Magnetoelectric coupling in Haldane spin chain system, Dy2BaNiO5

TL;DR

This study demonstrates strong magnetoelectric coupling and magnetism-induced ferroelectricity in Dy2BaNiO5, a Haldane spin chain system, through comprehensive measurements revealing multiple magnetic and dielectric anomalies and transitions.

Contribution

It provides the first evidence of magnetoelectric coupling and multiferroicity in Dy2BaNiO5, a nickel-based Haldane spin chain compound, highlighting its potential as a new multiferroic material.

Findings

Magnetic ordering occurs at 58K.

Dielectric anomalies at 12.5, 30, 50, and 58K.

Electric polarization observed in the magnetically ordered state.

Abstract

We report the results of various measurements, namely magnetization, complex dielectric permittivity and electric polarization (P) on Dy2BaNiO5 as a function of temperature (T) and magnetic-field (H), apart from heat-capacity (C), with the primary motivation of exploring the existence of magnetoelectric (ME) coupling among Haldane spin-chain systems. The M(T) and C(T) data establish long range magnetic ordering at 58K. The most noteworthy observations are: (i) Distinct anomalies are observed in dielectric constant ({\epsilon}') vs T and loss (tan{\delta}) vs T at different temperatures, i.e. 12.5, 30, 50 and 58K; at low temperatures, three magnetic-field-induced transitions are observed in {\epsilon}' vs H at 6, 40 and 60 kOe. These transition temperatures and critical magnetic fields track those obtained from magnetization data. This establishes the existence of strong magnetoelectric coupling in this compound. (ii) Correspondingly, electric polarization could be observed as a function of T and H in the magnetically ordered state, thereby indicating magnetism-induced ferroelectricity in this compound; this result suggests that this compound is a possible new multiferroic material among spin = 1 (nickel containing) compounds with successive magnetic transitions and strong magnetoelectric coupling.