Publications related to Multi-triplet bound states and finite-temperature dynamics in highly frustrated quantum spin ladders

Schwinger-boson approach to the kagome antiferromagnet with Dzyaloshinskii-Moriya interactions: Phase diagram and dynamical structure factors

We have obtained the zero-temperature phase diagram of the kagomé antiferromagnet with Dzyaloshinskii-Moriya interactions in Schwinger-boson mean-field theory. We find quantum phase transitions (first or second order) between different topological spin-liq ...

2010

Field-controlled magnetic order in the quantum spin-ladder system (Hpip)2CuBr4

Henrik Moodysson Rønnow, Bruce Normand, Christian Rüegg, Joël Mesot, Pierre Bouillot, Thierry Giamarchi, Daniel Biner

Neutron diffraction is used to investigate the field-induced, antiferromagnetically ordered state in the two-leg spin-ladder material (Hpip)(2)CuBr4. This "classical" phase, a consequence of weak interladder coupling, is nevertheless highly unconventional: ...

2009

Theory of the Field-Induced BEC in the Frustrated Spin-1/2 Dimer Compound BaCuSi2O6

Frédéric Mila, Nicolas Laflorencie

Building on recent neutron and NMR experiments, we investigate the field-induced exotic criticality observed in the frustrated compound BaCuSi2O6 using a frustrated model with two types of bilayers. A semiclassical treatment of the effective hard-core boso ...

2009

Magnetic-Field-Induced Soft-Mode Quantum Phase Transition in the High-Temperature Superconductor La1.855Sr0.145CuO4: An Inelastic Neutron-Scattering Study

Henrik Moodysson Rønnow, Joël Mesot, Johan Juul Chang

Inelastic neutron-scattering experiments on the high-temperature superconductor La1.855Sr0.145CuO4 reveal a magnetic excitation gap Delta that decreases continuously upon application of a magnetic field perpendicular to the CuO2 planes. The gap vanishes at ...

2009

Scale-Free Antiferromagnetic Fluctuations in the s=1/2 Kagome Antiferromagnet Herbertsmithite

Henrik Moodysson Rønnow, Julian Piatek, Goran Nilsen

Neutron spectroscopy and diffuse neutron scattering on herbertsmithite [ZnCu3(OH)(6)Cl-2], a near-ideal realization of the s=1/2 kagome antiferromagnet, reveal the hallmark property of a quantum spin liquid: instantaneous short-ranged antiferromagnetic cor ...

2009

Exotic phases of quantum frustrated magnets

Julien Dorier

In this work, we study two examples of frustrated magnetic systems whose degrees of freedom are spins (or pseudo-spins) on two-dimensional lattices. The first part presents the results obtained for the quantum compass model on a square lattice. This model ...

EPFL2008

Thermal destruction of chiral order in a two-dimensional model of coupled trihedra

Pascal Pierre André Viot

We introduce a minimal model describing the physics of classical two-dimensional (2D) frustrated Heisenberg systems, where spins order in a nonplanar way at T=0. This model, consisting of coupled trihedra (or Ising-RP3 model), encompasses Ising (chiral) de ...

2008

Chromium at high pressures: Weak coupling and strong fluctuations in an itinerant antiferromagnet

Henrik Moodysson Rønnow

The spin- and charge-density-wave order parameters of the itinerant antiferromagnet chromium are directly measured with nonresonant x-ray diffraction as the system is driven toward its quantum critical point with high pressure using a diamond anvil cell. T ...

AMER PHYSICAL SOC2008

Muon spin spectroscopy evidence of a charge density wave in magnetite below the Verwey transition

Helmuth Berger

We present muon spectroscopy data on a Fe3O4 single crystal, revealing different spin precession patterns in five distinct temperature ranges. A careful analysis of the local field and its straightforward modeling obtains surprisingly good agreement with e ...

2008

From quantum glass to addressable spin clusters in the model magnet LiHoxY1−xF4

Tatjana Hählen

This report describes an AC-susceptibility study on

LiHo_xY_{1−x}F_4

.

LiHo_xY_{1−x}F_4 has different phases depending on the concentration x of holmium. Pure

LiHoF_4

is a ferromagnet, at concentrations of

x \approx 0.20$ it is a spin glass and at con ...

2007

Multi-triplet bound states and finite-temperature dynamics in highly frustrated quantum spin ladders

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Schwinger-boson approach to the kagome antiferromagnet with Dzyaloshinskii-Moriya interactions: Phase diagram and dynamical structure factors

Field-controlled magnetic order in the quantum spin-ladder system (Hpip)2CuBr4

Theory of the Field-Induced BEC in the Frustrated Spin-1/2 Dimer Compound BaCuSi2O6

Magnetic-Field-Induced Soft-Mode Quantum Phase Transition in the High-Temperature Superconductor La1.855Sr0.145CuO4: An Inelastic Neutron-Scattering Study

Scale-Free Antiferromagnetic Fluctuations in the s=1/2 Kagome Antiferromagnet Herbertsmithite

Exotic phases of quantum frustrated magnets

Thermal destruction of chiral order in a two-dimensional model of coupled trihedra

Chromium at high pressures: Weak coupling and strong fluctuations in an itinerant antiferromagnet

Muon spin spectroscopy evidence of a charge density wave in magnetite below the Verwey transition

From quantum glass to addressable spin clusters in the model magnet LiHoxY1−xF4

Schwinger-boson approach to the kagome antiferromagnet with Dzyaloshinskii-Moriya interactions: Phase diagram and dynamical structure factors

Thermal destruction of chiral order in a two-dimensional model of coupled trihedra

Field-controlled magnetic order in the quantum spin-ladder system (Hpip)2CuBr4

Chromium at high pressures: Weak coupling and strong fluctuations in an itinerant antiferromagnet

Muon spin spectroscopy evidence of a charge density wave in magnetite below the Verwey transition

From quantum glass to addressable spin clusters in the model magnet LiHoxY1−xF4

Magnetic-Field-Induced Soft-Mode Quantum Phase Transition in the High-Temperature Superconductor La1.855Sr0.145CuO4: An Inelastic Neutron-Scattering Study

Exotic phases of quantum frustrated magnets

Theory of the Field-Induced BEC in the Frustrated Spin-1/2 Dimer Compound BaCuSi2O6

Scale-Free Antiferromagnetic Fluctuations in the s=1/2 Kagome Antiferromagnet Herbertsmithite