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

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 Nèel domain walls. We find positive room-temperature magneto-capacitance up to 9T, linear at low-fields (MC ~ Hlow); the prefactor slope (dlnε'/dHlow) featuring a positive frequency-coefficient rises from O(10-3/T) at 0.1MHz to O(10-1/T) at 4MHz, with maximum dε'/dH ~ 120/T.