Mitrofanovite Pt₃Te₄: A Topological Metal with Termination-Dependent Surface Band Structure and Strong Spin Polarization

Abstract

Due to their peculiar quasiparticle excitations, topological metals have high potential for applications in the fields of spintronics, catalysis, and superconductivity. Here, by combining spin-and angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and density functional theory, we discover surface-termination-dependent topological electronic states in the recently discovered mitrofanovite Pt 3 Te 4 . Mitrofanovite crystal is formed by alternating, van der Waals bound layers of Pt 2 Te 2 and PtTe 2 . Our results demonstrate that mitrofanovite is a topological metal with terminationdependent (i) electronic band structure and (ii) spin texture. Despite their distinct electronic character, both surface terminations are characterized by electronic states exhibiting strong spin polarization with a node at the Γ point and sign reversal across the Γ point, indicating their topological nature and the possibility of realizing two distinct electronic configurations (both of them with topological features) on the surface of the same material.

Topological electronic structure of YbMg$_2$Bi$_2$ and CaMg$_2$Bi$_2$

“…On the optically-flat surface regions, we observe different step heights, suggesting different surface terminations. The coexistence of different surface terminations has been observed for various materials such as Pt 3 Te 4 , YBa 2 Cu 4 O 8 and Bi 4 Se 3 using micro/nano ARPES and scanning-tunneling microscopy (STM) [44][45][46]. Similar microscopic studies would be needed to disentangle the contributions from different terminations in the present materials.…”

MBE-grown ultrathin PtTe2 films and their layer-dependent electronic structures

“…At 350 °C, another pair of peaks located at 74.73 and 71.40 eV appears, which matches well with the Pt 4f peak positions of Pt 2+ in PtTe or Pt 2 Te 2 (labeled as Pt 2+ ). 25,36 The Pt 2+ component becomes more pronounced at 400 °C, indicating that high growth temperature causes Te deficiency. In Fig.…”

Efficient Hydrogen Evolution Reaction with Bulk and Nanostructured Mitrofanovite Pt3Te4

“…The Pt-4f 7/2 component was characterized by two components located at binding energies (BEs) of 71.5 and 72.3 eV, respectively ( Figure 2 b). Actually, the presence of these two well-distinct spectral components was due to the PtTe 2 and Pt 2 Te 2 sub-units [ 18 ]. The Te-3d core level was characterized by one doublet shifted by 10.4 eV, with the binding energy of Te-3d 5/2 peak of 573.1 eV ( Figure 2 a).…”

“…In particular, mitrofanovite is a recently discovered mineral [ 17 ], which was demonstrated to be a topological metal with spin-polarized surface states, with subsequent capabilities for applications in spintronics [ 18 ]. Nevertheless, recent findings from different groups highlight the huge potential of mitrofanovite for hydrogen production [ 19 , 20 ].…”