Related papers: Non-monotonic zero point entropy in diluted spin i…
Spin ice illustrates many unusual magnetic properties, including zero point entropy, emergent monopoles and a quasi liquid-gas transition. To reveal the quantum spin dynamics that underpin these phenomena is an experimental challenge. Here…
$\gamma$-${\rm Ba}_{3}{\rm CoNb}_{2}{\rm O}_{9}$ realizes a disordered simple-cubic spin-$1/2$ lattice in which Co$^{2+}$ ions randomly occupy one third of the sites, placing the system close to the site-percolation threshold for magnetic…
The spin ice compound Dy$_2$Ti$_2$O$_7$ is well-known to realise a three-dimensional Coulomb spin liquid with magnetically charged monopole excitations. Its fate at low temperatures, however, remains an intriguing open question. Based on a…
We study experimentally and numerically the dynamics of the spin ice material Dy$_2$Ti$_2$O$_7$ in the low temperature ($T$) and moderate magnetic field ($\mathbf{B}$) regime ($T\in[0.1,1.7]K$, $B\in[0,0.3]T$). Our objective is to…
We analyze the entanglement entropy in the Lipkin-Meshkov-Glick model, which describes mutually interacting spins half embedded in a magnetic field. This entropy displays a singularity at the critical point that we study as a function of…
Ba$_3$Mn$_2$O$_8$ is a geometrically frustrated spin dimer compound. We investigate the effect of site disorder on the zero field phase diagram of this material by considering the solid solution Ba$_{3}$(Mn$_{1-x}$V$_{x}$)$_{2}$O$_{8}$,…
In this work, we explore the magnetic behavior of diluted spin-ice systems, where magnetic moments are randomly removed at various concentrations. We concentrate on features in which the effect of long range dipolar interactions (usually…
We study the dipolar spin-ice model at fixed density of single excitations, $\rho$, using a Monte Carlo algorithm where processes of creation and annihilation of such excitations are banned. In the limit of $\rho$ going to zero, this model…
The dynamics of a central spin-1/2 in presence of a local magnetic field and a bath of N spin-1/2 particles is studied in the thermodynamic limit. The interaction between the spins is Heisenberg XY type and the bath is considered to be a…
Spin ice is a paradigmatic frustrated system famous for the emergence of magnetic monopoles and a large magnetic entropy at low temperatures. It exhibits unusual behavior in the presence of an external magnetic field as a result of the…
The mathematics of gauge theories lies behind many of the most profound advances in physics in the last 200 years, from Maxwell's theory of electromagnetism to Einstein's theory of general relativity. More recently it has become clear that…
Spin crossover materials contain metal ions that can access two spin-states: one low-spin (LS), the other high-spin (HS). We propose that frustrated elastic interactions can give rise to spin-state ices -- phases of matter without…
Magnetic monopole quasiparticles in spin ice materials hold the potential for exploring new frontiers of physics that extend beyond Maxwell's equations. We have previously proposed a two-dimensional magnetic monopole gas (2DMG), confined at…
Artificial spin ices have transcended their origins in frustrated rare-earth pyrochlores to become a versatile platform for engineering exotic states of matter. Across diverse implementations, from nanomagnets and superconducting vortices…
$\rm{Sr_2CuTe_{0.5}W_{0.5}O_6}$ is a square-lattice magnet with super-exchange between S=1/2 $\rm{Cu^{2+}}$ spins mediated by randomly distributed Te and W ions. Here, using sub-K temperature and 20 $\rm{\mu}$eV energy resolution neutron…
We study the low-temperature behaviour of spin ice when uniaxial pressure induces a tetragonal distortion. There is a phase transition between a Coulomb liquid and a fully magnetised phase. Unusually, it combines features of discontinuous…
We calculate exactly the time-dependent reduced density matrix for the central spin in the central-spin model with homogeneous Heisenberg couplings. Therefrom, the dynamics and the entanglement entropy of the central spin are obtained. A…
We present a combined analytical and numerical study of the entropy as a function of magnetization for an orientable 2D spin-ice model that exhibits a Kasteleyn transition. The model that we use is related to the well known six-vertex model…
Spin ice presents a typical example of classical spin liquid, where conserved magnetic fluxes emerge from microscopic spin degrees of freedom. In this letter, we investigate the effect of perturbation by magnetic charge disorder in…
Dynamics of Ising models is a much studied phenomenon and has emerged as a rich field of present-day research. An important dynamical feature commonly studied is the quenching phenomenon below the critical temperature. In this thesis we…