arXiv subjects

J. R. Holt

Publications and source records attributed to J. R. Holt.

2 recordsLinked to original sources

arXiv2015

High resolution three dimensional structural microscopy by single angle Bragg ptychography

We present an efficient method of imaging 3D nanoscale lattice behavior and strain fields in crystalline materials with a new methodology -- three dimensional Bragg projection ptychography (3DBPP). In this method, the 2D sample structure information encoded in a coherent high-angle Bragg peak measured at a fixed angle is combined with the real-space scanning probe positions to reconstruct the 3D sample structure. This work introduces an entirely new means of three dimensional structural imaging of nanoscale materials and eliminates the experimental complexities associated with rotating nanoscale samples. We present the framework for the method and demonstrate our approach with a numerical demonstration, an analytical derivation, and an experimental reconstruction of lattice distortions in a component of a nanoelectronic prototype device.

cond-mat.mtrl-sci↗

arXiv2007

Rotating molecules in optical lattices, alignment and monopole crystals

The recent progress towards production of near-ground state quantum-degenerate molecules raises the issue of how such "small" molecules behave in an optical lattice. In this Letter we show that the coupling of the molecular orientation to the local electric field direction will provide severalnew phenomena. In the case where the lasers forming different crystallographic directions of the lattice are incoherent, the orientation of the molecules is conserved (for L = 1) and a novel form of anisotropic superfluidity can be expected. When the lasers are coherent, and the optical lattice is such that the splitting of the rotational levels is large compared to the centre of mass energies,an adiabaic description of the molecular orientation is appropriate. This leads to geometric vector potentials, pseudo-magnetic monopoles and a frustrated band structure with degenerate minima.

cond-mat.other↗