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arXiv 2302.06384cond-mat.str-elcond-mat.mtrl-sci
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静态外部电场下的莫特绝缘体Ca2RuO4

Mott-Insulator Ca2RuO4 under a static external electric field

Giuseppe Cuono, Carmine Autieri

摘要:

我们研究了莫特绝缘体Ca 2 RuO 4的结构,电子和磁性的应用程序下的静态外部电场在两个制度:在小场和大电场薄膜系统。Ca_2RuO_4呈现出S-和L-Pbca相,分别具有短和长的c晶格常数和大和小的带隙。用密度泛函微扰理论计算了玻恩有效电荷的响应函数。一旦我们通过偏离Ru原子的中心来打破反转对称性,我们计算了系统的压电性质,该系统表明在电场下系统的伸长。最后,我们研究了四个单胞平板在较大电场下的情况,发现了由电场引起的绝缘体-金属相变。通过观察局域态密度,我们发现,当样品的其余部分是绝缘的时,表面层上的能隙会闭合。与电场驱动的能隙闭合相关,晶格常数c增加。关于磁性,我们已经确定了两个相变的磁矩与一个表面,得到完全退磁在最大的领域调查。在所有情况下,静态电场增加的晶格常数c和降低的带隙的Ca 2 RuO 4之间的L-相和S-相的竞争中发挥作用。

英文摘要:

We have investigated the structural, electronic and magnetic properties of the Mott-insulator Ca2RuO4 under the application of a static external electric field in two regimes: bulk systems at small fields and thin films at large electric fields. Ca2RuO4 presents an S- and L-Pbca phase with short and long c lattice constants and with large and small band gaps, respectively. Using density functional perturbation theory, we have calculated the Born effective charges as response functions. Once we break the inversion symmetry by off-centering the Ru atoms, we calculate the piezoelectric properties of the system that suggest an elongation of the system under an electric field. Finally, we investigated a four unit cells slab at larger electric fields and we found insulator-metal transitions induced by the electric field. By looking at the local density of states, we have found that the gap gets closed on surface layers while the rest of the sample is insulating. Correlated to the electric-filed-driven gap closure, there is an increase in the lattice constant c. Regarding the magnetic properties, we have identified two phase transitions in the magnetic moments with one surface that gets completely demagnetized at the largest field investigated. In all cases, the static electric field increases the lattice constant c and reduces the band gap of Ca2RuO4 playing a role in the competition between the L-phase and the S-phase.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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