Ground state and magnetic phase transitions of orthoferrite DyFeO_3

TL;DR

This study investigates the low-temperature magnetic, electric, and thermal properties of DyFeO_3 single crystals, revealing complex phase transitions and a previously unknown ground state in the material.

Contribution

It uncovers a complex low-temperature phase diagram and identifies a novel ground state in DyFeO_3, expanding understanding of multiferroic orthoferrites.

Findings

Multiple magnetic phase transitions at low temperatures and fields.

Irreversible magnetic, electric, and thermal responses indicating complex phase behavior.

Discovery of an unexplored ground state below 500 mK.

Abstract

Low-temperature thermal conductivity (\kappa), as well as magnetization (M) and electric polarization (P), of multiferroic orthoferrite DyFeO_3 single crystals are studied with H \parallel c. When the crystal is cooled in zero field, M, P, and \kappa all consistently exhibit irreversible magnetic-field dependencies. In particular, with 500 mK < T \le 2 K, all these properties show two transitions at the first run of increasing field but only the higher-field transition is present in the subsequent field sweepings. Moreover, the ultra-low-T (T < 500 mK) \kappa(H) shows a different irreversibility and there is only one transition when the field is swept both up and down. All the results indicate a complex low-T H-T phase diagram involving successive magnetic phase transitions of the Fe^{3+} spins. In particular, the ground state, obtained with cooling to subKelvin temperatures in zero field, is found to be an unexplored phase.