Giant magnetostriction and nonsaturating electric polarization up to 60 T in the polar magnet CaBaCo4O7

TL;DR

This study demonstrates giant magnetostriction and a record-breaking magnetoelectric effect in the insulating oxide CaBaCo4O7, revealing new pathways to enhance multifunctional properties in transition metal oxides.

Contribution

It reports the first observation of giant magnetostriction (>1500 ppm) coupled with a large magnetoelectric response in an insulating transition metal oxide.

Findings

Giant magnetostriction (>1500 ppm) observed in CaBaCo4O7.

Record-breaking change in electric polarization (~1.6 μC/cm²) under magnetic field.

Giant magnetostriction linked to geometric frustration and orbital instability.

Abstract

Giant magnetostriction in insulating magnetic materials is highly required for applications but is rarely observed. Here we show that giant magnetostriction (> 1500 ppm) can be achieved in an insulating transition metal oxide CaBaCo4O7 where the ferrimagnetic ordering at TC ~ 62 K is associated with a huge change in the lattice. Moreover, because this material is pyroelectric with a non-switchable electric polarization (P), the giant magnetostriction results in a record-breaking magnetoelectric effect - a gigantic change of electric polarization (deltaP ~ 1.6 {\mu}C/cm2) in response to the applied magnetic field up to 60 T. Geometric frustration as well as the orbital instability of Co2+/Co3+ ions is believed to play a crucial role in the giant magnetostriction. Our study provides new insights on how to achieve both giant magnetostriction and pronounced magnetoelectric effect in insulating transition metal oxides.