A5084822588- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Magnetism in coordination complexes
- Multiferroics and related materials
- Theoretical and Computational Physics
- Advanced NMR Techniques and Applications
- X-ray Diffraction in Crystallography
- Crystal Structures and Properties
- Magnetic properties of thin films
- Lanthanide and Transition Metal Complexes
- Crystallization and Solubility Studies
- Organic and Molecular Conductors Research
- Inorganic Chemistry and Materials
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- Quantum many-body systems
- Iron-based superconductors research
- Advancements in Battery Materials
- Polyoxometalates: Synthesis and Applications
- Crystallography and molecular interactions
- Metal complexes synthesis and properties
- Porphyrin and Phthalocyanine Chemistry
- Quantum, superfluid, helium dynamics
- Metal-Organic Frameworks: Synthesis and Applications
Paul Scherrer Institute
2009-2024
École Polytechnique Fédérale de Lausanne
2012-2021
University of Freiburg
2016-2020
Tohoku University
2018
École Nationale Supérieure de Chimie de Montpellier
2018
Université de Montpellier
2018
Centre National de la Recherche Scientifique
2018
Institut Charles Gerhardt Montpellier
2018
ETH Zurich
2009-2017
Charles Humbert 8
2015
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...
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...
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...
BiCu(2)PO(6) is a frustrated two-leg spin-ladder compound with spin gap that can be closed magnetic field of approximately 20 T. This quantum phase transition and its related diagram as function temperature (H, T) are investigated up to 60 T by means specific heat, magnetocaloric effect, magnetization, magnetostriction measurements. In contrast other gapped magnets, undergoes series unexpected first- second-order transitions when an external applied along the crystallographic c axis. The...
NMR measurements of the (29)Si spin-lattice relaxation time T(1) were used to probe spin-1/2 random Heisenberg chain compound BaCu(2)(Si(1-x)Ge(x))(2)O(7). Remarkable differences between pure (x=0) and fully (x=0.5) cases are observed, indicating that randomness generates a distribution local magnetic relaxations. This distribution, which is reflected in stretched exponential relaxation, exhibits progressive broadening with decreasing temperature, caused by growing inequivalence sites....
Using SQUID magnetometry techniques, we have studied the change in magnetization versus applied ac electric field, i.e. magnetoelectric (ME) susceptibility dM/dE, chiral-lattice ME insulator Cu2OSeO3. Measurements of dM/dE response provide a sensitive and efficient probe magnetic phase diagram, observe clearly distinct responses for different phases, including skyrmion lattice phase. By combining our results with theoretical calculation, estimate quantitatively coupling strength as {\lambda}...
The strength of the electron-phonon coupling parameter and its evolution throughout a solid's phase diagram often determines phenomena such as superconductivity, charge- spin-density waves. Its experimental determination relies on ability to distinguish thermally activated phonons from those emitted by conduction band electrons, which can be achieved in an elegant way ultrafast techniques. Separating electronic out-of-equilibrium lattice subsystems, we probed their re-equilibration...
Small-angle diffraction of polarized neutrons and resonant contribution to synchrotron radiation have been applied prove chirality the crystal magnetic structures magnetoelectric insulator ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$. Similarly other chiral magnets with $P{2}_{1}3$ structure corresponding chiralities are linked each via phenomenological Dzyaloshinskii-Moriya interaction. The for ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$ same as is observed MnSi, Mn${}_{1\ensuremath{-}x}$Fe${}_{x}$Si,...
Single-molecule magnets (SMMs) based on lanthanide ions display the largest known blocking temperatures and are best candidates for molecular magnetic devices. Understanding their physical properties is a paramount task further development of field. In particular, poly-nuclear variety SMMs, proper understanding exchange interaction crucial. We discuss strengths weaknesses neutron scattering technique in study these materials particularly determination exchange. illustrate points by...
The magnetism of a quasi-one-dimensional ferromagnetic (FM) compound, K${}_{2}$Cr${}_{8}$O${}_{16}$, has been investigated by muon-spin rotation and relaxation (${\ensuremath{\mu}}^{+}$SR) using powder sample in the temperature range between 2 225 K. Below ${T}_{\mathrm{c}}=163\phantom{\rule{0.28em}{0ex}}$K, precession signals were clearly observed zero-field spectrum, indicating formation static FM order. It was also found that internal field does not change drastically at...
${\text{LiCu}}_{3}{\mathrm{O}}_{3}$ is an antiferromagnetic mixed valence cuprate where trilayers of edge-sharing Cu(II)O ($3{d}^{9}$) are sandwiched in between planes Cu(I) ($3{d}^{10}$) ions, with Li stochastically substituting Cu(II). Angle-resolved photoemission spectroscopy (ARPES) and density functional theory reveal two insulating electronic subsystems that segregated spite sharing common oxygen atoms: a Cu ${d}_{{z}^{2}}/\mathrm{O}$ ${p}_{z}$ derived band (VB) dispersing on the...
We present the investigation of a monoclinic compound SeCuO${}_{3}$ using x-ray powder diffraction, magnetization, torque, and electron-spin-resonance. Structurally based analysis suggests that can be considered as three-dimensional network tetramers. The values intratetramer exchange interactions are extracted from temperature dependence susceptibility amount to $\ensuremath{\sim}\phantom{\rule{-0.16em}{0ex}}200$ K. intertetramer coupling leads development long-range antiferromagnetic order...
