From confined spinons to emergent fermions: Observation of elementary magnetic excitations in a transverse-field Ising chain

We report on spectroscopy study of elementary magnetic excitations in an Ising-like antiferromagnetic chain compound SrCo$_2$V$_2$O$_8$ as a function of temperature and applied transverse magnetic field up to 25 T. An optical as well as an acoustic branch of confined spinons, the elementary excitations at zero field, are identified in the antiferromagnetic phase below the N\'{e}el temperature of 5 K and described by a one-dimensional Schr\"{o}dinger equation. The confinement can be suppressed by an applied transverse field and a quantum disordered phase is induced at 7 T. In this disordered paramagnetic phase, we observe three emergent fermionic excitations with different transverse-field dependencies. The nature of these modes is clarified by studying spin dynamic structure factor of a 1D transverse-field Heisenberg-Ising (XXZ) model using the method of infinite time evolving block decimation. Our work reveals emergent quantum phenomena and provides a concrete system for testifying theoretical predications of one-dimension quantum spin models.Comment: 8 pages and 6 figure

The Magnetoelastic Distortion of Multiferroic BiFeO3_3 in the Canted Antiferromagnetic State

Using THz spectroscopy, we show that the spin-wave spectrum of multiferroic BiFeO$_3$ in its high-field canted antiferromagnetic state is well described by a spin model that violates rhombohedral symmetry. We demonstrate that the monoclinic distortion of the canted antiferromagnetic state is induced by the single-ion magnetoelastic coupling between the lattice and the two nearly anti-parallel spins. The revised spin model for BiFeO$_3$ contains two new single-ion anisotropy terms that violate rhombohedral symmetry and depend on the direction of the magnetic field.Comment: 28 pages (main & supplementary), 2 figures (main article), 15 figures (supplementary material

An unforeseen polymorph of coronene by the application of magnetic fields during crystal growth

Contains fulltext : 158779.pdf (publisher's version ) (Open Access

Programmed helical phthalocyanine architectures

Contains fulltext : 19325_proghepha.pdf (publisher's version ) (Open Access)111 p

Handling Linear Precedence Constraints By Unification

Linear precedence (LP) rules are widely used for stating word order principles. They have been adopted as constraints by HPSG but no encoding in the formalism has been provided. Since they only order siblings, they are not quite adequate, at least not for German. We propose a notion of LP constraints that applies to linguistically motivated branching domains such as head domains. We show a type-based encoding in an HPSG-style formalism that supports processing. The encoding can be achieved by a compilation step

Colloidal Stability of Aqueous Ferrofluids at 10 T

Contains fulltext : 224902.pdf (publisher's version ) (Open Access

Magnetic Sedimentation Velocities and Equilibria in Dilute Aqueous Ferrofluids

Contains fulltext : 224931.pdf (publisher's version ) (Open Access

Colloidal Stability of Aqueous Ferrofluids at 10 T

Magnetic density separation is an emerging recycling technology by which several different waste materials-from plastic products, electronics, or other-can be sorted in a single continuous processing step. Larger-scale installations will require ferrofluids that remain stable at several teslas, high magnetic fields at which colloidal stability was not investigated before. Here we optically monitor the concentration profile of iron oxide nanoparticles in aqueous ferrofluids at a field of 10 T and a gradient of 100 T/m. The sedimentation velocities and equilibrium concentration profiles inform on maintenance or breakdown of colloidal stability, which depends on the concentration and magnetic coupling energy of the nanoparticles. Comparison with results obtained with a small neodymium magnet indicate that stability at moderate fields is predictive of stability at much higher fields, which facilitates the development of new ferrofluids dedicated to magnetic density separation