Nicolas Gauthier

Candidate quantum spin ice in the pyrochlore Pr2Hf2O7

We report the low temperature magnetic properties of the pyrochlore

Experimental signatures of emergent quantum electrodynamics in Pr 2 Hf 2 O 7

{\mathrm{Pr}}_{2}{\mathrm{Hf}}_{2}{\mathrm{O}}_{7}

Field dependence of the magnetic correlations of the frustrated magnet SrDy2O4

. Polycrystalline and single-crystal samples are investigated using time-of-flight neutron spectroscopy and macroscopic measurements, respectively. The crystal-field splitting produces a non-Kramers doublet ground state for

Absence of long-range order in the frustrated magnet SrDy2O4 due to trapped defects from a dimensionality crossover

{\mathrm{Pr}}^{3+}

Unconventional field induced phases in a quantum magnet formed by free radical tetramers

, with Ising-like anisotropy. Below 0.5 K ferromagnetic correlations develop, which suggests that the system enters a spin-ice-like state associated with the metamagnetic behavior observed at

Investigation of the commensurate magnetic structure in the heavy-fermion compound CePt2In7 using magnetic resonant x-ray diffraction

{\ensuremath{\mu}}_{0}{H}_{c}\ensuremath{\sim}2.4

Spin dynamics and magnetoelectric coupling mechanism of Co4Nb2O9

T. In this regime, the development of a discrete inelastic excitation in the neutron spectra indicates the appearance of spin dynamics that are likely related to cooperative quantum fluctuations.

Coexistence of magnetic fluctuations and long-range order in the one-dimensional J1−J2 zigzag chain materials BaDy2O4 and BaHo2O4

In a quantum spin liquid, the magnetic moments of the constituent electron spins evade classical long-range order to form an exotic state that is quantum entangled and coherent over macroscopic length scales1,2. Such phases offer promising perspectives for device applications in quantum information technologies, and their study can reveal new physics in quantum matter. Quantum spin ice is an appealing proposal of one such state, in which the fundamental ground state properties and excitations are described by an emergent U(1) lattice gauge theory3–7. This quantum-coherent regime has quasiparticles that are predicted to behave like magnetic and electric monopoles, along with a gauge boson playing the role of an artificial photon. However, this emergent lattice quantum electrodynamics has proved elusive in experiments. Here we report neutron scattering measurements of the rare-earth pyrochlore magnet Pr2Hf2O7 that provide evidence for a quantum spin ice ground state. We find a quasi-elastic structure factor with pinch points—a signature of a classical spin ice—that are partially suppressed, as expected in the quantum-coherent regime of the lattice field theory at finite temperature. Our result allows an estimate for the speed of light associated with magnetic photon excitations. We also reveal a continuum of inelastic spin excitations, which resemble predictions for the fractionalized, topological excitations of a quantum spin ice. Taken together, these two signatures suggest that the low-energy physics of Pr2Hf2O7 can be described by emergent quantum electrodynamics. If confirmed, the observation of a quantum spin ice ground state would constitute a concrete example of a three-dimensional quantum spin liquid—a topical state of matter that has so far mostly been explored in lower dimensionalities.A detailed and systematic neutron scattering study of rare-earth pyrochlore magnet Pr2Hf2O7 provides evidence for a quantum spin ice state, and emergent lattice quantum electrodynamics consistent with theoretical predictions.

Evidence of Bose-Einstein condensation in a quantum magnet formed by free radical tetramers

The frustrated magnet SrDy

Experimental signatures of emergent quantum electrodynamics in a quantum spin ice

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