We report the existence of bulk persistent spin texture in P4mm tetragonal BiFeO₃, a ferroelectric with ultrahigh spontaneous polarization. Our density functional theory calculations reveal that tetragonal BiFeO₃ exhibits sufficiently strong spin–orbit coupling, yielding a sizable Rashba coefficient of 0.31eV . More importantly, it is demonstrated that the polarization-induced spin–orbit field is unidirectional on the Z–Γ–X plane which contains the polar axis. Consequently, there emerges a momentum-independent spin texture, allowing a long-lived persistent spin helix with a wavelength of 23nm in the real space.

中文翻译：

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四方 BiFeO _{3 中的}持久自旋织构

我们报告了在P 4 mm四方 BiFeO _{3 中}存在大量持久自旋结构，这是一种具有超高自发极化的铁电体。我们的密度泛函理论计算表明，四方 BiFeO ₃表现出足够强的自旋轨道耦合，产生 0.31eV 的相当大的 Rashba 系数。更重要的是，证明了极化诱导的自旋轨道场在包含极轴的Z- Γ- X平面上是单向的。因此，出现了与动量无关的自旋纹理，允许在真实空间中存在波长为 23nm 的长寿命持久自旋螺旋。