Magnetic Excitations in Rb2CrxMn1-xCl4 Mixed Crystals

Solid solutions of Rb2CrCl4 and Rb2MnCl4 are of particular interest since there are not only competing anisotropy energies due to the single ion anisotropy of Cr²⁺ but also competing exchange interactions. We have studied the magnetic excitations of Rb2CrxMn1-xCl4 mixed crystals by means of magnetic resonance in the concentration range 0.02 < x < 0.41 where there is a long range antiferromagnetic order different from that of pure Rb2MnCl4 and in the concentration range 0.41 < x < 0.59 where there is no long range order. Our results in the latter range confirm a spin glass behavior at low temperatures. In the antiferromagnetic range, our results provide information about the exchange interactions and the anisotropy fields.