No abstract

The existence of backscattering-immune spin-wave modes is demonstrated in magnetic thin films of nano-scale thickness. Our results reveal that chiral Magneto Static Surface Waves (cMSSWs), which propagate perpendicular to the magnetization direction in an in-plane magnetized thin film, are robust against backscattering from surface defects. cMSSWs are protected against various types of surface inhomogeneities and defects as long as their frequency lies inside the gap of the volume modes. Our explanation is independent of the topology of the modes and predicts that this robustness is a consequence of symmetry breaking of the dynamic magnetic fields of cMSSWs due to the off-diagonal part of the dipolar interaction tensor, which is present both for long-(dipole dominated) and short-wavelength (exchange dominated) spin waves. Micromagnetic simulations confirm the robust character of the cMSSWs. Our results open a new direction in designing highly efficient magnonic logic elements and devices employing cMSSWs in nano-scale thin films.

The Mathisson-Papapetrou-Dixon equations for a massive spinning test particle in plane gravitational waves are analysed and explicit solutions constructed in terms of solutions of certain linear ordinary differential equations. For harmonic waves this system reduces to a single equation of Mathieu-Hill type. In this case spinning particles may exhibit parametric excitation by gravitational fields. For a spinning test particle scattered by a gravitational wave pulse, the final energy-momentum of the particle may be related to the width, height, polarisation of the wave and spin orientation of the particle.

The motion of a classical spinning test particle in the field of a weak plane gravitational wave is studied. It is found that the characteristic dimensions of the particle's orbit is sensitive to the ratio of the spin to the mass of the particle. The results are compared with the corresponding motion of a particle without spin.

Myocardial infarction is one of the major causes of mortality throughout the world. Cardiac scaffolds are tissueengineered structures for the treatment of myocardial infarction and are employed for tissue support and cell delivery to the injured region. In this study, we fabricated nanostructured graphene foams as porous and biocompatible cardiac tissue-engineering scaffolds. Three-dimensional graphene foam and two-dimensional graphene were fabricated using chemical vapor deposition. We showed that the nickel etching had no effect on the structural appearance of the threedimensional graphene foam. Toxicity of the prepared samples was evaluated on human umbilical vein endothelial cells at 48 h and 72 h and showed no toxic effects on the viability of the cells. Moreover, both samples supported the adhesion and growth of neonatal cardiomyocytes with three-dimensional graphene foam showing a more extensive effect on the expression of the cardiac genes involved in muscle contraction and relaxation (troponin-T) and gap junctions (Connexin 43). Hence, conductive three-dimensional graphene foam with its large surface area and specific surface properties could provide a promising platform for cardiac tissue engineering.