Non-trivial quantum magnetotransport oscillations in pure and robust topological $α$-Sn films

Elemental Topological Dirac Semimetal α‐Sn with High Quantum Mobility

“…In situ reflection high-energy electron diffraction along the [110] axis showed streaky patterns (Figure S1b,c, Supporting Information), indicating a 2D growth mode of both α-Sn with a diamond-type crystal structure and InSb with a zinc-blende-type crystal structure throughout the MBE growth. An In-stabilized InSb topmost surface that showed c(8 × 2) reconstruction was prepared, which is similar to previous works in which α-Sn was grown directly on an InSb substrate [27][28][29]32,33,35,37] (see Figure S1b, Supporting Information and comparison with previous works in Notes S1,S2, Supporting Information). The cross-sectional STEM lattice image (Figure 1c) clearly indicated a high-quality epitaxial α-Sn thin film of a diamondtype crystal structure with no visible defects and an atomically flat α-Sn/InSb interface.…”

“…The quantum mobility of the TSS is experimentally estimated for the first time and is one order of magnitude higher than the mobility (≈3000 cm 2 V −1 s −1 ) estimated by the Hall measurements (namely, Hall mobility) reported in all previous works. [30,33,34] The results described above have been achieved because of the high crystal quality and atomically flat interface of our α-Sn/InSb heterostructure (note that for the same sample, the quantum mobility is usually much smaller than the Hall mobility). Meanwhile, the F 3 component with a relatively heavy cyclotron mass (m 3 = 0.11 m 0 ) can be attributed to the HH band of α-Sn because there are no other carriers in α-Sn and InSb that have such a heavy cyclotron mass.…”

“…In previous studies, α-Sn was grown directly on an ion-milled InSb substrate surface, which deteriorates the interface and bulk quality. [27][28][29]32,33,35,37] In another work, Bi or Te was deposited as a surfactant during α-Sn growth, which unwantedly voided the advantage of the elemental topological material α-Sn. [27][28][29]37] High-quality and well-controlled α-Sn is thus urgently required to realize its full potential.…”

“…[23][24][25][26] However, TDS materials have rarely been realized thus far; [11] the only experimentally identified cases are Na 3 Bi [4,20,21] and Cd 3 As 2 , [5,12,13,[17][18][19] except for one report on α-Sn (111). [14] Among many topological materials, α-Sn [27][28][29][30][31][32][33][34][35] stands out as a unique and promising candidate: It is the only elemental material that shows multiple topological phases, which can be controlled by various means such as applying strain, varying the thickness, incorporating magnetism, and applying electric α-Sn provides an ideal avenue to investigate novel topological properties owing to its rich diagram of topological phases and simple elemental material structure. Thus far, however, the realization of high-quality α-Sn remains a challenge, which limits the understanding of its quantum transport properties and device applications.…”

“…However, thus far, very few studies have accurately captured the nontrivial features of α-Sn, especially its quantum transport properties. [29,[31][32][33][34] The main reason for this lack of study is the insufficient crystal quality because α-Sn can easily transform Γ + bands (iLH and HH) and an s-derived (red) 7 Γ − band. The origin of the vertical axis corresponds to the Fermi energy of the calculation.…”