Wide range linear magnetometer based on a sub-microsized K vapor cell

TL;DR

This paper introduces a wide-range linear magnetometer utilizing a sub-microsized potassium vapor cell, capable of measuring magnetic fields from 0.1 to 10 kG with micrometer spatial resolution, suitable for high-gradient magnetic field applications.

Contribution

The work demonstrates a novel magnetometry method based on $^{39}$K atoms in a sub-microsized vapor cell, achieving high spatial resolution and broad magnetic field range measurement.

Findings

Able to measure magnetic fields from 0.1 to 10 kG.

Achieves micrometer spatial resolution for magnetic field mapping.

Theoretical model aligns well with experimental data.

Abstract

$^{39}$K atoms have the smallest ground state ($^2S_{1/2}$) hyperfine splitting of all the most naturally abundent alkali isotopes and, consequently, the smallest characteristic magnetic field value $B_0 = A_{^2S_{1/2}}/\mu_B \approx 170$ G, where $A_{^2S_{1/2}}$ is the ground state's magnetic dipole interaction constant. In the hyperfine Paschen-Back regime ($B \gg B_0$, where $B$ is the magnitude of the external magnetic field applied on the atoms), only 8 Zeeman transitions are visible in the absorption spectrum of the $D_1$ line of $^{39}$K, while the probabilities of the remaining 16 Zeeman transitions tend to zero. In the case of $^{39}$K, this behavior is reached already at relatively low magnetic field $B > B_0$. For each circular polarization ($\sigma^-,\sigma^+$), 4 spectrally resolved atomic transitions having a sub-Doppler width are recorded using a sub-microsized vapor cell of thickness $L = 120 - 390$ nm. We present a method that allows to measure the magnetic field in the range $0.1 - 10$ kG with micrometer spatial resolution, which is relevant in particular for the determination of magnetic fields with a large gradient (up to 3 G$/\mu$m). The theoretical model describes well the experimental results.