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

Abstract

39 K atoms have the smallest ground state ( 2 S 1 / 2 ) hyperfine splitting of all the most naturally abundant alkali isotopes and, consequently, the smallest characteristic magnetic field value B 0 = A 2 S 1 / 2 / μ B ≈ 170 G , where A 2 S 1 / 2 is the ground state’s magnetic dipole interaction constant. In the hyperfine Paschen–Back regime ( B ≫ B 0 , where B is the magnitude of the external magnetic field applied on the atoms), only eight 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 ( σ − , σ + ), four spectrally resolved atomic transitions having sub-Doppler widths are recorded using a sub-microsized vapor cell of thickness L = 120 − 390 n m . We present a method that allows to measure the magnetic field in the range of 0.1 − 10 k G with micrometer spatial resolution, which is relevant in particular for the determination of magnetic fields with large gradients (up to 3 G/µm). The theoretical model describes well the experimental results.