Multiferroicity in Li0.05Ti0.02Ni0.93O Above Room Temperature

TL;DR

This study provides direct evidence of multiferroic behavior above room temperature in Li0.05Ti0.02Ni0.93O, showing coupled magnetic and electric properties with potential applications in high-temperature devices.

Contribution

It demonstrates above-room-temperature multiferroicity in a single-phase material with detailed analysis of its magnetic, electric, and magneto-capacitive properties.

Findings

Magneto-electric coupling observed above 488K

Large polarization at room temperature

Positive magneto-capacitance up to 9T

Abstract

We present direct evidence of above room temperature magneto-electricity in single-phase Li0.05Ti0.02Ni0.93O with above-ambient antiferromagnetic ordering. Temperature-hysteresis in warming/cooling heat-flow thermograms establishes a discontinuous/first-order nature of the cubic-to-rhombohedral structural change concurring the AFM transition. At TN = 488K, magnetization features a sharp slope-&-curvature discontinuity and dielectric constant shows a peak-anomaly. Room temperature P-E loop measures a large polarization traceable to the N\`eel domain walls. We find positive room-temperature magneto-capacitance up to 9T, linear at low-fields (MC ~ Hlow); the prefactor slope (dln{\epsilon}'/dHlow) featuring a positive frequency-coefficient rises from O(10-3/T) at 0.1MHz to O(10-1/T) at 4MHz, with maximum d{\epsilon}'/dH ~ 120/T.