https://www.andrew.cmu.edu/user/dl0p/laughlin/pdf/PMS.pdf

Amorphous and nanocrystalline materials for applications as soft magnets

Static critical phenomena in ferromagnets with quenched disorder

Experiments on ultrathin anisotropic arrays of subwavelength optical antennas display out-of-plane refraction. A powerful three-dimensional (3D) extension of the recently demonstrated generalized laws of refraction and reflection shows that the interface imparts a tangential wavevector to the incident light leading to anomalous beams, which in general are noncoplanar with the incident beam. The refracted beam direction can be controlled by varying the angle between the plane of incidence and the antenna array.

http://www.zenogaburro.it/papers/2012_Nano_Aieta_OutOfPlane.pdf

Out-of-Plane Reflection and Refraction of Light by Anisotropic Optical Antenna Metasurfaces with Phase Discontinuities

We investigate the transmission of evanescent waves through a slab of photonic crystal and explore the recently suggested possibility of focusing light with subwavelength resolution. The amplification of near-field waves is shown to rely on resonant coupling mechanisms to surface photon bound states, and the negative refractive index is only one way of realizing this effect. It is found that the periodicity of the photonic crystal imposes an upper cutoff to the transverse wave vector of evanescent waves that can be amplified, and thus a photonic-crystal superlens is free of divergences even in the lossless case. A detailed numerical study of the optical image of such a superlens in two dimensions reveals a subtle and very important interplay between propagating waves and evanescent waves on the final image formation. Particular features that arise due to the presence of near-field light are discussed.

/pdf/subwavelength-imaging-in-photonic-crystals-1cessc1emt.pdf

Subwavelength imaging in photonic crystals

Nanoparticles and filled nanocapsules

Neutron scattering experiments were performed on the single-crystalline DyB 2 C 2 under magnetic fields in order to elucidate the magnetic structures of field-induced phases. The measurements in the a * – c * reciprocal lattice plane under the magnetic fields along the [010] direction resulted in finding a new magnetic reflection of 1 0 3/4 in a field-induced phase (phase II ′′ ) in addition to the magnetic reflections that are common to those in the phase under a zero magnetic field (phase III). The magnetic unit cell in phase II ′′ has dimensions of a × a ×4 c , where all the Dy magnetic moments on the AFQ structure have advantageous directions to the magnetic field, and their AFQ couplings with the neighbouring moments along the c -axis are partly broken. This magnetic structure model for phase II ′′ well explains the magnetisation process at 5 K up to 14 T.

Field-Induced Magnetic Structures in Antiferroquadrupolar Ordering Compound DyB2C2

Magnetization measurements were performed on a DyB 2 C 2 single crystal under pressures up to 1.0 GPa in high magnetic fields up to 26 T. At 4.2 K, pressure-induced magnetic phases are found below 8 T along the [1 0 0] axis, which varies for pressures and temperatures.

Magnetization measurements of DyB2C2 under high pressure and high magnetic fields

We performed single-crystal neutron diffraction experiments and electrical resistivity measurements under high pressure on DyB2C2 showing both the antiferroquadrupolar (AFQ) and antiferromagnetic (AFM) orders. The Neel temperature T
 N increases gradually with increasing pressure and saturates at pressures above 5.2 GPa while the AFQ transition temperature T
 Q decreases almost monotonically up to 3.13 GPa and seems to merge with T
 N at around 6–7 GPa. These results indicate that the application of pressure suppresses the AFQ ordering in DyB2C2 and simultaneously enhances the AFM interaction between 4f spins. The suppression of the AFQ ordering can be interpreted as being due to the restriction of the local strain associated with the AFQ transition caused by applying pressure.

High-pressure studies of DyB 2 C 2

Neutron powder diffraction studies have been made for Dy(Cu1−xNix)2Si2 with x=0, 0.06, and 0.1. The diffraction patterns of DyCu2Si2 are consistent with the reported magnetic structure [k=(1/2,0,1/2)], the Neel temperature (TN=10 K) and the Dy magnetic moment (8.2 μB). The diffraction patterns of Dy(Cu0.94Ni0.06)2Si2 and Dy(Cu0.9Ni0.1)2Si2 are interpreted by the same commensurate antiferromagnetic structures with k=(1/2,0,1/2). The Neel temperatures of Dy(Cu0.94Ni0.06)2Si2 and Dy(Cu0.9Ni0.1)2Si2 are determined to be 7.5 and 6.5 K, respectively. The magnetic moments are 6.5 μB/Dy in the Dy(Cu0.94Ni0.06)2Si2 and 6.0 μB/Dy in the Dy(Cu0.9Ni0.1)2Si2. The magnetic moment decreases as the Ni concentration increases, whereas the Dy moment determined by the Mossbauer spectroscopy increases as x increases. There is a strong diffuse peak at the (1/2 0 1/2) position of Dy(Cu0.94Ni0.1)2Si2 which implies the existence of some kinds of short range ordering of Dy moments. This fact suggests that the local crystalline el...

Hideya Onodera

Papers

Field-Induced Magnetic Structures in Antiferroquadrupolar Ordering Compound DyB2C2

Magnetization measurements of DyB2C2 under high pressure and high magnetic fields

High-pressure studies of DyB 2 C 2

Neutron diffraction studies on Dy(Cu1−xNix)2Si2

Anomalous concentration dependence of the Dy moment in Dy1−xYxB2C2 compounds