arXiv subjects

M. Zaid Zaz

Publications and source records attributed to M. Zaid Zaz.

5 recordsLinked to original sources

arXiv2025

On the origins of charge transport in spin crossover complexes

Spin crossover (SCO) complexes are highly promising candidates for a myriad of potential applications in room-temperature electronics; however, as it stands, establishing a clear connection between their spin-state switching and transport properties has been far from trivial. In this Perspective, an effort to unravel the underlying charge transport mechanism in these SCO complexes, via a general theory, is made. The theory presented herein is aimed at providing a unifying picture that explains the widely different trends observed in the spin-crossover-dependent carrier transport properties in the SCO molecular thin film systems.

cond-mat.mtrl-sci↗

arXiv2024

The surface termination of a Fe (III) spin crossover molecular salt

From a comparison of energy dispersive analyses of X-rays (EDAX), the known molecular stoichiometry and X-ray photoemission spectroscopy (XPS), it is evident that the Fe(III) spin crossover salt [Fe(qsal)2Ni(dmit)2] has a preferential surface termination with the Ni(dmit)2 moiety. This preferential surface termination leads to a significant surface to bulk core level shift for the Ni 2p X-ray photoemission core level, not seen in the corresponding Fe 2p core level spectra. Inverse photoemission spectroscopy (IPES), thus provides some indication of the density of states resulting from the dmit2 = 1,3-dithiol-2-thione-4,5-dithiolato ligand unoccupied molecular orbitals.

cond-mat.mtrl-sci↗

arXiv2021

The World in a Grain of Sand: Condensing the String Vacuum Degeneracy

We propose a novel approach toward the vacuum degeneracy problem of the string landscape, by finding an efficient measure of similarity amongst compactification scenarios. Using a class of some one million Calabi-Yau manifolds as concrete examples, the paradigm of few-shot machine-learning and Siamese Neural Networks represents them as points in R(3) where the similarity score between two manifolds is the Euclidean distance between their R(3) representatives. Using these methods, we can compress the search space for exceedingly rare manifolds to within one percent of the original data by training on only a few hundred data points. We also demonstrate how these methods may be applied to characterize `typicality' for vacuum representatives.

hep-th↗

arXiv2020

Machine Learning Etudes in Conformal Field Theories

We demonstrate that various aspects of Conformal Field Theory are amenable to machine learning. Relatively modest feed-forward neural networks are able to distinguish between scale and conformal invariance of a three-point function and identify a crossing-symmetric four-point function to nearly a hundred percent accuracy. Furthermore, neural networks are also able to identify conformal blocks appearing in a putative CFT four-point function and predict the values of the corresponding OPE coefficients. Neural networks also successfully classify primary operators by their quantum numbers under discrete symmetries in the CFT from examining OPE data. We also demonstrate that neural networks are able to learn the available OPE data for scalar correlation function in the 3d Ising model and predict the twists of higher-spin operators that appear in scalar OPE channels by regression.

hep-th↗

arXiv2019

Bounds on Slow Roll at the Boundary of the Landscape

We present strong evidence that the tree level slow roll bounds of arXiv:1807.05193 and arXiv:1810.05506 are valid, even when the tachyon has overlap with the volume of the cycle wrapped by the orientifold. This extends our previous results in the volume-dilaton subspace to a semi-universal modulus. Emboldened by this and other observations, we investigate what it means to have a bound on (generalized) slow roll in a multi-field landscape. We argue that for $any$ point $ϕ_0$ in an $N$-dimensional field space with $V(ϕ_0) > 0$, there exists a path of monotonically decreasing potential energy to a point $ϕ_1$ within a path length $\lesssim {\cal O}(1)$, such that $\sqrt{N}\ln \frac{V(ϕ_1)}{V(ϕ_0)} \lesssim - {\cal O} (1)$. The previous de Sitter swampland bounds are specific ways to realize this stringent non-local constraint on field space, but we show that it also incorporates (for example) the scenario where both slow roll parameters are intermediate-valued and the Universe undergoes a small number of e-folds, as in the Type IIA set up of arXiv:1310.8300. Our observations are in the context of tree level constructions, so we take the conservative viewpoint that it is a characterization of the classical "boundary" of the string landscape. To emphasize this, we argue that these bounds can be viewed as a type of Dine-Seiberg statement.

hep-th↗