An analysis of the mixed state in ${\mathrm{ErRh}}_4$${\mathrm{B}}_4$ is presented and the results are compared with the recent measurements of the magnetic properties of single-crystal ${\mathrm{ErRh}}_4$${\mathrm{B}}_4$. The analysis includes the shielding of the Er magnetic moment by the persistent current, the polarization of the conduction electrons by the Er magnetic moment, and the scattering of the conduction electrons by the spin fluctuations. Good agreement with both the hard- and easy-magnetization-axis measurements is obtained using a single value of ${\kappa }_B$ in both directions. Unlike previous analysis, the formalism employed permits the analysis of the region in which the transition from the mixed state to the normal state is first order. The jump in the magnetization at $H_{c2\mathrm{}}$ is computed as a function of temperature.

• Received 22 November 1983

DOI:https://doi.org/10.1103/PhysRevB.30.1314