higgs Mode Visibility in 2 H − TaS 2

Magnetic order in 2D antiferromagnets revealed by spontaneous anisotropic magnetostriction

The temperature dependent order parameter provides important information on the nature of magnetism. Using traditional methods to study this parameter in two-dimensional (2D) magnets remains difficult, however, particularly for insulating antiferromagnetic (AF) compounds. Here, we show that its temperature dependence in AF MPS$_{3}$ (M(II) = Fe, Co, Ni) can be probed via the anisotropy in the resonance frequency of rectangular membranes, mediated by a combination of anisotropic magnetostriction and spontaneous staggered magnetization. Density functional calculations followed by a derived orbital-resolved magnetic exchange analysis confirm and unravel the microscopic origin of this magnetiza…

Defect-Free Chemical Functionalization of Magnetic Monolayers Based on Coordination Polymers

<p>Chemical functionalization has demonstrated to be a powerful approach to tailor the physical and chemical properties of two-dimensional (2D) materials, to increase their processability and</p> <p>stability, to add new functionalities and, even, to create new 2D materials. However, this post synthetic method – which involves the anchoring of molecules on the surface of an exfoliated 2D crystal – inevitably leads to defective materials, which lack long-range structural order. If defect-free functionalized monolayers are required, a radically new approach needs to be developed. Here we present a pre-synthetic method based on coordination chemistry that affords the isolatio…

Controlling magnetism with light in zero orbital angular momentum antiferromagnet

Antiferromagnetic materials feature intrinsic ultrafast spin dynamics, making them ideal candidates for future magnonic devices operating at THz frequencies. A major focus of current research is the investigation of optical methods for the efficient generation of coherent magnons in antiferromagnetic insulators. In magnetic lattices endowed with orbital angular momentum, spin-orbit coupling enables spin dynamics through the resonant excitation of low-energy electric dipoles such as phonons and orbital resonances which interact with spins. However, in magnetic systems with zero orbital angular momentum, microscopic pathways for the resonant and low-energy optical excitation of coherent spin …

CCDC 1557895: Experimental Crystal Structure Determination

Related Article: Luka Ðorđević, Cataldo Valentini, Nicola Demitri, Cécile Mézière, Magali Allain, Marc Sallé, Andrea Folli, Damien Murphy, Samuel Mañas-Valero, Eugenio Coronado, Davide Bonifazi|2020|Angew.Chem.,Int.Ed.|59|4106|doi:10.1002/anie.201914025

CCDC 1920493: Experimental Crystal Structure Determination

Related Article: Luka Ðorđević, Cataldo Valentini, Nicola Demitri, Cécile Mézière, Magali Allain, Marc Sallé, Andrea Folli, Damien Murphy, Samuel Mañas-Valero, Eugenio Coronado, Davide Bonifazi|2020|Angew.Chem.,Int.Ed.|59|4106|doi:10.1002/anie.201914025

CCDC 1934948: Experimental Crystal Structure Determination

Related Article: Javier Castells-Gil, Samuel Mañas-Valero, Iñigo J. Vitórica-Yrezábal, Duarte Ananias, João Rocha, Raul Santiago, Stefan T. Bromley, José J. Baldoví, Eugenio Coronado, Manuel Souto, Guillermo Mínguez Espallargas|2019|Chem.-Eur.J.|25|12636|doi:10.1002/chem.201902855

CCDC 1582351: Experimental Crystal Structure Determination

Related Article: Javier López-Cabrelles, Samuel Mañas-Valero, Iñigo J. Vitórica-Yrezábal, Pablo J. Bereciartua, Eugenio Coronado, Guillermo Mínguez Espallargas|2022|Dalton Trans.|51|1861|doi:10.1039/D1DT03734J

CCDC 1054373: Experimental Crystal Structure Determination

Related Article: Alexandre Abhervé, Samuel Mañas-Valero, Miguel Clemente-León, Eugenio Coronado|2015|Chemical Science|6|4665|doi:10.1039/C5SC00957J

CCDC 1934950: Experimental Crystal Structure Determination

Related Article: Javier Castells-Gil, Samuel Mañas-Valero, Iñigo J. Vitórica-Yrezábal, Duarte Ananias, João Rocha, Raul Santiago, Stefan T. Bromley, José J. Baldoví, Eugenio Coronado, Manuel Souto, Guillermo Mínguez Espallargas|2019|Chem.-Eur.J.|25|12636|doi:10.1002/chem.201902855

CCDC 1054374: Experimental Crystal Structure Determination

Related Article: Alexandre Abhervé, Samuel Mañas-Valero, Miguel Clemente-León, Eugenio Coronado|2015|Chemical Science|6|4665|doi:10.1039/C5SC00957J

