Study of the operation temperature in the spin-exchange relaxation free magnetometer

We study the influence of the cell temperature on the sensitivity of the spin-exchange relaxation free (SERF) magnetometer and analyze the possibility of operating at a low temperature. Utilizing a 25 × 25 × 25 mm³ Cs vapor cell with a heating temperature of 85°C, which is almost half of the value of potassium, we obtain a linewidth of 1.37 Hz and achieve a magnetic field sensitivity of 55 fT/Hz^1/2 in a single channel. Theoretical analysis shows that fundamental sensitivity limits of this device with an active volume of 1 cm³ could approach 1 fT/Hz^1/2. Taking advantage of the higher saturated vapor pressure, SERF magnetometer based on Cs opens up the possibility for low cost and portable sensors and is particularly appropriate for lower temperature applications.