Publications
Management of photo-excited carriers in light trapping nanostructured Si solar cells
Nanostructures significantly improve light trapping capability of Si absorbers and also enhance light intensity near the surface. Such surface concentrated light can boost the carrier collection efficiency of the nanostructure-based solar cells. © 2015 OSA.
Biostructural Science Inspired by Next-Generation X-Ray Sources
Next-generation synchrotron radiation sources, such as X-ray free-electron lasers, energy recovery linacs, and ultra-low-emittance storage rings, are catalyzing novel methods of biomolecular microcrystallography and solution scattering. These methods are described and future trends are predicted. Importantly, there is a growing realization that serial microcrystallography and certain cutting-edge solution scattering experiments can be performed at existing storage ring sources by utilizing new technology.
The effect of shear flow on the rotational diffusion of a single axisymmetric particle
Understanding the orientation dynamics of anisotropic colloidal particles is important for suspension rheology and particle self-assembly. However, even for the simplest case of dilute suspensions in shear flow, the orientation dynamics of non-spherical Brownian particles are poorly understood. Here we analytically calculate the time-dependent orientation distributions for non-spherical axisymmetric particles confined to rotate in the flow-gradient plane, in the limit of small but non-zero Brownian diffusivity.
Computationally efficient dielectric calculations of molecular crystals
The microscopic dielectric response is a key quantity for electronic materials such as organic semiconductors. Calculations of this response for molecular crystals are currently either expensive or rely on extreme simplifications such as multipole expansions which lack microscopic detail. We present an alternate approach using a microscopic analogue of the Clausius-Mossotti equation, which constructs the dielectric response of a crystal from an eigenvalue decomposition of the dielectric response of individual molecules.
Ordered mesoporous titania from highly amphiphilic block copolymers: Tuned solution conditions enable highly ordered morphologies and ultra-large mesopores
Crystalline transition metal oxides with controlled mesopore architectures are in increasing demand to enhance the performance of energy conversion and storage devices. Solution based block copolymer self-assembly routes to achieve ordered mesoporous and crystalline titania have been studied for more than a decade, but have so far mostly been limited to water and alcohol dispersible polymers. This constraint has limited the accessible morphology space as well as structural dimensions.
Dynamic regulation of transcription factors by nucleosome remodeling
The chromatin landscape and promoter architecture are dominated by the interplay of nucleosome and transcription factor (TF) binding to crucial DNA sequence elements. However, it remains unclear whether nucleosomes mobilized by chromatin remodelers can influence TFs that are already present on the DNA template. In this study, we investigated the interplay between nucleosome remodeling, by either yeast ISW1a or SWI/SNF, and a bound TF. We found that a TF serves as a major barrier to ISW1a remodeling, and acts as a boundary for nucleosome repositioning.
Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-T c cuprates
The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high T c. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes.
Enhancement of the anti-damping spin torque efficacy of platinum by interface modification
We report a strong enhancement of the efficacy of the spin Hall effect (SHE) of Pt for exerting anti-damping spin torque on an adjacent ferromagnetic layer by the insertion of ?0.5?nm layer of Hf between a Pt film and a thin, ≤2?nm, Fe60Co20B20 ferromagnetic layer. This enhancement is quantified by measurement of the switching current density when the ferromagnetic layer is the free electrode in a magnetic tunnel junction.
Erratum to: Indivisibility of Electron Bubbles in Helium [Journal of Low Temperature Physics, 123, 1, 2, (2001), DOI:10.1023/A:1017534129860]
Entanglement Entropy of the ν=1/2 Composite Fermion Non-Fermi Liquid State
The so-called "non-Fermi liquid" behavior is very common in strongly correlated systems. However, its operational definition in terms of "what it is not" is a major obstacle for the theoretical understanding of this fascinating correlated state. Recently there has been much interest in entanglement entropy as a theoretical tool to study non-Fermi liquids. So far explicit calculations have been limited to models without direct experimental realizations.