Related papers: Ultrafast carrier-lattice interactions and interla…
Bismuth selenide (Bi2Se3) is a prototypical three-dimensional topological insulator whose Dirac surface states have been extensively studied theoretically and experimentally. Surprisingly little, however, is known about the energetics and…
Transient reflectivity measurements of thin films, ranging from 6 to 40 nm in thickness, of the topological insulator Bi2Se3 revealed a strong dependence of the carrier relaxation time on the film thickness. For thicker films the relaxation…
Ultrafast carrier dynamics in the topological insulator Bi2Se3 have recently been intensively studied using a variety of techniques. However, we are not aware of any successful experiments exploiting transient absorption (TA) spectroscopy…
Transient reflectivity (TR) from thin films (6 - 40 nm thick) of the topological insulator Bi2Se3 reveal ultrafast carrier dynamics, which suggest the existence of both radiative and non-radiative recombination between electrons residing in…
We discuss the ultrafast evolution of the surface electronic structure of the topological insulator Bi$_2$Te$_3$ following a femtosecond laser excitation. Using time and angle resolved photoelectron spectroscopy, we provide a direct…
Topologically protected surface states have garnered significant attention due to their robustness against perturbations and potential applications in optoelectronics. Bi2 Bi2Se3 is a topological semimetal composed of a 2D bismuthene sheet…
We have investigated the transport properties of topological insulator Bi2Se3 thin films grown using magnetron sputtering with an emphasis on understanding the behavior as a function of thickness. We show that thickness has a strong…
Ultra-thin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak Van der Waals interaction between adjacent quintuple…
Band structure engineering and interfacial buffer layers have been demonstrated as effective means to tune the Fermi level in topological insulators (TI). In particular, the charge compensated compound (BixSb1-x)2Te3 (BST) plays a critical…
Ultrafast carrier relaxation in the 2D topological insulator (TI) Bi2Se3 [gapped Dirac surface states (SS)] and how it inherits ultrafast relaxation in the 3D TI Bi2Se3 (gapless Dirac SS) remains a challenge for developing new…
Individual relaxation dynamics of electrons and holes in optically pumped semiconductors is rarely observed due to their overlap. Here we report the individual dynamics of long-lived (~200 mks) holes observed at room temperature in a 10 nm…
Three-dimensional (3-D) topological insulators (TI) are characterized by the presence of metallic surface states and a bulk band gap. Recently theoretical and experimental studies have shown an induced gap in the surface state bands of TI…
Above-bandgap femtosecond optical excitation of a ferroelectric/dielectric BaTiO3/CaTiO3 superlattice leads to structural responses that are a consequence of the screening of the strong electrostatic coupling between the component layers.…
Elastic strain has the potential for a controlled manipulation of the band gap and spin-polarized Dirac states of topological materials, which can lead to pseudo-magnetic-field effects, helical flat bands and topological phase transitions.…
We investigated the Dirac-cone state and its modulation when an ultrathin film of topological insulator Bi2Se3 was epitaxially grown on a van-der-Waals ferromagnet Cr2Si2Te6 (CST) by angle-resolved photoemission spectroscopy. We observed a…
Driven quantum materials with on demand properties controlled by external stimuli are critical for emergent quantum technology. In optically tunable superconducting heterostructures, the lattice responses at the buried interface may hold…
Topological insulators are insulating in the bulk but possess metallic surface states protected by time-reversal symmetry. Here, we report a detailed electronic transport study in high quality Bi2Se3 topological insulator thin films…
Transient reflectivity (TR) measured at laser photon energy 1.51 eV from the indirectly intersurface coupled topological insulator Bi2-xMnxSe3 films (12 nm thick) revealed a strong dependence of the rise-time and initial decay-time…
Bi2O2Se has attracted intensive attention due to its potential in electronics, optoelectronics, as well as ferroelectric applications. Despite that, there have only been a handful of experimental studies based on ultrafast spectroscopy to…
Thermoelectric (TE) devices have been attracting increasing attention because of their ability to convert heat directly to electricity. To date, improving the TE figure of merit remains the key challenge. The advent of the topological…