Terahertz Resonant Emission by Optically Excited Infrared-Active Shear Phonons in KY(MoO).

The generation of monochromatic electromagnetic radiation in the terahertz (THz) frequency range has remained a challenging task for many decades. Here, the emission of monochromatic sub-THz radiation by optical phonons in the dielectric material KY(MoO) is demonstrated. The layered crystal structure of KY(MoO) causes infrared-active shear lattice vibrations to have energies below 3.

Magnetization reversal through an antiferromagnetic state.

Magnetization reversal in ferro- and ferrimagnets is a well-known archetype of non-equilibrium processes, where the volume fractions of the oppositely magnetized domains vary and perfectly compensate each other at the coercive magnetic field. Here, we report on a fundamentally new pathway for magnetization reversal that is mediated by an antiferromagnetic state. Consequently, an atomic-scale compensation of the magnetization is realized at the coercive field, instead of the mesoscopic or macroscopic domain cancellation in canonical reversal processes.

Magnetic anisotropy in CsGd(MoO)probed by EPR spectroscopy.

Here we report electron paramagnetic resonance (EPR) study of rare-earth paramagnet CsGd(MoO). Multifrequency EPR measurements allowed us to directly probe the splitting of the lowestSmultiplet of Gdion and revealed the rhombic type of single-ion anisotropy. An easy-axis anisotropy approximation with a rhombic distortion of the Gdlocal environment describes obtained EPR spectra and yield energies ofSsplitting.

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 SrCoVO in strong longitudinal magnetic fields.

Magnetoquantum Oscillations at THz Frequencies in InSb.

The ac magnetoconductance of bulk InSb at THz frequencies in high magnetic fields, as measured by the transmission of THz radiation, shows a field-induced transmission, which at high temperatures (≈100  K) is well explained with classical magnetoplasma effects (helicon waves). However, at low temperatures (4 K), the transmitted radiation intensity shows magnetoquantum oscillations that represent the Shubnikov-de Haas effect at THz frequencies. At frequencies above 0.