The atomic-scale structure of hafnium oxide explains ferroelectric properties for very thin films. Switching to the atomic scale Ferroelectric materials are attractive because they provide a way to change electrical resistance by using an electric field. Lee et al. used simulations to explain the persistence of ferroelectric behavior in very thin films of hafnium oxide (see the Perspective by Noheda and Íñiguez). The authors' calculations show that ferroelectric properties should be found in films below 1 nanometer thick. This makes the material very attractive for the next generation of random access memory. Science, this issue p. 1343; see also p. 1300 Discovery of robust yet reversibly switchable electric dipoles at reduced dimensions is critical to the advancement of nanoelectronics devices. Energy bands flat in momentum space generate robust localized states that are activated independently of each other. We determined that flat bands exist and induce robust yet independently switchable dipoles that exhibit a distinct ferroelectricity in hafnium dioxide (HfO2). Flat polar phonon bands in HfO2 cause extreme localization of electric dipoles within its irreducible half-unit cell widths (~3 angstroms). Contrary to conventional ferroelectrics with spread dipoles, those intrinsically localized dipoles are stable against extrinsic effects such as domain walls, surface exposure, and even miniaturization down to the angstrom scale. Moreover, the subnanometer-scale dipoles are individually switchable without creating any domain-wall energy cost. This offers unexpected opportunities for ultimately dense unit cell–by–unit cell ferroelectric switching devices that are directly integrable into silicon technology.

中文翻译：

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HfO2 中平坦声子带诱导的无标度铁电性

氧化铪的原子级结构解释了非常薄的薄膜的铁电特性。切换到原子级铁电材料很有吸引力，因为它们提供了一种通过使用电场来改变电阻的方法。李等人。使用模拟来解释非常薄的氧化铪薄膜中铁电行为的持久性（参见 Noheda 和 Íñiguez 的观点）。作者的计算表明，铁电特性应该存在于厚度低于 1 纳米的薄膜中。这使得该材料对下一代随机存取存储器非常有吸引力。科学，这个问题 p。第1343章 另见第 1300 发现尺寸减小的坚固且可逆的电偶极子对于纳米电子器件的进步至关重要。在动量空间中平坦的能带产生强大的局部状态，这些状态彼此独立激活。我们确定存在平坦带并诱导稳健但可独立切换的偶极子，这些偶极子在二氧化铪 (HfO2) 中表现出明显的铁电性。HfO2 中的扁平极性声子带导致电偶极子在其不可缩减的半晶胞宽度（~3 埃）内极端定位。与具有扩展偶极子的传统铁电体相反，那些固有的局部偶极子对诸如畴壁、表面暴露甚至小到埃级的小型化等外在效应是稳定的。此外，亚纳米级偶极子可单独切换，而不会产生任何畴壁能量成本。