Transferred hyperfine interaction for Rb87 and Cs133 in AMnCl3 (A=Rb and Cs) single crystals

Abstract

The transferred hyperfine interactions at the A nuclei in AMnCl3 (A=Rb and Cs) crystals were measured on both sides of their corresponding Néel temperatures, TN. The changes in the curves of the transferred hyperfine field, Hhf, near 94.6 and 67 K for the Rb and the Cs nucleis, respectively, were associated with paramagnetic-to-antiferromagnetic transitions in these crystals. The Hhf due to transfer of the spin density from the Mn2+ ion to the A ion was obtained in the paramagnetic and the antiferromagnetic regions. The change in the Hhf for Rb and Cs nuclei may be due to differences in the contributions of the Mn2+ ions. Also, the temperature dependences of Hhf for Rb and Cs nuclei in RbMnCl3 and CsMnCl3 change abruptly in the antiferromagnetic phase, and the abrupt increase in the Hhf is large enough to allow transfer of the spin density from the Mn2+ ion to the A ion for TN>T. This result is consistent with the increases in the spin-lattice relaxation times, which were observed in previous research, for both crystals.