CCDC 1557896: Experimental Crystal Structure Determination

Related Article: Luka Ðorđević, Cataldo Valentini, Nicola Demitri, Cécile Mézière, Magali Allain, Marc Sallé, Andrea Folli, Damien Murphy, Samuel Mañas-Valero, Eugenio Coronado, Davide Bonifazi|2020|Angew.Chem.,Int.Ed.|59|4106|doi:10.1002/anie.201914025

CCDC 1934947: Experimental Crystal Structure Determination

Related Article: Javier Castells-Gil, Samuel Mañas-Valero, Iñigo J. Vitórica-Yrezábal, Duarte Ananias, João Rocha, Raul Santiago, Stefan T. Bromley, José J. Baldoví, Eugenio Coronado, Manuel Souto, Guillermo Mínguez Espallargas|2019|Chem.-Eur.J.|25|12636|doi:10.1002/chem.201902855

CCDC 1934945: Experimental Crystal Structure Determination

Related Article: Javier Castells-Gil, Samuel Mañas-Valero, Iñigo J. Vitórica-Yrezábal, Duarte Ananias, João Rocha, Raul Santiago, Stefan T. Bromley, José J. Baldoví, Eugenio Coronado, Manuel Souto, Guillermo Mínguez Espallargas|2019|Chem.-Eur.J.|25|12636|doi:10.1002/chem.201902855

CCDC 1934949: Experimental Crystal Structure Determination

Related Article: Javier Castells-Gil, Samuel Mañas-Valero, Iñigo J. Vitórica-Yrezábal, Duarte Ananias, João Rocha, Raul Santiago, Stefan T. Bromley, José J. Baldoví, Eugenio Coronado, Manuel Souto, Guillermo Mínguez Espallargas|2019|Chem.-Eur.J.|25|12636|doi:10.1002/chem.201902855

CCDC 1934946: Experimental Crystal Structure Determination

Related Article: Javier Castells-Gil, Samuel Mañas-Valero, Iñigo J. Vitórica-Yrezábal, Duarte Ananias, João Rocha, Raul Santiago, Stefan T. Bromley, José J. Baldoví, Eugenio Coronado, Manuel Souto, Guillermo Mínguez Espallargas|2019|Chem.-Eur.J.|25|12636|doi:10.1002/chem.201902855

CCDC 1054372: Experimental Crystal Structure Determination

Related Article: Alexandre Abhervé, Samuel Mañas-Valero, Miguel Clemente-León, Eugenio Coronado|2015|Chemical Science|6|4665|doi:10.1039/C5SC00957J

CCDC 1912053: Experimental Crystal Structure Determination

Related Article: Luka Ðorđević, Cataldo Valentini, Nicola Demitri, Cécile Mézière, Magali Allain, Marc Sallé, Andrea Folli, Damien Murphy, Samuel Mañas-Valero, Eugenio Coronado, Davide Bonifazi|2020|Angew.Chem.,Int.Ed.|59|4106|doi:10.1002/anie.201914025

CCDC 1936956: Experimental Crystal Structure Determination

Related Article: Luka Ðorđević, Cataldo Valentini, Nicola Demitri, Cécile Mézière, Magali Allain, Marc Sallé, Andrea Folli, Damien Murphy, Samuel Mañas-Valero, Eugenio Coronado, Davide Bonifazi|2020|Angew.Chem.,Int.Ed.|59|4106|doi:10.1002/anie.201914025

CCDC 1557894: Experimental Crystal Structure Determination

Related Article: Luka Ðorđević, Cataldo Valentini, Nicola Demitri, Cécile Mézière, Magali Allain, Marc Sallé, Andrea Folli, Damien Murphy, Samuel Mañas-Valero, Eugenio Coronado, Davide Bonifazi|2020|Angew.Chem.,Int.Ed.|59|4106|doi:10.1002/anie.201914025

Multistep spin switching in orthogonally-twisted ferromagnetic monolayers

The advent of twisting-engineering in two-dimensional (2D) crystals enables the design of van der Waals (vdW) heterostructures exhibiting emergent properties. In the case of magnets, this approach can afford artificial magnets with tailored spin arrangements that do not exist in nature. Here, we fabricate an artificial magnet by twisting 90 degrees two CrSBr ferromagnetic monolayers with an easy-axis in-plane anisotropy, thus forming an "orthogonally-twisted bilayer". The magneto-transport properties reveal multistep spin switching with a magnetic hysteresis opening, which is absent in the pristine case. By tuning the magnetic field, we modulate the remanent state and coercivity and select …