Solid State Physics Laboratory

About: Solid State Physics Laboratory is a facility organization based out in Delhi, India. It is known for research contribution in the topics: Quantum dot & Dielectric. The organization has 1754 authors who have published 2597 publications receiving 50601 citations.

Characterization of spin-orbit interactions of GaAs heavy holes using a quantum point contact.

Abstract: We present transport experiments performed in high-quality quantum point contacts embedded in a GaAs two-dimensional hole gas. The strong spin-orbit interaction results in peculiar transport phenomena, including the previously observed anisotropic Zeeman splitting and level-dependent effective g factors. Here we find additional effects, namely, the crossing and the anticrossing of spin-split levels depending on subband index and magnetic field direction. Our experimental observations are reconciled in a heavy-hole effective spin-orbit Hamiltonian where cubic- and quadratic-in-momentum terms appear. The spin-orbit components, being of great importance for quantum computing applications, are characterized in terms of magnitude and spin structure. In light of our results, we explain the level-dependent effective g factor in an in-plane field. Through a tilted magnetic field analysis, we show that the quantum point contact out-of-plane g factor saturates around the predicted 7.2 bulk value.

Mossbauer isomer-shifts and quadrupole splittings in the amorphous iron-boron system

Abstract: The isomer shifts and quadrupoole splittings of amorphous Fe x B 1−x alloys (10 a/o ⪅ × ⪅ 90 a/o) were studied by 57 Fe Mossbauer spectroscopy. The isomer shift vs. composition can be described by the ▵φ ∗− and ▵n WS -terms of Miedema's cellular model to predict the heat of formation of binary alloys and an additional volume mismatch term. This term is necessary for boron-rich alloys ( x ⪅ 50 a/o). We conclude that these samples have a strained atomic structure. The values of the quadrupole splittings at the boron-rich side increase strongly, indicating that the Fe-atoms are squeezed into asymmetric atomic surroundings. Implanted iron into crystalline boron has a comparable isomer shift and quadrupole splitting as the boron-rich alloys.

C-axis infrared response of tl2ba2ca2cu3o10 studied by oblique-incidence polarized-reflectivity measurements

Abstract: We show that from measurements of the reflectivity of a uniaxial medium taken at a finite incidence angle with s- and p-polarized light it is possible to determine the dielectric function both parallel and perpendicular to the optical axis. When applied to layered compounds with its surface parallel to the layers, this technique allows for an accurate determination of the loss function perpendicular to the layers. This is demonstrated for the example of c-axis oriented thin films of the high-${\mathit{T}}_{\mathit{c}}$ superconductor ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{10}$, on which we carried out polarized reflectivity measurements at 45\ifmmode^\circ\else\textdegree\fi{} incidence angle above and below ${\mathit{T}}_{\mathit{c}}$.

Anharmonicity and self-energy effects of the E 2 g phonon in Mg B 2

Abstract: We present a Raman scattering study of the ${E}_{2g}$ phonon anharmonicity and of superconductivity-induced self-energy effects in $\mathrm{Mg}{\mathrm{B}}_{2}$ single crystals. We show that anharmonic two-phonon decay is mainly responsible for the unusually large linewidth of the ${E}_{2g}$ mode. We observe $\ensuremath{\sim}2.5%$ hardening of the ${E}_{2g}$ phonon frequency upon cooling into the superconducting state and estimate the electron-phonon coupling strength associated with this renormalization.

Electron-avalanche amplifier based on the electronic Venturi effect

Abstract: Scattering of otherwise ballistic electrons far from equilibrium is investigated in a cold two-dimensional electron system. The interaction between excited electrons and the degenerate Fermi liquid induces a positive charge in a nanoscale region which would be negatively charged for diffusive transport at local thermal equilibrium. In a three-terminal device we observe avalanche amplification of electrical current, resulting in a situation comparable to the Venturi effect in hydrodynamics. Numerical calculations using a random-phase approximation are in agreement with our data and suggest Coulomb interaction as the dominant scattering mechanism.