Giant magnetocaloric effect in spin supersolid candidate NaBaCo(PO).

Supersolid, an exotic quantum state of matter that consists of particles forming an incompressible solid structure while simultaneously showing superfluidity of zero viscosity, is one of the long-standing pursuits in fundamental research. Although the initial report of He supersolid turned out to be an artefact, this intriguing quantum matter has inspired enthusiastic investigations into ultracold quantum gases. Nevertheless, the realization of supersolidity in condensed matter remains elusive.

Topological magnons driven by the Dzyaloshinskii-Moriya interaction in the centrosymmetric ferromagnet MnGe.

The phase of the quantum-mechanical wave function can encode a topological structure with wide-ranging physical consequences, such as anomalous transport effects and the existence of edge states robust against perturbations. While this has been exhaustively demonstrated for electrons, properties associated with the elementary quasiparticles in magnetic materials are still underexplored. Here, we show theoretically and via inelastic neutron scattering experiments that the bulk ferromagnet MnGe hosts gapped topological Dirac magnons.

Topological magnon insulators in two-dimensional van der Waals ferromagnets CrSiTe and CrGeTe: Toward intrinsic gap-tunability.

The bosonic analogs of topological insulators have been proposed in numerous theoretical works, but their experimental realization is still very rare, especially for spin systems. Recently, two-dimensional (2D) honeycomb van der Waals ferromagnets have emerged as a new platform for topological spin excitations. Here, via a comprehensive inelastic neutron scattering study and theoretical analysis of the spin-wave excitations, we report the realization of topological magnon insulators in CrXTe (X = Si, Ge) compounds.

Combined Arrhenius-Merz Law Describing Domain Relaxation in Type-II Multiferroics.

Electric fields were applied to multiferroic TbMnO_{3} single crystals to control the chiral domains, and the domain relaxation was studied over 8 decades in time by means of polarized neutron scattering. A surprisingly simple combination of an activation law and the Merz law describes the relaxation times in a wide range of electric field and temperature with just two parameters, an activation-field constant and a characteristic time representing the fastest possible inversion. Over the large part of field and temperature values corresponding to almost 6 orders of magnitude in time, multiferroic domain inversion is thus dominated by a single process, the domain wall motion.