Publications de Nicolas Laflorencie

Investigating field-induced magnetic order in Han purple by neutron scattering up to 25.9 T

Philippe Heller, Frédéric Mila, Bruce Normand, Nicolas Laflorencie

BaCuSi2O6 is a quasi-two-dimensional (2D) quantum antiferromagnet containing three different types of stacked, square-lattice bilayer hosting spin-1/2 dimers. Although this compound has been studied extensively over the last two decades, the critical appli ...

2022

Multiple Magnetic Bilayers and Unconventional Criticality without Frustration in BaCuSi2O6

Frédéric Mila, Bruce Normand, Nicolas Laflorencie, Gregory Scott Tucker, Christian Rüegg

The dimerized quantum magnet BaCuSi2O6 was proposed as an example of "dimensional reduction" arising near the magnetic-field-induced quantum critical point (QCP) due to perfect geometrical frustration of its interbilayer interactions. We demonstrate by hig ...

2020

Spatially resolved magnetization in the Bose-Einstein condensed state of BaCuSi2O6: Evidence for imperfect frustration

Frédéric Mila, Nicolas Laflorencie

In order to understand the nature of the two-dimensional Bose-Einstein condensed (BEC) phase in BaCuSi2O6, we performed detailed Cu-63 and Si-29 NMR above the critical magnetic field, H-c1 = 23.4 T. The two different alternating layers present in the syste ...

2013

Semiclassical approach to ground-state properties of hard-core bosons in two dimensions

Frédéric Mila, Tommaso Coletta, Nicolas Laflorencie

Motivated by some inconsistencies in the way quantum fluctuations are included beyond the classical treatment of hard-core bosons on a lattice in the recent literature, we revisit the large-S semiclassical approach to hard-core bosons on the square lattice ...

2012

Phase separation versus supersolid behavior in frustrated antiferromagnets

Jean-David Picon, Frédéric Mila, Nicolas Laflorencie

We investigate the competition between spin supersolidity and phase separation in a frustrated spin-half model of weakly coupled dimers. We start by considering systems of hard-core bosons on the square lattice, onto which the low-energy physics of the her ...

2011

Condensate-Free Superfluid Induced by the Frustrated Proximity Effect

Frédéric Mila, Nicolas Laflorencie

Since the discovery of superfluidity in He-4 and Landau's phenomenological theory, the relationship between Bose condensation and superfluidity has been intensely debated. He-4 is known by now to be both superfluid and condensed at low temperature, and mor ...

2011

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

Kondo screening cloud and charge staircase in one-dimensional mesoscopic devices

Nicolas Laflorencie

We propose that the finite size of the Kondo screening cloud, xi(K), can be probed by measuring the charge quantization in a one-dimensional system coupled to a small quantum dot. When the chemical potential mu in the system is varied at zero temperature, ...

2008

Mechanisms for spin supersolidity in S=1/2 spin-dimer antiferromagnets

Jean-David Picon, Frédéric Mila, Nicolas Laflorencie

Using perturbative expansions and the contractor renormalization (CORE) algorithm, we obtain effective hard-core bosonic Hamiltonians describing the low-energy physics of S=1/2 spin-dimer antiferromagnets known to display supersolid phases under an applied ...

2008

Quantum and Thermal Transitions Out of the Supersolid Phase of a 2D Quantum Antiferromagnet

Frédéric Mila, Nicolas Laflorencie

We investigate the thermodynamic properties of a field-induced supersolid phase in a 2D quantum antiferromagnet model. Using quantum Monte Carlo simulations, a very rich phase diagram is mapped out in the temperature—magnetic-field plane, with an extended ...

2007

Correlation amplitude and entanglement entropy in random spin chains

Nicolas Laflorencie

Using strong-disorder renormalization group, numerical exact diagonalization, and quantum Monte Carlo methods, we revisit the random antiferromagnetic XXZ spin-1/2 chain focusing on the long-length and ground-state behavior of the average time-independent ...

2007