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.

Correlation between oxygen isotope effects on transition temperature and magnetic penetration depth in high-temperature superconductors close to optimal doping

Abstract: The oxygen-isotope $(^{16}\mathrm{O}\text{\ensuremath{-}}^{18}\mathrm{O})$ effect (OIE) on the in-plane magnetic penetration depth ${\ensuremath{\lambda}}_{ab}(0)$ in optimally doped $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ and ${\mathrm{La}}_{1.85}{\mathrm{Sr}}_{0.15}\mathrm{Cu}{\mathrm{O}}_{4}$, and in slightly underdoped $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{4}{\mathrm{O}}_{8}$ and ${\mathrm{Y}}_{0.8}{\mathrm{Pr}}_{0.2}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ was studied by means of muon-spin rotation. A substantial OIE on ${\ensuremath{\lambda}}_{ab}(0)$ with an OIE exponent ${\ensuremath{\beta}}_{\mathrm{O}}=\ensuremath{-}d\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}{\ensuremath{\lambda}}_{ab}(0)∕d\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}{M}_{\mathrm{O}}\ensuremath{\approx}\ensuremath{-}0.2$ (${M}_{\mathrm{O}}$ is the mass of the oxygen isotope), and a small OIE on the transition temperature ${T}_{c}$ with an OIE exponent ${\ensuremath{\alpha}}_{\mathrm{O}}=\ensuremath{-}d\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}{T}_{c}∕d\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}{M}_{\mathrm{O}}\ensuremath{\simeq}0.02--0.1$ were observed. The observation of a substantial isotope effect on ${\ensuremath{\lambda}}_{ab}(0)$, even in cuprates where the OIE on ${T}_{c}$ is small, indicates that lattice effects play an important role in cuprate high-temperature superconductors.

Interference of electrons in backscattering through a quantum point contact

Abstract: Scanning gate microscopy is used to locally investigate electron transport in a high-mobility two-dimensional electron gas formed in a GaAs/AlGaAs heterostructure. Using quantum point contacts (QPC) we observe branches caused by electron backscattering decorated with interference fringes similar to previous observations by Topinka et al. We investigate the branches at different points of a conductance plateau as well as between plateaus, and demonstrate that the most dramatic changes in branch pattern occur at the low-energy side of the conductance plateaus. The branches disappear at magnetic fields as low as 50 mT demonstrating the importance of backscattering for the observation of the branching effect. The spacing between the interference fringes varies by more than 50% for different branches across scales of microns. Several scenarios are discussed to explain this observation.

Hysteretic magnetoresistance and thermal bistability in a magnetic two-dimensional hole system

Abstract: A study of Mn-doped InAs quantum wells reveals unexpected metastable behaviour of magnetotransport phenomena at sub-kelvin temperatures, in structures that show at the same time the quantum Hall effect in high magnetic fields. These findings bridge the physics of two-dimensional carrier systems with phenomena specific to magnetically doped semiconductors.

Investigation of conduction and relaxation phenomena in BaZrxTi1−xO3 (x=0.05) by impedance spectroscopy

Abstract: In present study we have prepared ferroelectric BaZr x Ti 1− x O 3 ( x =0.05) ceramic by conventional solid state reaction route and studied its electrical properties as a function of temperature and frequency. X-ray diffraction (XRD) analysis shows single-phase formation of the compound with orthorhombic crystal structure at room temperature. Impedance and electric modulus spectroscopy analysis in the frequency range of 40 Hz–1 MHz at high temperature (200–600 °C) suggests two relaxation processes with different time constant are involved which are attributed to bulk and grain boundary effects. Frequency dependent dielectric plot at different temperature shows normal variation with frequency while dielectric loss (tan δ ) peak was found to obey an Arrhenius law with activation energy of 1.02 eV. The frequency-dependent AC conductivity data were also analyzed in a wide temperature range.

Nanosecond-timescale spin transfer using individual electrons in a quadruple-quantum-dot device

Abstract: The ability to coherently transport electron-spin states between different sites of gate-defined semiconductor quantum dots is an essential ingredient for a quantum-dot-based quantum computer. Previous shuttles using electrostatic gating were too slow to move an electron within the spin dephasing time across an array. Here we report a nanosecond-timescale spin transfer of individual electrons across a quadruple-quantum-dot device. Utilizing enhanced relaxation rates at a so-called `hot spot', we can upper bound the shuttle time to at most 150 ns. While actual shuttle times are likely shorter, 150 ns is already fast enough to preserve spin coherence in e.g. silicon based quantum dots. This work therefore realizes an important prerequisite for coherent spin transfer in quantum dot arrays.