gg-factor engineering with InAsSb alloys toward zero band gap limit

Band gap is known as an effective parameter for tuning the Lande $g$-factor in semiconductors and can be manipulated in a wide range through the bowing effect in ternary alloys. In this work, using the recently developed virtual substrate technique, high-quality InAsSb alloys throughout the whole Sb composition range are fabricated and a large $g$-factor of $g\approx -90$ at the minimum band gap of $\sim 0.1$ eV, which is almost twice that in bulk InSb is found. Further analysis to the zero gap limit reveals a possible gigantic $g$-factor of $g\approx -200$ with a peculiar relativistic Zeeman effect that disperses as the square root of magnetic field. Such a $g$-factor enhancement toward the narrow gap limit cannot be quantitatively described by the conventional Roth formula, as the orbital interaction effect between the nearly triply degenerated bands becomes the dominant source for the Zeeman splitting. These results may provide new insights into realizing large $g$-factors and spin polarized states in semiconductors and topological materials

Giant gg-factors and fully spin-polarized states in metamorphic short-period InAsSb/InSb superlattices

Realizing a large Land\'{e} $g$-factor of electrons in solid-state materials has long been thought of as a rewarding task as it can trigger abundant immediate applications in spintronics and quantum computing. Here, by using metamorphic InAsSb/InSb superlattices (SLs), we demonstrate an unprecedented high value of $g\approx 104$, twice larger than that in bulk InSb, and fully spin-polarized states at low magnetic fields. In addition, we show that the $g$-factor can be tuned on demand from 20 to 110 via varying the SL period. The key ingredients of such a wide tunability are the wavefunction mixing and overlap between the electron and hole states, which have drawn little attention in prior studies. Our work not only establishes metamorphic InAsSb/InSb as a promising and competitive material platform for future quantum devices but also provides a new route toward $g$-factor engineering in semiconductor structures

Broadband optical and terahertz properties of 1D van der Waals heteronanotubes

ID van der Waals heterostructures composed of SWCNT, boron nitride nanotube (BNNT), and molybdenum disulfide nanotube (MoS 2 NT) is a novel material which attracts attention due to the unique properties. In particular, by com-paring C@BN NT and SWCNT@BNNT@MoS 2 NT with MoS 2 flakes, we found that 1D van der Waals heterostructures exhibited optical properties uniquely associated with with their 1D and heterostructure nature

Engineering Dirac Materials: Metamorphic InAs_1–<i>x</i>Sb_<i>x</i>/InAs_1–<i>y</i>Sb_<i>y</i> Superlattices with Ultralow Bandgap

Quasiparticles with Dirac-type dispersion can be observed in nearly gapless bulk semiconductors alloys in which the bandgap is controlled through the material composition. We demonstrate that the Dirac dispersion can be realized in short-period InAs_1–<i>x</i>Sb_<i>x</i>/InAs_1–<i>y</i>Sb_<i>y</i> metamorphic superlattices with the bandgap tuned to zero by adjusting the superlattice period and layer strain. The new material has anisotropic carrier dispersion: the carrier energy associated with the in-plane motion is proportional to the wave vector and characterized by the Fermi velocity <i>v</i>_F, and the dispersion corresponding to the motion in the growth direction is quadratic. Experimental estimate of the Fermi velocity gives <i>v</i>_F = 6.7 × 10⁵ m/s. Remarkably, the Fermi velocity in this system can be controlled by varying the overlap between electron and hole states in the superlattice. Extreme design flexibility makes the short-period metamorphic InAs_1–<i>x</i>Sb_<i>x</i>/InAs_1–<i>y</i>Sb_<i>y</i> superlattice a new prospective platform for studying the effects of charge-carrier chirality and topologically nontrivial states in structures with the inverted bandgaps