Fig. 4: Corner states of ML Nb3TeCl7. | npj Quantum Materials

Fig. 4: Corner states of ML Nb3TeCl7.

From: Orbital degree of freedom induced multiple sets of second-order topological states in two-dimensional breathing Kagome crystals

Fig. 4

a Energy spectrum of the triangular nanodisk of Configuration 1 (\(L = 8\)) of ML Nb3TeCl7. Energy levels are plotted in ascending order. Two sets of corner states are indicated by blue solid circles. The inset: enlarged drawing of CS-I and CS-II. The three corner states of CS-I are labeled as \(\varphi _1\), \(\varphi _2\) and \(\varphi _3\), respectively. b, c The calculated local density of states of CS-I and CS-II, respectively. The three equivalent mirrors Mx are indicated by red dashed lines. d Schematic drawing of crystal field splitting of Nb 4d orbitals in NbTeCl5 octahedron. The inset shows the NbTeCl5 octahedron. The angle between rotated (Nb-Te direction) and previous (out of plane direction) z-direction is \(\beta\). e The solid (dotted) line shows the energy splitting \({\Delta}{{{\mathrm{E}}}}_{{{{\mathrm{split}}}}}\) (absolute value of \({\Delta}{{{\mathrm{E}}}}_{{{{\mathrm{split}}}}}\)) as a function of nanodisk size \(L\). The inset shows the effective model to interpret the finite-size effect. The inter-corner effective hopping is \(t\).

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