arXiv subjects

Liam Schmidt

Publications and source records attributed to Liam Schmidt.

3 recordsLinked to original sources

arXiv2026

Conductivity scaling of the anomalous Hall effect in the altermagnetic semiconductor {\alpha}-MnTe

{\alpha}-MnTe is a prototypical altermagnet exhibiting a strong anomalous Hall effect (AHE), despite having a nearly vanishing magnetization. Lately, sample-to-sample variations of the amplitude of the AHE have raised concerns of a possible defect related origin, especially in thin films. Here, we study the AHE in {\alpha}-MnTe films grown on SrF2 that have the crystal structure and m'm'm magnetic point group symmetry expected for bulk. By studying the scaling of the AHE with conductivity for those films and previously reported measurements in the literature, we find that sample-to-sample variations are well explained by a scaling law consistent with a hopping origin. Importantly, a comparison with other magnetic semiconductors reveals the colossal amplitude of the AHE of {\alpha}-MnTe compared to its measured spontaneous magnetization from magnetometry and polarized neutron reflectivity. Our findings address the important fundamental question of the origin of the AHE of {\alpha}-MnTe and further demonstrate the potential of altermagnets as promising spintronic materials.

cond-mat.str-el↗

arXiv2025

Coincidence Algebra Bundle for Decay Quivers: An Algebraic Approach to Gamma-ray Spectroscopy

Motivated by the need for a more comprehensive algebraic structure to calculate coincidence probabilities of a general decay scheme for gamma ray spectroscopy, we model the decay scheme, rather naturally, as a quiver through which we define a decay quiver. The path algebra of quivers is the underlying, more general, algebra for transition matrices that is typically used in modeling decay schemes. The path algebra allows for concatenation of transitions which affords the calculation of cascade probabilities. We extend the path algebra to allow for the multiplication of non-composable paths, i.e., transition that don't directly share a level connecting them. We define the coincidence algebra as the algebra that allows for such an extension and realize it as the fibres for a coincidence algebra bundle, the base space of which is the path algebra where decay schemes live. A given decay schemes coincidence probabilities are calculated on its fibre. \textit{Detection maps} are defined as maps on the base space that map transition probabilities to detected probabilities.

physics.data-an↗

arXiv2025

On the Measurability of True Coincidence Summing in the GRIFFIN Spectrometer

The measurement of gamma-rays from decaying nuclei allow for the investigation into nuclear structure. True coincidence summing occurs when two gamma-rays from a single decay get detected in a single detector and their energies sum together to give false peaks in the energy spectrum. Corrections to this summing effect are crucial for an accurate determination of nuclear decay events. The summing correction formalism of Semkow et al. is generalized here into the \textit{Semkow matrix formalism} and is extended into a multiplicity expansion. This formalism is used to calculate the matrix probabilities for 180-degree coincidence events as a method for correcting coincidence summing; in doing so, the deviation between the full correction and this 180-degree correction is shown as a function of multiplicity. This formalism is extended to the \textit{partitioned matrix formalism}, to calculate probabilities for \textit{gated} gamma rays; where two gamma-rays of interest are taken in multi-detector coincidence. The summing correction probabilities for gated gamma-rays are provided and the deviation is shown in a manner similar to that of the singles. Terms such as measurability, event equivalence, and ontic and epistemic events are defined. It is shown that within these definitions, coincidence summing is not sufficiently measurable, or rather, its sufficient measurability is statistically bounded by the deviations derived.

physics.ins-det↗