A5107960777- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Theoretical and Computational Physics
- Magnetism in coordination complexes
- 2D Materials and Applications
- Organic and Molecular Conductors Research
- Magnetic properties of thin films
- Multiferroics and related materials
- Magnetic and transport properties of perovskites and related materials
- ZnO doping and properties
- Perovskite Materials and Applications
École Polytechnique Fédérale de Lausanne
2012-2023
Paul Scherrer Institute
2008-2013
ETH Zurich
2008-2010
Vifor Pharma (Switzerland)
2008
Centre National de la Recherche Scientifique
2008
Institut Néel
2008
National Interuniversity Consortium of Materials Science and Technology
2008
We present an experimental study of the two-dimensional $S=\frac{1}{2}$ square-lattice antiferromagnet $\text{Cu}{(\text{pz})}_{2}{({\text{ClO}}_{4})}_{2}$ (pz denotes pyrazine-${\text{C}}_{4}{\text{H}}_{4}{\text{N}}_{2}$) using specific-heat measurements, neutron diffraction, and cold-neutron spectroscopy. The magnetic field dependence ordering temperature was determined from measurements for fields perpendicular parallel to planes, showing identical field-temperature phase diagrams. This...
We have studied the two-dimensional S=1/2 square-lattice antiferromagnet Cu(pz)_{2}(ClO4)_{2} (where pz denotes pyrazine), using neutron inelastic scattering and series expansion calculations. show that presence of antiferromagnetic next-nearest-neighbor interactions enhances quantum fluctuations associated with resonating valence bonds. Intermediate magnetic fields lead to a selective tuning bonds spectacular inversion zone-boundary dispersion, providing novel insight into 2D...
High-temperature superconductivity remains arguably the largest outstanding enigma of condensed matter physics. The discovery iron-based high-temperature superconductors has renewed importance understanding in materials susceptible to magnetic order and fluctuations. Intriguingly they show fluctuations reminiscent superconducting (SC) cuprates, including a 'resonance' an 'hour-glass' shaped dispersion, which provide opportunity new insight coupling between spin superconductivity. Here we...
We study the strongly anisotropic quasi-one-dimensional S = 1 quantum magnet NiCl2⋅4SC(NH2)2 using elastic and inelastic neutron scattering. demonstrate that a magnetic field splits excited doublet state drives lower to zero energy at critical Hc1. For Hc1 < H Hc2, where Hc2 indicates transition fully magnetized state, three-dimensional order is established with AF moment perpendicular field. mapped temperature/magnetic phase diagram, we find total ordered reaches mtot 2.1 μB μ0H 6 T thus...
The spin-gap evolution upon Ca doping in Sr${}_{14\ensuremath{-}x}$Ca${}_{x}$Cu${}_{24}$O${}_{41}$ was systematically investigated using inelastic neutron scattering. We discover that the singlet-triplet excitation survives this series with $x$ up to 13, indicating singlet dimer ground state these compounds. This observation corrects previous speculation spin gap collapses at \ensuremath{\sim} 13 by NMR technique. strong intensity modulation along ${Q}_{\mathrm{H}}$ $x=0$ gradually evolves...
Transition-metal dichalcogenides (TMDs) are layered compounds that support many electronic phases, including various charge density waves, superconducting, and Mott insulating states. Their intercalation with magnetic ions introduces sublayers, which strongly influence the coupling between host layers, feature states adjustable by external means. ${\mathrm{Co}}_{1/3}\mathrm{Nb}{\mathrm{S}}_{2}$ hosts a particularly sensitive subsystem lowest ordering temperature in family of magnetically...
We present the experimental phase diagram of LiHo$_x$Er$_{1-x}$F$_4$, a dilution series dipolar-coupled model magnets.The was determined using combination AC susceptibility and neutron scattering. Three unique phases in addition to Ising ferromagnet LiHoF$_4$ XY anti-ferromagnet LiErF$_4$ have been identified. Below $x=0.86$ an embedded spin-glass is observed, where exists within ferromagnetic structure. $x=0.57$ observed consisting frozen needle-like clusters. For $x \sim 0.3 - 0.1$...
Iron based high temperature superconductors have several common features with superconducting cuprates, including the square lattice and proximity to an antiferromagnetic phase. The magnetic excitation spectrum below Tc of shows hourglass-shaped dispersion a resonance around commensurate point . In previous inelastic neutron scattering study, we showed that is most likely prerequisite for superconductivity, while consequences are opening gap shift spectral weight. this paper follow evolution...
Two-dimensional (2D) quantum antiferromagnets are of great fundamental interest because the presence fluctuations can lead to novel excitations and ground states.Only little is known about effects applied magnetic fields on 2D square-lattice antiferromagnets.Using neutron scattering technique, we studied excitation spectrum S=1/2 squarelattice Heisenberg antiferromagnet Cu(pz)2(ClO4)2 [1] up one third saturation field.Inelastic measurements performed at zero field show 11.5(7)% dispersion...