I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, D-20355 Hamburg, Germany.
Code 6393, Naval Research Laboratory, Washington, DC 20375, USA.
Phys Rev Lett. 2018 Sep 7;121(10):106401. doi: 10.1103/PhysRevLett.121.106401.
While the phase diagrams of the one- and multiorbital Hubbard model have been well studied, the physics of real Mott insulators is often much richer, material dependent, and poorly understood. In the prototype Mott insulator V_{2}O_{3}, chemical pressure was initially believed to explain why the paramagnetic-metal to antiferromagnetic-insulator transition temperature is lowered by Ti doping while Cr doping strengthens correlations, eventually rendering the high-temperature phase paramagnetic insulating. However, this scenario has been recently shown both experimentally and theoretically to be untenable. Based on full structural optimization, we demonstrate via the charge self-consistent combination of density functional theory and dynamical mean-field theory that changes in the V_{2}O_{3} phase diagram are driven by defect-induced local symmetry breakings resulting from dramatically different couplings of Cr and Ti dopants to the host system. This finding emphasizes the high sensitivity of the Mott metal-insulator transition to the local environment and the importance of accurately accounting for the one-electron Hamiltonian, since correlations crucially respond to it.
虽然单轨道和多轨道 Hubbard 模型的相图已经得到了很好的研究，但实际的莫特绝缘体的物理性质通常更加丰富、依赖于材料且理解不足。在原型莫特绝缘体 V_{2}O_{3}中，化学压力最初被认为可以解释为什么 Ti 掺杂会降低顺磁金属到反铁磁绝缘的转变温度，而 Cr 掺杂则增强了相关性，最终使高温相呈现顺磁绝缘。然而，最近的实验和理论研究都表明，这种情况是站不住脚的。基于完全的结构优化，我们通过密度泛函理论和动态平均场理论的电荷自洽组合证明，V_{2}O_{3}相图的变化是由 Cr 和 Ti 掺杂剂与宿主系统的耦合显著不同导致的缺陷诱导的局部对称破坏所驱动的。这一发现强调了莫特金属-绝缘转变对局部环境的高度敏感性，以及准确考虑单电子哈密顿量的重要性，因为相关性对此至关重要。
