Magnetic transitions in CsMnCl₃·2H₂O studied by magnetostriction and magnetothermal techniques

Magnetic phase transitions in the orthorhombic antiferromagnet CsMnCl₃·2H₂O (T_N = 4.88 K have been examined by magnetostriction and magnetothermal methods. Dimensional changes along the principal axes were measured as a function of temperature and applied magnetic field up to 100 kOe in the antiferromagnetic, spin-flopped and paramagnetic phases and through the transitions between these states. In the antiferromagnetic phase a power-law field dependence of the linear strains was found, ε ∝ Hⁿ, with the exponent n varying between 2.0 and 2.6, according to temperature and direction of observation. For low fields the volume strain varies approximately quadratically with applied field. At the antiferromagnetic spin-flop transition the linear and volume magnetostrictions show characteristic anomalies which allow precise identification of the critical field. An observed hysteresis of about 1% at this transition is believed to be connected with its first-order character.