A5031501224- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Theoretical and Computational Physics
- Multiferroics and related materials
- Topological Materials and Phenomena
- Nuclear materials and radiation effects
- Mineralogy and Gemology Studies
- Geological and Geochemical Analysis
- Quasicrystal Structures and Properties
- Organic and Molecular Conductors Research
- Quantum many-body systems
- Perovskite Materials and Applications
- Complex Systems and Time Series Analysis
- X-ray Diffraction in Crystallography
- earthquake and tectonic studies
- Algebraic structures and combinatorial models
- Phase-change materials and chalcogenides
- Plant and Fungal Species Descriptions
- Material Dynamics and Properties
- Quantum, superfluid, helium dynamics
- Iron-based superconductors research
- Molecular spectroscopy and chirality
- Metallic Glasses and Amorphous Alloys
- Crystal Structures and Properties
Laboratoire de physique des Solides
2016-2025
Université Paris-Saclay
2016-2025
Centre National de la Recherche Scientifique
2015-2024
Université Paris-Sud
2013-2024
Université Paris Nanterre
2012
Service de Physique de l'État Condensé
2003-2005
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2004-2005
CEA Paris-Saclay
2004-2005
DSM (Netherlands)
2004
We report muon spin rotation measurements on the S=1/2 (Cu2+) paratacamite ZnxCu4-x(OH)6Cl2 family. Despite a Weiss temperature of approximately -300 K, x=1 compound is found to have no transition magnetic frozen state down 50 mK as theoretically expected for kagomé Heisenberg antiferromagnet. find that limit between dynamical and partly ground occurs around x=0.5. For x=1, we discuss relevance singlet picture.
Magnetic susceptibility, NMR, muon spin relaxation, and inelastic neutron scattering measurements show that kapellasite, Cu3Zn(OH)6Cl2, a geometrically frustrated spin-1/2 kagome antiferromagnet polymorphic with herbertsmithite, is gapless liquid showing unusual dynamic short-range correlations of noncoplanar cuboc2 type which persist down to 20 mK. The Hamiltonian determined from fit high-temperature series expansion bulk susceptibility data possesses competing exchange interactions....
We report, through $^{17}\mathrm{O}$ NMR, an unambiguous local determination of the intrinsic kagome lattice spin susceptibility as well that created around nonmagnetic defects arising from natural $\mathrm{Zn}/\mathrm{Cu}$ exchange in $S=1/2$ (${\mathrm{Cu}}^{2+}$) herbertsmithite ${\mathrm{ZnCu}}_{3}(\mathrm{OH}{)}_{6}{\mathrm{Cl}}_{2}$ compound. The issue a singlet--triplet gap is addressed. magnetic response defect found to markedly differ observed nonfrustrated antiferromagnets....
We report the determination of Dzyaloshinsky-Moriya interaction, dominant magnetic anisotropy term in kagome spin-1/2 compound ${\mathrm{ZnCu}}_{3}(\mathrm{OH}{)}_{6}{\mathrm{Cl}}_{2}$. Based on analysis high-temperature electron spin resonance (ESR) spectra, we find its main component $|{D}_{z}|=15(1)\text{ }\text{ }\mathrm{K}$ to be perpendicular planes. Through temperature dependent ESR linewidth, observe a building up nearest-neighbor spin-spin correlations below...
The vanadium oxyfluoride [NH(4)](2)[C(7)H(14)N][V(7)O(6)F(18)] (DQVOF) is a geometrically frustrated magnetic bilayer material. structure consists of S = 1/2 kagome planes V(4+) d(1) ions with 1 V(3+) d(2) located between the layers. Muon spin relaxation measurements demonstrate absence freezing down to 40 mK despite an energy scale 60 K for antiferromagnetic exchange interactions. From magnetization and heat capacity we conclude that spins interplane are weakly coupled layers, such DQVOF...
After introducing the field of Highly Frustrated Magnetism through quest for a quantum spin liquid in dimension higher than one, we focus on emblematic case kagome network. From theoretical point view, simple Heisenberg an antiferromagnetic lattice decorated with spins has been long-standing problem, not solved yet. Experimental realizations have remained scarce long until discovery herbertsmithite ZnCu3(OH)6Cl2 2005. This is one very few candidates that triggered burst activity both theory...
