Ferromagnetic (FM) semiconductors have been recognized as the cornerstone for next-generation highly functional spintronic devices. However, the development in practical applications of FM semiconductors is limited by their low Curie temperatures (T _C). Here, on the basis of model analysis, we find that the FM super-exchange couplings in the d ⁵ − d ³ system can be significantly strengthened by reducing the virtual exchange gap (G _ex) between occupied and empty e _g orbitals. By first-principle calculations, we predict robust ferromagnetism in three rhombohedral RMnO₃ (R = Sc, Y, and Lu) compounds with the T _C that is as high as ∼1510K (YMnO₃). The oxygen breathing motions open a band gap and create an unusual Mn²⁺/Mn⁴⁺ charge ordering of the Mn-d electrons, which play an important role in altering the G _ex. Interestingly, the rhombohedral RMnO₃ compounds are also ferroelectric (FE) with a large spontaneous polarization approaching that of LiNbO₃. These results not only deepen the understandings of magnetic couplings in d ⁵ − d ³ system, but also provide a way to design room-temperature FM–FE multiferroics.

铁磁 (FM) 半导体已被公认为下一代高性能自旋电子器件的基石。然而，在FM半导体的实际应用的发展是由它们的低的居里温度（限于Ť _Ç）。在这里，在模型分析的基础上，我们发现d ⁵ - d ³系统中的 FM 超交换耦合可以通过减少占据和空e _g轨道之间的虚拟交换间隙（G _ex）得到显着加强。通过第一性原理计算，我们预测了三个菱面体R MnO ₃ ( R = Sc、Y 和 Lu) 化合物，其T _C高达 ~1510K (YMnO ₃ )。氧气呼吸运动打开带隙并产生不寻常的 Mn ²⁺ /Mn ⁴⁺电荷顺序的 Mn- d电子，这在改变G _{ex 中}起着重要作用。有趣的是，菱形R MnO ₃化合物也是铁电体(FE)，具有接近LiNbO ₃的大自发极化。这些结果不仅加深了对d ⁵ − d ³中磁耦合的理解 系统，但也提供了一种设计室温 FM-FE 多铁性的方法。