A5001181915- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Lanthanide and Transition Metal Complexes
- Radioactive element chemistry and processing
- Magnetism in coordination complexes
- Organometallic Complex Synthesis and Catalysis
- Multiferroics and related materials
- Crystal Structures and Properties
- Iron-based superconductors research
- Theoretical and Computational Physics
- Topological Materials and Phenomena
- Rare-earth and actinide compounds
- Inorganic Chemistry and Materials
- Metal-Organic Frameworks: Synthesis and Applications
- Quantum and electron transport phenomena
- Ammonia Synthesis and Nitrogen Reduction
- Ferroelectric and Piezoelectric Materials
- Coordination Chemistry and Organometallics
- Magnetic Properties of Alloys
- Perovskite Materials and Applications
- 2D Materials and Applications
École Polytechnique Fédérale de Lausanne
2016-2025
Czech Academy of Sciences, Institute of Physics
2018-2024
Institute of Physics
2008-2023
Charles Humbert 8
2018-2019
Stockholm University
2006-2007
Uniquely in Cu2OSeO3, the Skyrmions, which are topologically protected magnetic spin vortex-like objects, display a magnetoelectric coupling and can be manipulated by externally applied electric (E) fields. Here, we explore E-field to Skyrmion lattice phase, study response using neutron scattering. Giant induced rotations of achieved that span range $\sim$25$^{\circ}$. Supporting calculations show an E-field-induced distortion lies behind rotation. Overall, present new approach control makes...
Small-angle neutron scattering has been employed to study the influence of applied electric (E-)fields on skyrmion lattice in chiral magnetoelectric Cu(2)OSeO(3). Using an experimental geometry with E-field parallel [111] axis, and magnetic field [11(-)0] we demonstrate that effect applying is controllably rotate around axis. Our results are important first demonstration for a microscopic coupling between E-fields skyrmions insulator, show general emergent properties may be tailored...
Lanthanides (Ln) usually occur in the +3, or more recently +2, oxidation states. The only example of an isolated molecular Ln4+ so far remains Ce4+. Here we show that +4 state is also accessible a compound terbium as demonstrated by tetrakis(siloxide)terbium(III) ate complex, [KTb(OSi(OtBu)3)4], 1-Tb, with tris(4-bromophenyl)amminium oxidant, [N(C6H4Br)3][SbCl6], to afford Tb4+ complex [Tb(OSi(OtBu)3)4], 2-Tb. solid structures 1-Tb and 2-Tb were determined X-ray crystallography, presence was...
Abstract Total control over the electronic spin relaxation in molecular nanomagnets is ultimate goal design of new molecules with evermore realizable applications spin-based devices. For single-ion lanthanide systems, strong spin–orbit coupling, potential are linked to energetic structure crystal field levels and quantum tunneling within ground state. Structural engineering timescale these events via appropriate fields represents a fundamental challenge for synthetic chemist, since tunnel...
Out of the 14 lanthanide (Ln) ions, molecular complexes Ln(IV) were known only for cerium and more recently terbium. Here we demonstrate that +IV oxidation state is also accessible large praseodymium (Pr) cation. The tetrakis(triphenysiloxide) Pr(III) ate complex, [KPr(OSiPh3)4(THF)3], 1-PrPh, with [N(C6H4Br)3][SbCl6], affords Pr(IV) complex [Pr(OSiPh3)4(MeCN)2], 2-PrPh, which stable once isolated. solid structure, UV–visible spectroscopy, magnetometry, cyclic voltammetry data along DFT...
The synthesis of molecular uranium complexes in oxidation states lower than +3 remains a challenge despite the interest for their multielectron transfer reactivity and electronic structures. Herein, we report one- two-electron reduction U(III) complex supported by an arene-tethered tris(siloxide) tripodal ligand leading to mono-reduced complexes, [K(THF)U((OSi(OtBu)2Ar)3-arene)(THF)] (2) [K(2.2.2-cryptand)][U((OSi(OtBu)2Ar)3-arene)(THF)] (2-crypt), di-reduced U(I) synthons,...
Herein, we report the redox reactivity of a multimetallic uranium complex supported by triphenylsiloxide (-OSiPh3 ) ligands, where show that low valent synthons can be stabilized via an unprecedented mechanism involving intramolecular ligand migration. The two- and three-electron reduction oxo-bridged diuranium(IV) [{(Ph3 SiO)3 (DME)U}2 (μ-O)], 4, yields formal "UII /UIV ", 5, "UI 6, complexes migration formation uranium-arene δ-bond interactions. Remarkably, 5 effects two-electron reductive...
Robust arene-anchored polydentate siloxide ligands allow to control unwanted ligand rearrangements for the isolation of Tb( iv ) complexes thus enabling use iii )/Tb( couple separation Tb from neighboring Dy ion.
Abstract The synthesis of lanthanides other than cerium in the oxidation state +IV has remained a desirable but unmet target until recently, when two examples Tb IV with saturated coordination spheres were isolated. Here we report third example an isolated molecular complex terbium(IV), where supporting siloxide ligands do not saturate sphere. fully characterized six‐coordinate [Tb (OSiPh 3 ) 4 (MeCN) 2 ], ‐Tb Ph , shows high stability and labile MeCN can be replaced by phosphinoxide...
