Coexistence of Ferroelectricity and Ferromagnetism in Fullerene-Based One-Dimensional Chains

One-dimensional (1D) magnetoelectric multiferroics are promising multifunctional materials for miniaturized sensors, actuators, and memories. However, 1D materials with both ferroelectricity and ferromagnetism are quite rare. Herein, using first-principles calculations, a series of fullerene-based 1D chains, namely U₂ C@C₈₀ -M (M = Cr, Mn, Mo, and Ru) 1D chains with both ferroelectric (FE) and ferromagnetic (FM) properties is designed. Compared to individual U₂ C@I_h (7)-C₈₀ , the spontaneous polarization (Ps) in 1D chains is enhanced by about two to four times owing to the interaction between U₂ C@I_h (7)-C₈₀ fullerene and M (M = Cr, Mn, Mo, and Ru) atoms. Meanwhile, the introduction of transition metal atoms dopes electrons into U's 5f orbitals, leading to numerous intriguing magnetic properties, such as U₂ C@C₈₀ -Cr and U₂ C@C₈₀ -Mo as 1D ferromagnetic semiconductors, U₂ C@C₈₀ -Ru as 1D ferrimagnetic (FiM) semiconductor, and U₂ C@C₈₀ -Mn as 1D antiferromagnetic (AFM) semiconductor. Excitingly, it is found that magnetic ordering and electrical polarization can be modulated independently by linking different transition metal atoms. These findings not only broaden the range of 1D multiferroic materials, but also provide promising candidates for novel electronic and spintronic applications.