A. T. M. Nazmul Islam

Spin and orbital order in the vanadium spinel MgV2O4

octahedra and a low temperature space group (I4m2) that maintains the mirrorplane symmetry. The magnetic structure that develops below 42K consists of antiferromagneticchains with a strongly reduced moment while inelastic neutron scattering reveals one-dimensionalbehavior and a single band of excitations. The implications of these results are discussed in terms ofvarious orbital ordering scenarios. We conclude that although spin-orbit coupling must be signi cantto maintain the mirror plane symmetry, the trigonal distortion is large enough to mix the 3d levelsleading to a wave function of mixed real and complex orbitals.

Physical realization of a quantum spin liquid based on a complex frustration mechanism

A detailed and systematic study of Ca10Cr7O28 reveals all the hallmarks of spin-liquid behaviour, in spite of the compound’s unusually complex structure.

Experimental observation of Bethe strings

Almost a century ago, string states—complex bound states of magnetic excitations—were predicted to exist in one-dimensional quantum magnets. However, despite many theoretical studies, the experimental realization and identification of string states in a condensed-matter system have yet to be achieved. Here we use high-resolution terahertz spectroscopy to resolve string states in the antiferromagnetic Heisenberg–Ising chain SrCo2V2O8 in strong longitudinal magnetic fields. In the field-induced quantum-critical regime, we identify strings and fractional magnetic excitations that are accurately described by the Bethe ansatz. Close to quantum criticality, the string excitations govern the quantum spin dynamics, whereas the fractional excitations, which are dominant at low energies, reflect the antiferromagnetic quantum fluctuations. Today, Bethe’s result is important not only in the field of quantum magnetism but also more broadly, including in the study of cold atoms and in string theory; hence, we anticipate that our work will shed light on the study of complex many-body systems in general.

Magnetic Hamiltonian and phase diagram of the quantum spin liquid Ca 10 Cr 7 O 28

A spin liquid is a new state of matter with topological order where the spin moments continue to fluctuate coherently down to the lowest temperatures rather than develop static long-range magnetic order as found in conventional magnets. For spin liquid behavior to arise in a material the magnetic Hamiltonian must be ``frustrated, where the combination of lattice geometry, interactions, and anisotropies gives rise to competing spin arrangements in the ground state. Theoretical Hamiltonians which produce spin liquids are spin ice, the Kitaev honeycomb model, and the kagome antiferromagnet. Spin liquid behavior, however, in real materials is rare because they can only approximate these Hamiltonians and often have weak higher-order terms that destroy the spin liquid state.

Multiple lattice instabilities resolved by magnetic-field and disorder sensitivities inMgV2O4

{mathrm{Ca}}_{10}{mathrm{Cr}}_{7}{mathrm{O}}_{28}

Coupled spin-lattice fluctuations in a compound with orbital degrees of freedom: the Cr based dimer system Sr3Cr2O8

is a new quantum spin liquid candidate with magnetic

Crystal growth, structure and magnetic properties of Ca10Cr7O28

{mathrm{Cr}}^{5+}

Softened magnetic excitations in the s = 3/2 distorted triangular antiferromagnet α-CaCr2O4.

ions that possess quantum spin number

Absorption Enhancement for Ultrathin Solar Fuel Devices with Plasmonic Gratings

S=textonehalf{}

Unconventional Growth Mechanism in Optical Traveling Solvent Floating Zone Growth of Large β-CuNb2O6 Single Crystals

. The spins are entirely dynamic in the ground state and the excitation spectrum is broad and diffuse, as is typical of spinons which are the excitations of a spin liquid. In this paper we determine the Hamiltonian of