Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
CENN Nanocenter, Jamova 39, SI-1000 Ljubljana, Slovenia.
Phys Rev Lett. 2019 Jan 25;122(3):036802. doi: 10.1103/PhysRevLett.122.036802.
1T-TaS_{2} is a charge-density-wave (CDW) compound with a Mott-insulating ground state. The metallic state obtained by doping, substitution, or pulsed charge injection is characterized by an emergent CDW domain-wall network, while single domain walls can be found in the pristine Mott state. Here we study whether and how the single walls become metallic. Tunneling spectroscopy reveals partial suppression of the Mott gap and the presence of in-gap states strongly localized at the domain-wall sites. Using the real-space dynamical mean field theory description of the strongly correlated quantum-paramagnet ground state, we show that the local gap suppression follows from the increased hopping along the connected zigzag chain of lattice sites forming the domain wall. Furthermore, we show that full metallization is preempted by the splitting of the quasiparticle band into bonding and antibonding subbands due to the structural dimerization of the wall, explaining the presence of the in-gap states and the low density of states at the Fermi level.
1T-TaS_{2} 是一种具有莫特绝缘基态的电荷密度波（CDW）化合物。通过掺杂、取代或脉冲电荷注入获得的金属态的特征是出现 CDW 畴壁网络，而在原始莫特态中可以找到单个畴壁。在这里，我们研究单个壁是否以及如何变成金属态。隧道谱揭示了莫特能隙的部分抑制以及强烈局域在畴壁位置的能隙中的态。使用强关联量子顺磁基态的实空间动态平均场理论描述，我们表明，局部能隙抑制是由于沿形成畴壁的晶格位点的连接之字形链的跳跃增加所致。此外，我们表明，由于壁的结构二聚化，准粒子能带分裂为成键和反键子带，从而阻止了完全金属化，这解释了能隙中的态和费米能级处低态密度的存在。
