Search results for "INSULATOR"

Epigenetics: More than Genetics

2008

Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

2017

Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral $p_x$ + i$p_y$ wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi$_2$Te$_3$ topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral $p_x$ + i$p_y$ component. The magnetic field pattern of the junctions shows a dip at zero externally a…

Short range charge/orbital ordering in La1−xSrxMn1−zBzO3 (B = Cu,Zn) manganites

2005

We have measured the reflectivity spectra of La1−x SrxMn1−zBzO3 (B = Cu, Zn; 0.17 x 0.30; 0 z 0.10) manganites over wide frequency (100–4000 cm −1 )a nd temperature (80–300 K) ranges. Besides the previously observed infrared active modes or mode pairs at about 160 cm −1 (external mode), 350 cm −1 (bond bending mode) and 590 cm −1 (bond stretching mode), we have clearly observed two additional phonon modes at about 645 and 720 cm −1 below the temperature T1 (T1 < TC), which coincides with the phase transition temperature when the system transforms from ferromagnetic metallic into a ferromagnetic insulator state. This transition is related to the formation of short range charge/orbitally orde…

Interfacial Dzyaloshinskii-Moriya interaction and chiral magnetic textures in a ferrimagnetic insulator

2019

The interfacial Dzyaloshinskii-Moriya interaction (DMI) in multilayers of heavy metal and ferromagnetic metals enables the stabilization of novel chiral spin structures such as skyrmions. Magnetic insulators, on the other hand can exhibit enhanced dynamics and properties such as lower magnetic damping and therefore it is of interest to combine the properties enabled by interfacial DMI with insulating systems. Here, we demonstrate the presence of interfacial DMI in heterostructures that include insulating magnetic layers. We use a bilayer of perpendicularly magnetized insulating thulium iron garnet (TmIG) and the heavy metal platinum, and find a surprisingly strong interfacial DMI that, comb…

Thin film growth and band lineup of In2O3 on the layered semiconductor InSe

1999

Thin films of the transparent conducting oxide In2O3 have been prepared in ultrahigh vacuum by reactive evaporation of indium. X-ray diffraction, optical, and electrical measurements were used to characterize properties of films deposited on transparent insulating mica substrates under variation of the oxygen pressure. Photoelectron spectroscopy was used to investigate in situ the interface formation between In2O3 and the layered semiconductor InSe. For thick In2O3 films a work function of φ = 4.3 eV and a surface Fermi level position of EF−EV = 3.0 eV is determined, giving an ionization potential IP = 7.3 eV and an electron affinity χ = 3.7 eV. The interface exhibits a type I band alignmen…

Origin of pressure-induced insulator-to-metal transition in the van der Waals compound FePS3 from first-principles calculations

2020

The authors acknowledge the assistance of the University Computer Center of Saint‐Petersburg State University in the accomplishment of high‐performance computations. A.K. is grateful to the Latvian Council of Science project no. lzp‐2018/2‐0353 for financial support.

Experimental evidence of high spatial confinement of elastic energy in a phononic cantilever

2021

We report on experimental high spatial confinement of elastic energy in a silicon phononic cantilever for which the quality factor of a higher-order flexural resonance is increased by a factor of 27 (from Q ∼ 80 to Q ∼ 2130) with the use of a three-row phononic crystal (PnC) strip. As shown by numerical simulations performed with the finite element method, the PnC both reduces anchor loss and confines elastic energy inside the cantilever. The PnC and the cantilever are fabricated with standard clean room techniques on a silicon on insulator substrate. Optical measurements of the out-of-plane displacements are performed with a laser scanning interferometer in a frequency range around 2 MHz.

High-Mobility Ambipolar Magnetotransport in Topological Insulator Bi2Se3 Nanoribbons

2021

Nanoribbons of topological insulators (TIs) have been suggested for a variety of applications exploiting the properties of the topologically protected surface Dirac states. In these proposals it is crucial to achieve a high tunability of the Fermi energy, through the Dirac point while preserving a high mobility of the involved carriers. Tunable transport in TI nanoribbons has been achieved by chemical doping of the materials so to reduce the bulk carriers' concentration, however at the expense of the mobility of the surface Dirac electrons, which is substantially reduced. Here we study bare ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ nanoribbons transferred on a variety of oxide substrates and dem…

Heusler Compounds at a Glance

2013

The class of Heusler compounds, including the XYZ and the X 2 YZ compounds, does not only have an endless number of members, but also a vast variety of properties can be found in this class of materials, ranging from semi-conductors, half-metallic ferromagnets, superconductors, and topological insulators to shape memory alloys. With this chapter, we would like to provide an overview of Heusler compounds, focusing on basis design principles, their properties and potential applications.

Magnetic Heusler Compounds

2013

Abstract Heusler compounds are a remarkable class of intermetallic materials with 1:1:1 (often called Half-Heusler) or 2:1:1 composition comprising more than 1500 members. New properties and potential fields of applications emerge constantly; the prediction of topological insulators is the most recent example. Surprisingly, the properties of many Heusler compounds can easily be predicted by the valence electron count or within a rigid band approach. The wide range of the multifunctional properties of Heusler compounds is reflected in extraordinary magnetooptical, magnetoelectronic, and magnetocaloric properties. Co 2 -Heusler compounds are predicted and proven half-metallic ferromagnets sho…