The spin-web compound Cu3TeO6, belongs to an intriguing group of materials where magnetism is governed by 3d9 copper Cu2+ ions. This has been sparsely experimentally studied and we here present the first investigation its local magnetic properties using muon-spin relaxation/rotation ({\mu}+SR). Our results show a clear long-range 3D order below TN as indicated zero-field (ZF) muon-precessions. At = 61.7 K very sharp transition observed in weak transverse-field (wTF) well ZF data. Contrary...
A 1D, end-on azido- and phenoxo-bridged, coordination polymer, [Cu<sub>2</sub>(μ-NAPPR)(μ<sub>1,1</sub>-N<sub>3</sub>)<sub>2</sub>]<sub>n</sub> (<bold>1</bold>), (NAPPR<sup>2−</sup> = 1,3-bis(naphthylideneimino)propane dianion), was synthesized characterized.
The magnetic properties of the olivine-type compounds LiMPO4 (M = Mn, Co, Ni) are probed using muon spin rotation/relaxation (μSR). These materials pose an appealing structure and a high -potential technological interest as cathode for future rechargeable Li-ion batteries. family consists corner-sharing MO6 octahedra high-spin M2+ ions manifesting antiferromagnetic ground state below TN ≈ 30 K. Additionally, these belong to class exhibiting between two-and three dimensional systems. A...
The disordered quasi-one-dimensional magnet BaCu${}_{2}$SiGeO${}_{7}$ is considered as one of the best physical realizations random Heisenberg chain model, which features an irregular distribution exchange parameters and whose ground state predicted to be scarcely investigated random-singlet (RSS). Based on extensive ${}^{29}$Si NMR magnetization studies BaCu${}_{2}$SiGeO${}_{7}$, combined with numerical quantum Monte Carlo simulations, we obtain remarkable quantitative agreement theoretical...
The low-temperature microscopic magnetic properties of the quasi-2D heavy- fermion compound, CePt2In7 are investigated by using a positive muon-spin rotation and relaxation (μ+SR) technique. Clear evidence for formation commensurate antiferromagnetic order below TN ≈ 5.40 K is presented. parameter shown to fit well modified BCS gap-energy function in strong-coupling scenario.
The novel iridate Ba8Al2IrO14 was prepared as single crystals by self-flux method, thereby providing a rare example of an all-Ir(VI) compound that can be synthesized under ambient pressure conditions. preparation all-Ir(6+) without using traditional high-pressure techniques has to our knowledge previously only been reported in Nd2K2IrO7 and Sm2K2IrO7. monoclinic crystal structure (space group C2/m, No.12) is stable down 90 K contains layers IrO6 octahedra separated Ba AlO4 tetrahedra....
An inelastic neutron scattering study of Cu2Te2O5X2 (X=Cl, Br) shows strong dispersive modes with large energy gaps persisting far above TN, notably in Cu2Te2O5Br2. The anomalous features: a coexisting unusually weak Goldstone-like mode observed Cu2Te2O5Cl2 and the size cannot be explained by existing theories, such as our mean-field or random-phase approximation. We argue that findings represent new general type behavior due to intercluster quantum fluctuations call for development...
The magnetism of a metallic two-dimensional triangular antiferromagnetic (AF) compound, Ag${}_{2}$CrO${}_{2}$, has been investigated by muon-spin rotation and relaxation (${\ensuremath{\mu}}^{+}$SR) using powder sample in the temperature range between 1.8 40 K. Below ${T}_{\mathrm{N}}=24$ K, precession signal was clearly observed zero-field spectrum, indicating formation static AF order. It also found that internal field is independent except for vicinity ${T}_{\mathrm{N}}$, as case...
We present a versatile high voltage sample stick that fits into all cryomagnets and standard cryostats at the Swiss Spallation Neutron Source, Paul Scherrer Institut, which provides low effort route to neutron scattering experiments combine electric field with temperature magnetic field. The allows for voltages up 5 kV can be easily adapted different geometries. discuss design consideration thermal behavior of stick, give one example showcase abilities device.
We have studied low-temperature magnetic properties as well high-temperature lithium ion diffusion in the battery cathode materials LixNi1/3Co1/3Mn1/3O2 by use of muon spin rotation/relaxation. Our data reveal that samples enter into a 2D spin-glass state below TSG ≈ 12 K. further show channels become active for T ≥ Tdiff ~ 125 K where Li-ion hopping-rate [v(T)] starts to increase exponentially. Further, v(T) is found fit very an Arrhenius type equation and activation energy process...
A pentanuclear CuII5-hydroxo cluster possessing an unusual linear-shaped configuration was formed and crystallized under hydrothermal conditions as a result of the unique cooperation bridging 1,2,4-triazole ligand ( trans-1,4-cyclohexanediyl-4,4'-bi(1,2,4-triazole) tr2 cy)), MoVI-oxide, CuSO4. This structural motif can be rationalized by assuming in situ generation {Cu2Mo6O22}4- anions, which represent heteroleptic derivatives γ-type [Mo8O26]4- further interlinked [Cu3(OH)2]4+ cations...
The title compound belongs to a wide group of quasi-one-dimensional (Q1D) antiferromagnets (AF) and its Co2+ ions form Q1D screw-chains along the c-axis. We here present first investigation microscopic magnetic nature single crystalline BaCo2V2O8 sample using {\mu}+SR. Our data reveal presence several clear muon frequencies below TN indicating onset long-range order. Above 5 K, {\mu}+SR spectra is well fitted simple power-exponential relaxing function. temperature dependence relaxation-rate...