Emergence of electric polarity in BiTeX (X = Br and I) monolayers and the giant Rashba spin splitting

Abstract

A number of graphene-like materials have been theoretically predicted and experimentally confirmed so far. Here, based on the first-principles calculations, we predict that stable BiTeX (X = Br and I) monolayers possess intrinsic large polar electric fields along the normal direction to the plane, making them two-dimensional polar systems. Moreover, we find that these novel monolayers with thicknesses of only 3.8 Å can produce a giant Rashba spin splitting derived from their peculiarly polar atomic configurations. Furthermore, the Rashba parameters of BiTeX monolayers can be effectively modulated by applying strain, and are thus promising for wide applications in nanoelectronics.

Structural, vibrational, and electrical study of compressed BiTeBr

“…In fact, the total experimental c/a change at low pressures is less than 0.1 in BiTeBr and around 0.2 in BiTeI [14]. This result is in agreement with the larger polarity of BiTeBr as compared to BiTeI [26], because it can be considered that the stronger the interlayer force the smaller the c/a ratio change.…”

“…[28] could be that of a laser-damaged sample or be the spectrum of a nonpure or oxidized sample. Note that bismuth tellurohalides are polar semiconductors [26] that are very easy to burn during RS measurements for laser powers above 5 mW and very prone to suffer surface oxidation at ambient conditions. In summary, XRD and RS measurements have allowed us to determine the structural parameters and vibrational modes of BiTeBr, thus confirming the BiTeI-type (SG P 3m1) structure of our samples at room conditions.…”

“…Furthermore, recent calculations show that BiTeBr has very interesting properties that feature a larger Rashba spin splitting and larger band gap than BiTeCl and a larger splitting off from the bulk conduction band with more isotropic energy dispersion within the band gap region than BiTeI [22]. Additionally, BiTeBr monolayers have been predicted to exhibit a stronger polar electric field than BiTeI, which is interesting for many applications [26].…”

Potential 2D thermoelectric materialATeI (A= Sb and Bi) monolayers from a first-principles study

“…Recently, based on the first-principles calculations, stable ATeI (A=Sb and Bi) monolayers have been predicted with a giant Rashba spin splitting 25,26 . The thermoelectric properties related with bulk BiTeI have been performed 27 , and the figure of merit ZT at 300 K is 0.05, and the ZT of undoped BiTeI reaches 0.3 at 520 K. The thermoelectric performance of bulk BiTeI can be improved in Cu-intercalated BiTeI 28 or through Brsubstitution 29 .…”

Optical, electronic, and elastic properties of some A5B6C7ferroelectrics (A=Sb, Bi; B=S, Se; C=I, Br, Cl): First principle calculation

“…Kulbachinskiiet et al [19] investigated the thermoelectric and galvanomagnetic properties using the Bridgman method. Ma et al [20] examined the energetic stability electronic and phonon properties of BiTeX (X D Br, I) monolayers using ab initio calculations. Zhu et al [21] calculated the electronic band structure of BiTeCl in the absence of spin orbit coupling using the WIEN2k package.…”