Magnetic transitions and magnetodielectric effect in the antiferromagnet SrNdFeO$_4$

TL;DR

This study explores the magnetic phase transitions and magnetodielectric coupling in SrNdFeO$_4$, revealing complex spin reorientations and their influence on dielectric properties, with implications for multiferroic materials.

Contribution

It provides the first detailed magnetic phase diagram of SrNdFeO$_4$ and links magnetic transitions to dielectric anomalies, highlighting spin-lattice coupling in this compound.

Findings

Fe$^{3+}$ spins order antiferromagnetically below 360 K

Spin reorientation occurs around 35-37 K from ab-plane to c-axis

Dielectric permittivity anomalies coincide with magnetic transitions

Abstract

We investigated the magnetic phase diagram of single crystals of SrNdFeO$_{4}$ by measuring the magnetic properties, the specific heat and the dielectric permittivity. The system has two magnetically active ions, Fe$^{3+}$ and Nd$^{3+}$. The Fe$^{3+}$ spins are antiferromagnetically ordered below 360 K with the moments lying in the ab-plane, and undergo a reorientation transition at about 35-37 K to an antiferromagnetic order with the moments along the c-axis. A short-range, antiferromagnetic ordering of Nd$^{3+}$ along the c-axis was attributed to the reorientation of Fe$^{3+}$ followed by a long-range ordering at lower temperature [S. Oyama {\it et al.} J. Phys.: Condens. Matter. {\bf 16}, 1823 (2004)]. At low temperatures and magnetic fields above 8 T, the Nd$^{3+}$ moments are completely spin-polarized. The dielectric permittivity also shows anomalies associated with spin configuration changes, indicating that this compound has considerable coupling between spin and lattice. A possible magnetic structure is proposed to explain the results.