Exotic quantum phases, arising from a complex interplay of charge, spin, lattice and orbital degrees freedom, are immense interest to wide research community. A well-known example such an entangled behavior is the Jahn-Teller effect, where lifting degeneracy proceeds through distortions. Here we demonstrate that highly-symmetrical 5d1 double perovskite Ba2MgReO6, comprising 3D array isolated ReO6 octahedra, represents rare dynamic system in strong spin-orbit coupling regime. Thermodynamic...
Quantum spin liquids (QSLs) have become a key area of research in magnetism due to their remarkable properties, such as long-range entanglement, fractional excitations, and topologically protected phenomena. Recently, the search for QSLs has expanded into three-dimensional world, despite suppression quantum fluctuations high dimensionality. A new candidate material, K2Ni2(SO4)3, belongs langbeinite family consists two interconnected trillium lattices. Although magnetically ordered, it...
We present a detailed ac susceptibility investigation of the fluctuation regime in insulating cubic helimagnet ${\text{Cu}}_{2}$${\text{OSeO}}_{3}$. For magnetic fields ${\ensuremath{\mu}}_{0}H\ensuremath{\ge}200$ mT, and over wide temperature ($T$) range, system behaves according to scaling relations characteristic classical three-dimensional Heisenberg model. lower fields, is preserved only at higher $T$ becomes renormalized narrow-$T$ range above transition temperature. Contrary...
The synthesis and characterization of a new class neutral aminyl radicals is reported. Monoradicals were obtained by reduction azoimidazolium dyes with potassium. Structural, spectroscopic, computational data suggest that the spin density centered on one nitrogen atoms former azo group. dimeric dye an octamethylbiphenylene bridge between groups resulted in formation biradical largely independent unpaired electrons. Both monoradicals found to display high stability solution as well solid state.
Synthetic studies of bimetallic uranium nitride complexes with the N(SiMe3)2 ligand have generated a new complex U(III), which is highly reactive toward C–H bonds and H2. Treatment previously reported U(IV)/U(IV) [Na(DME)3][((Me3Si)2N)2U(μ-N)(μ-κ2:CN̵–CH2SiMe2NSiMe3)U(N(SiMe3)2)2] (DME = 1,2-dimethoxyethane), 1, 2 equiv HNEt3BPh3 yielded cationic complex, [{((Me3Si)2N)2U(THF)}2(μ-N)][BPh4] (THF tetrahydrofuran), 3, by successive protonolysis one uranium–methylene bond. Reduction 3 KC8...
A combined density functional theory and resonant elastic x-ray scattering technique is implemented to demonstrate the role of charge multipole correlation order in a 5$d$${}^{1}$ double perovskite compound that driven by complex coupled spin, charge, multipole, structural order.
We report a comprehensive study of magnetic properties Ni3TeO6. The system crystallizes in noncentrosymmetric rhombohedral lattice, space group R3. There are three differently coordinated Ni atoms the unit cell. Two them form an almost planar honeycomb while third one is placed between layers. Magnetization and specific heat measurements revealed single ordering at TN = 52 K. Below susceptibility with field parallel to c axis drops towards zero perpendicular remains constant, characteristic...
The recent discovery of magnetic skyrmion lattices initiated a surge interest in the scientific community. Several novel phenomena have been shown to emerge from interaction conducting electrons with lattice, such as topological Hall-effect and spin-transfer torque at ultra-low current densities. In insulating compound Cu2OSeO3, magneto-electric coupling enables control lattice via electric fields, promising dissipation-less route towards spintronic devices. One outstanding fundamental...
Abstract Magnetic skyrmions are topologically protected spin-whirls currently considered as promising for use in ultra-dense memory devices. Towards achieving this goal, exploration of the skyrmion phase response and under external stimuli is urgently required. Here we show experimentally, explain theoretically, that magnetoelectric insulator Cu 2 OSeO 3 can expand shrink significantly depending on polarity a moderate applied electric field (few V/ μ m). The theory develop incorporates...
A diuranium(<sc>v</sc>) bis-nitride complex supported by siloxide ligands displays remarkable reactivity in ambient conditions with small molecules such as CS<sub>2</sub>, CO<sub>2</sub>, CO and H<sub>2</sub> resulting N–C N–H bond formation. The nitride linker also leads to an unusually strong antiferromagnetic coupling between uranium(<sc>v</sc>) ions.
Quantum spin liquids are exotic states of matter that form when strongly frustrated magnetic interactions induce a highly entangled quantum paramagnet far below the energy scale interactions. Three-dimensional cases especially challenging due to significant reduction influence fluctuations. Here, we report characterization K_{2}Ni_{2}(SO_{4})_{3} forming three-dimensional network Ni^{2+} spins. Using density functional theory calculations, show this consists two interconnected spin-1...
Multimetallic cooperativity is believed to play a key role in the cleavage of dinitrogen nitrides (N3–), but mechanism remains ambiguous due lack isolated intermediates. Herein, we report reduction complex [K2{[UV(OSi(OtBu)3)3]2(μ-O)(μ-η2:η2-N2)}], B, with KC8, yielding tetranuclear tetranitride cluster [K6{(OSi(OtBu)3)2UIV}3{(OSi(OtBu)3)2UVI}(μ4-N)3(μ3-N)(μ3-O)2], 1, novel example N2 nitride by diuranium complex. The structure 1 remarkable, as it contains unique uranium center bound four...