The dc magnetization of the unique $S=\frac{1}{2}$ kagome antiferromagnet Herbertsmithite has been measured down to $0.1\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. No sign spin freezing is observed in agreement with former $\ensuremath{\mu}\mathit{SR}$ and ac-susceptibility results. low temperature magnetic response dominated by a defect contribution which exhibits an energy scale $\ensuremath{\simeq}1\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, likely reflecting coupling defects. component saturated...
We report magnetization, specific heat, muon spin rotation, and Na NMR measurements on the $S=3/2$ rhombohedrally stacked Heisenberg antiferromagnet ${\mathrm{NaCrO}}_{2}$. This compound appears to be a good candidate for study of isotropic triangular antiferromagnets with very weak interlayer coupling. While heat magnetization indicate onset transition in range ${T}_{c}\ensuremath{\sim}40--50\text{ }\text{ }\mathrm{K}$, both rotation reveal fluctuating crossover regime extending well below...
The frustration of antiferromagnetic interactions on the loosely connected kagome lattice associated to enhancement quantum fluctuations for S=1/2 spins was acknowledged long ago as a keypoint stabilize novel ground states magnetic matter. Only very recently, model compound Herbersmithite, ZnCu3(OH)6Cl2, structurally perfect antiferromagnet, could be synthesized and enables close comparison theories. We review classify various experimental results obtained over past years underline some...
Strong spin-orbit coupling (SOC) effects of heavy $d$-orbital elements have long been neglected in describing the ground states their compounds thereby overlooking a variety fascinating and yet unexplored magnetic electronic states, until recently. The entangled electrons such can get stabilized into unusual multiplet $J$-states which warrants severe investigations. Here we show using detailed thermodynamic studies theoretical calculations state Ba$_3$ZnIr$_2$O$_9$, 6$H$ hexagonal perovskite...
PbCuTe2O6 is a rare example of spin liquid candidate featuring three dimensional magnetic lattice. Strong geometric frustration arises from the dominant antiferromagnetic interaction which generates hyperkagome network Cu2+ ions although additional interactions enhance lattice connectivity. Through combination magnetization measurements and local probe investigation by NMR muSR down to 20 mK, we provide robust evidence for absence freezing in ground state. The susceptibility probed shift...
We report on an extensive study of the influence spin anisotropy glass aging dynamics. New temperature cycle experiments allow us to compare quantitatively memory effect in four Heisenberg glasses with various degrees random and one Ising glass. The sharpness appears decrease continuously anisotropy. Besides, coherence length is determined by magnetic field change for first time sample. For three representative samples, from glasses, we can consistently account both sets (temperature change)...
We report $^{17}\mathrm{O}$ NMR measurements in the $S=1/2\text{ }({\mathrm{Cu}}^{2+})$ kagome antiferromagnet Herbertsmithite ${\mathrm{ZnCu}}_{3}(\mathrm{OH}{)}_{6}{\mathrm{Cl}}_{2}$ down to 45 mK magnetic fields ranging from 2 12 T. While displays a gapless spin-liquid behavior zero field, we uncover an instability toward spin-solid phase at sub-Kelvin temperature induced by applied field. The latter shows largely suppressed moments $\ensuremath{\lesssim}0.1{\ensuremath{\mu}}_{B}$ and...
We report muSR experiments on Mg{x}Cu{4-x}(OH)6Cl2 with x \sim 1, a new material isostructural to Herbertsmithite exhibiting regular kagome planes of spin 1/2 (Cu^{2+}), and therefore candidate for liquid ground state. evidence the absence any magnetic ordering down 20 mK (\sim J/10^4). investigate in detail dynamics well characterized samples zero applied longitudinal fields propose low T defect based interpretation explain unconventional observed quantum phase.
We report an electron spin resonance investigation of the geometrically frustrated spin-1/2 kagome antiferromagnet vesignieite, BaCu$_3$V$_2$O$_8$(OH)$_2$. Analysis line widths and shifts indicates dominance in-plane Dzyaloshinsky-Moriya anisotropy that is proposed to suppress strongly quantum fluctuations thus promote long-range ordering rather than a spin-liquid state. also evidence enhanced spin-phonon contribution might originate from lattice instability discuss origin low-temperature...
