Studies on the origin of the interfacial superconductivity of Sb ₂ Te ₃ /Fe _1+y Te heterostructures

Abstract

The recent discovery of the interfacial superconductivity (SC) of the Bi2Te3/Fe1+yTe heterostructure has attracted extensive studies due to its potential as a novel platform for trapping and controlling Majorana fermions. Here we present studies of another topological insulator (TI)/Fe1+yTe heterostructure, Sb2Te3/Fe1+yTe, which also has an interfacial 2-dimensional SC. The results of transport measurements support that reduction of the excess Fe concentration of the Fe1+yTe layer not only increases the fluctuation of its antiferromagnetic (AFM) order but also enhances the quality of the SC of this heterostructure system. On the other hand, the interfacial SC of this heterostructure was found to have a wider-ranging TI-layer thickness dependence than that of the Bi2Te3/Fe1+yTe heterostructure, which is believed to be attributed to the much higher bulk conductivity of Sb2Te3that enhances indirect coupling between its top and bottom topological surface states (TSSs). Our results provide evidence of the interplay among the AFM order, itinerant carries from the TSSs, and the induced interfacial SC of the TI/Fe1+yTe heterostructure system.

Oxygen Adsorption Induced Superconductivity in Ultrathin FeTe Film on SrTiO3(001)

“…No Fe adatoms (or interstitial Fe atoms) and Te vacancies can be observed on the surface, which indicates nearly stoichiometric FeTe epitaxy films. To carry out electronic transport measurement, the protection Te layer was deposited on the 10UC FeTe surface, and the results were shown in Figure 1 c. No superconducting transition but semiconducting behavior was observed in initially grown 10UC FeTe film down to 1.8 K, consistent with previous experiments [ 25 , 26 ]. Compared with bulk or thick FeTe films [ 11 , 13 , 23 , 27 , 28 , 29 ], we have not found an anomaly in the R - T curve between 40 K and 80 K, which further demonstrates free of Fe interstitial atoms [ 26 ].…”

“…Such oxygen-induced hole doping effect [ 31 ] was recently observed on the CsV 3 Sb 5 with an increased superconducting transition temperature. Additionally, hole doping effects were observed in Bi 2 Te 3 /FeTe [ 32 , 33 ] and Sb 2 Te 3 /FeTe [ 26 ] heterostructures and thought to be the origin of two-dimensional superconductivity in the heterostructures. Figure 4 b shows the d I /d V spectra in a small energy range.…”

Comprehensive review on topological superconducting materials and interfaces

“…These heterostructures were grown by using Molecular Beam Epitaxy (MBE) deposition technique, taking Bi2Se3 as a TI and NbSe2 as a superconductor. Also, proximity induced superconductivity was observed with other heterostructures as Sn-Bi2Se3 [280], Bi2Te3-NbSe2 [281][282][283], Bi2Te3-FeTe0.55Se0.45 [284], Sb2Te3-FeTe [285], Pb-TlBiSe2 [286]. This method became a popular method to achieve topological superconductivity afterward.…”

Two‐Dimensional Metal Telluride Atomic Crystals: Preparation, Physical Properties, and Applications

“…Since stabilized superconductivity can exist in the heterostructures containing the TIs of Sb 2 Te 3 or Bi 2 Te 3 , their interactions may offer a new method for studying Majorana fermions, which are subject to non‐Abelian statistics. [ 160–162 ] Wang et al. [ 161 ] discovered the robust 2D interfacial superconductivity in the Bi 2 Te 3 /FeTe heterostructures with various epilayer thickness of Bi 2 Te 3 .…”

“…Later in 2019, Sou et al. [ 162 ] studied the origin of the interfacial superconductivity in another TIs of Sb 2 Te 3 /Fe 1+ y Te heterostructures. The Sb 2 Te 3 /Fe 1+ y Te heterostructure displays an interfacial 2D superconductivity which has a wider TIs‐layer thickness‐dependent ranging than that of Bi 2 Te 3 /Fe 1+ y Te.…”