Spin-exchange relaxation of naturally abundant Rb in a K-Rb-²¹Ne self-compensated atomic comagnetometer

The total effective spin-exchange relaxation of naturally abundant Rb in a K-Rb-²¹Ne comagnetometer is analyzed, and the results show that the coexistence of ⁸⁷Rb and ⁸⁵Rb isotopes in the same volume can lead to a large extra spin-exchange broadening compared to pure ⁸⁷Rb. This broadening mainly comes from the contribution of the equivalent reduction in the Rb spin-exchange rate. On this basis, an approximate relaxation model is proposed and experimentally demonstrated to be more accurate than that from a previous work. This study also provides a method for determining the properties of alkali-metal vapor cells.