Solutions to axion electrodynamics in various geometries

Recently there has been a surge of new experimental proposals to search for ultralight axion dark matter with axion mass, m_{a}≲1  μeV. Many of these proposals search for small oscillating magnetic fields induced in or around a large static magnetic field. Lately, there has been interest in alternate detection schemes which search for oscillating electric fields in a similar setup. In this paper, we explicitly solve Maxwell’s equations in a simplified geometry and demonstrate that in this mass range, the axion-induced electric fields are heavily suppressed by boundary conditions. Unfortunately, experimentally measuring axion-induced electric fields is not feasible in this mass regime using the currently proposed setups with static primary fields. We show that at larger axion masses, induced electric fields are not suppressed, but boundary effects may still be relevant for an experiment’s sensitivity. We then make a general argument about a generic detector configuration with a static magnetic field to show that the electric fields are always suppressed in the limit of large wavelength.National Science Foundation (U.S.) (Award No. 1806440

Design and Implementation of the ABRACADABRA-10 cm Axion Dark Matter Search

The past few years have seen a renewed interest in the search for light particle dark matter. ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, $10^{-12}\lesssim m_a\lesssim10^{-6}$ eV. ABRACADABRA-10 cm is a small-scale prototype for a future detector that could be sensitive to QCD axion couplings. In this paper, we present the details of the design, construction, and data analysis for the first axion dark matter search with the ABRACADABRA-10 cm detector. We include a detailed discussion of the statistical techniques used to extract the limit from the first result with an emphasis on creating a robust statistical footing for interpreting those limits.Comment: 12 pages, 8 figure

Intrinsic Electron Mobility Exceeding 10³ cm²/(V s) in Multilayer InSe FETs

Graphene-like two-dimensional (2D) materials not only are interesting for their exotic electronic structure and fundamental electronic transport or optical properties but also hold promises for device miniaturization down to atomic thickness. As one material belonging to this category, InSe, a III–VI semiconductor, not only is a promising candidate for optoelectronic devices but also has potential for ultrathin field effect transistor (FET) with high mobility transport. In this work, various substrates such as PMMA, bare silicon oxide, passivated silicon oxide, and silicon nitride were used to fabricate multilayer InSe FET devices. Through back gating and Hall measurement in four-probe configuration, the device’s field effect mobility and intrinsic Hall mobility were extracted at various temperatures to study the material’s intrinsic transport behavior and the effect of dielectric substrate. The sample’s field effect and Hall mobilities over the range of 20–300 K fall in the range of 0.1–2.0 × 10³ cm²/(V s), which are comparable or better than the state of the art FETs made of widely studied 2D transition metal dichalcogenides

First Results from ABRACADABRA-10 cm: A Search for Sub-μeV Axion Dark Matter

The axion is a promising dark matter candidate, which was originally proposed to solve the strong-CP problem in particle physics. To date, the available parameter space for axion and axionlike particle dark matter is relatively unexplored, particularly at masses m_{a}≲1  μeV. ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, 10^{-12}≲m_{a}≲10^{-6}  eV. ABRACADABRA-10 cm is a small-scale prototype for a future detector that could be sensitive to the QCD axion. In this Letter, we present the first results from a 1 month search for axions with ABRACADABRA-10 cm. We find no evidence for axionlike cosmic dark matter and set 95% C.L. upper limits on the axion-photon coupling between g_{aγγ}<1.4×10^{-10} and g_{aγγ}<3.3×10^{-9}  GeV^{-1} over the mass range 3.1×10^{-10}–8.3×10^{-9}  eV. These results are competitive with the most stringent astrophysical constraints in this mass range