Inversion of Conduction and Valence Bands inPb1−xSnxSeAlloys

Abstract

Single-crystal films of Pbi^Sn^Se alloys with rocksalt structure (0<#<0.33) have been deposited by evaporation on cleaved (100) faces of KC1 substrates. The energy gap E g at T=300, 195, and 77°K has been determined by measuring the optical transmission between 2 and 25 /xm. As x increases or T decreases, E g decreases for sufficiently low values of x, but increases for #>0.2 and r=77°K. The sign reversal in the composition and temperature dependence of E g shows that the Pbi-xSn^Se alloys exhibit the inversion in band structure recently proposed for the Pbi-xSn^Te alloys. If E g is assigned negative values for samples in which the conduction and valence bands are inverted from those in PbSe, the data are well represented by the equation E Q = 0.13+ (4.5X10~4 deg"" 1 ) T~0.S9x eV.

Topological phase diagram and saddle point singularity in a tunable topological crystalline insulator

“…The sharp core level peaks indicate the high quality of the samples used for our measurements . For x values where the crystal has rocksalt structure, the electronic structure is known to have a direct band gap at the L points 28 . These are projected to theX points on the (001) surface, see Fig.…”

“…28,29 ). Low photon energy (15 eV-30 eV) and temperature dependent ARPES measurements for the low-lying electronic structures were performed at the Synchrotron Radiation Center (SRC) in Wisconsin and the Stanford Synchrotron Radiation Centre (SSRL) in California with R4000 electron analyzers whereas high photon energy (∼60 eV) measurements were performed at the Beamlines 12 and 10 at the Advanced Light Source (ALS) in California, equipped with high efficiency VG-Scienta SES2002 and R4000 electron analyzers.…”

Temperature-driven band inversion inPb0.77Sn0.23Se: Optical and Hall effect studies

“…3,13 On the basis of X-ray diffraction studies of annealed powders, it has been established 14,15 that the mixed alloy Pb 1−x Sn x Se stabilizes in the rock salt structure for 0 ≤ x ≤ 0.43 and that the minimum band gap remains at the L point. Infrared absorption measurements 16 find that the gap is a complex function of temperature and stoichiometric ratio x. An ARPES study 17 of Pb 0.77 Sn 0.23 Se finds that the band gap is temperature dependent, with a minimum around 100 K. The bulk band gap reopens at the L point with an inverted symmetry of the valence band (L − 6 ) and the conduction band (L + 6 ) as the temperature is further increased.…”

Surface-state-dominated transport in crystals of the topological crystalline insulator In-dopedPb1−xSnxTe

“…Thick (2-5 µm) films of (Pb 0.7 Sn 0.3 ) 1−y In y Te were grown on freshlycleaved Bi 2 Te 3 substrates 9 , using the open hot-wall epi- taxy method 23 and a single-source evaporator loaded with crushed single crystals of the desired composition. The substrate was kept at ∼ 300…”