We report $^{35}\mathrm{Cl}$ NMR, ESR, $\ensuremath{\mu}\mathrm{SR}$, and specific-heat measurements on the $S=\frac{1}{2}$ frustrated kagome magnet kapellasite $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Cu}}_{3}{\text{Zn(OH)}}_{6}{\mathrm{Cl}}_{2}$, where a gapless spin-liquid phase is stabilized by set of competing exchange interactions. Our confirm ferromagnetic character nearest-neighbor interaction ${J}_{1}$ give an energy scale for interactions $|J|\ensuremath{\sim}10$ K. The...
Employing complementary torque magnetometry and electron spin resonance on single crystals of herbertsmithite, the closest realization to date a quantum kagome antiferromagnet featuring spin-liquid ground state, we provide novel insight into different contributions its magnetism. At low temperatures, two distinct types defects with magnetic couplings spins are found. Surprisingly, their response contradicts threefold symmetry ideal lattice, suggesting presence global structural distortion...
Volborthite compound is one of the very few realizations S=1/2 quantum spins on a highly frustrated kagome-like lattice. Low-T SQUID measurements reveal broad magnetic transition below 2K which further confirmed by peak in 51V nuclear spin relaxation rate (1/T1) at 1.4K$\pm$0.2K. Through NMR, ground state (GS) appears to be mixture different configurations, among 20% correspond well defined short range order, possibly $\sqrt{3} \times \sqrt{3}$ type. While freezing involve all Cu$^{2+}$...
Using muon spin rotation, well-defined bulk ~ 100% magnetic phases in NaxCoO2 are revealed. A novel phase is detected for x = 0.85 with the highest transition temperature ever observed >= 0.75. This stresses diversity of >=0.75 and link between structural degrees freedom. For charge-ordered 0.50 compound, a cascade transitions below 85 K. From detailed analysis our data, we conclude that ordered moment varies continuously suggest two secondary at 48 K 29 correspond to moderate reorientation...
The intrinsic magnetic susceptibility and local magnetization of the near-kagome quantum magnet vesignieite, Cu3BaV2O8(OH)2, are presented as measured using 51V NMR. NMR line shift gives an accurate measurement kagome sites which closely resembles that spin liquid herbertsmithite [A. Olariu et al. Phys. Rev. Lett. 100, 087202 (2008)]. It is therefore surprising that, at Tc ~ 9 K, a transition to heterogeneous ground state observed. A gradual wipeout half intensity indicates slowly...
We present a method to build magnetic models of insulators based on high-temperature expansions by fitting both the susceptibility and low-temperature specific heat data. It is applied frustrated magnet kapellasite [Cu${}_{3}$Zn(OH)${}_{6}$Cl${}_{2}$] with ${J}_{1}\ensuremath{-}{J}_{2}\ensuremath{-}{J}_{d}$-Heisenberg model kagome lattice. Experimental data are reproduced set competing exchange energies centered at...
We present local probe results on the honeycomb lattice antiferromagnet Ba3CuSb2O9. Muon spin relaxation measurements in zero field down to 20 mK show unequivocally that there is a total absence of freezing ground state. Sb NMR allow us track intrinsic susceptibility lattice, which shows maximum at around 55 K and drops low-temperature limit. The spin-lattice rate two characteristic energy scales, including field-dependent crossover exponential behavior, implying gapped magnetic excitations.
${\mathrm{Na}}_{4}{\mathrm{Ir}}_{3}{\mathrm{O}}_{8}$ is a unique case of hyperkagome 3D corner sharing triangular lattice that can be decorated with quantum spins. It has spurred lot theoretical interest as spin liquid candidate. We present comprehensive set NMR data taken on both the $^{23}\mathrm{Na}$ and $^{17}\mathrm{O}$ sites. show disordered magnetic freezing all Ir sites sets in below ${T}_{f}\ensuremath{\sim}7\text{ }\text{ }\mathrm{K}$, well $J=300\text{ drastic slowing down...