The superconducting transition temperature ${T}_{c}$ in Nb/Gd multilayers shows a pronounced nonmonotonic dependence on the ferromagnetic Gd layer thickness ${d}_{\mathrm{Gd}}$ for fixed Nb ${d}_{\mathrm{Nb}}$. For ${d}_{\mathrm{Nb}}=500 \mathrm{and} 600$ \AA{}, oscillation occurs range $10\ensuremath{\le}{d}_{\mathrm{Gd}}\ensuremath{\le}40$ \AA{} where ferromagnetism is well established. These results provide first evidence predicted $\ensuremath{\pi}$ phase superconductor/ferromagnet order...

Rectifying diodes of single nanobelt/nanowire-based devices have been fabricated by aligning ZnO nanobelts/nanowires across paired Au electrodes using dielectrophoresis. A current 0.5 μA at 1.5 V forward bias has received, and the diode can bear an applied voltage up to 10 V. The ideality factor is ∼3, on-to-off ratio as high 2000. detailed IV characteristics Schottky investigated low temperatures. formation suggested due asymmetric contacts formed in dielectrophoresis process.

We report an approach for growing aligned ZnO nanowire arrays with a high degree control over size, orientation, dimensionality, uniformity, and possibly shape. Our method combines e-beam lithography low temperature hydrothermal to achieve patterned growth of NWs at <100degreesC on general inorganic substrates, such as Si GaN, without using catalyst. This opens up the possibility applying nanowires sensor arrays, piezoelectric antenna two-dimensional photonic crystals, IC interconnects,...

Large-scale Ni-doped ZnO nanowire (NW) arrays are grown. The electrical conductivity of a single NW has been increased for 30 times. photoluminescence (PL) spectrum the doped NWs red shift, suggesting possible doping induced band edge bending. could be basis building integrated nanoscale transistors, sensors, and photodetectors.

Despite recent advances in quantum sciences, a master equation that accurately and simply characterizes open dynamics across extremely long timescales dispersive environments is still needed. In this study, we optimize the computation of fourth-order time-convolutionless to meet need. Early versions required computing multidimensional integral, limiting its use. Our accounts for simultaneous relaxation dephasing, resulting coefficients proportional system's spectral density over frequency...

The non-Markovian dynamics of an open quantum system can be rigorously derived using the Feynman–Vernon influence functional approach. Although this formalism is exact, practical numerical implementations often require compromises. time-convolutionless (TCL) master equation offers exact framework, yet its application typically relies on a perturbative expansion both time forward and backward state propagators. Due to significant computational effort involved—and scarcity analytical solutions...

The K-shell ionisation is investigated using an extension of the first-order time-dependent perturbation-theory treatment Moller (1932) taking Dirac plane waves for description incident and scattered protons Darwin approximation relativistic wavefunctions atomic electrons ejected electron. differential cross sections delta 2 sigma / k q d /dk, where wavenumber electron hq momentum change proton, are calculated. double section collisions in which a spin occurs less sharply peaked small q, has...

We use magnetic susceptibility and inelastic neutron scattering measurements to show that copper benzoate, Cu(${\mathrm{C}}_{6}$${\mathrm{D}}_{5}$COO${)}_{2}$\ensuremath{\cdot}${3\mathrm{D}}_{2}$O, is a quasi-one-dimensional S=1/2 antiferromagnet with an exchange constant J = 1.57 meV. Below T=0.8 K ferromagnetic contribution the marks onset of canted three-dimensional (3D) antiferromagnetic order. An external field suppresses this effect, measured in high shows only response chain. The...

We report a size-manipulable synthesis of single-crystalline nanorods/nanowires barium manganite (BaMnO(3)) and titanium (BaTi(1/2)Mn(1/2)O(3)) by using the composite-hydroxide-mediated approach. The cleanly yields nanorods with hexagonal perovskite structure. Typical have widths ranging between 50 100 nm, lengths can be easily controlled time temperature or adding small amount water during process. Resistance measurement shows that phase transition happened at 58 K on BaMnO(3)....

We have measured the electronic energy spectra of nm-scale Au particles using a new tunneling spectroscopy configuration. The particle diameters ranged from 5 to 9 nm, and at low energies spectrum is discrete, as expected by electron-in-a-box model. density resonances increases rapidly with energy, higher overlap forming broad resonances. Near Thouless merge into continuum. display Zeeman splitting in magnetic field. Surprisingly, $g$ factors ( $\ensuremath{\sim}0.3$) levels nanoparticles...

We present the first measurement results of a highly scaled, 90-nm silicon-germanium heterojunction bipolar transistor (SiGe HBT) operating at cryogenic temperatures as low 70 mK. The SiGe HBT exhibits transistor-like behavior down to mK, but below 40 K, transconductance suggests presence nonequilibrium transport mechanisms. Despite non-ideal base current temperatures, dc gain (β) > 1 is achieved for I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"...

We have used ultrasensitive susceptibility techniques and scanning Hall probe microscopy to study arrays of electrically isolated micron-sized superconducting rings. The magnetic moments produced by the supercurrents in these rings are analogous Ising spins, neighboring interact antiferromagnetically via their dipolar fields. find that there significant antiferromagnetic correlations between rings, effects due geometrical frustration can be observed. Quenched disorder also plays a role,...

The total and the differential cross section for elastic scattering of electrons on argon is calculated energies below ionization threshold. phase shifts were evaluated initially in frozen-core Hartree-Fock approximation. correlation corrections to them are found by solving integral equation reducible self-energy part one-particle Green's function; this procedure equivalent Schr\"odinger with optical potential. potential, being equal function, using many-body perturbation theory. Presented...

Understanding nonsecular dynamics in open quantum systems is addressed here, with emphasis on large numbers of Bohr frequencies, zero temperature, and fast driving. We employ the master equation, which replaces arithmetic averages decay rates system, their geometric averages, find that it can improve second order perturbation theory, known as Redfield while enforcing complete positivity dynamics. The characteristic frequency scale governs approximation minimax frequency: minimum maximum...

The non-Markovian dynamics of an open quantum system can be rigorously derived using the Feynman-Vernon influence functional approach. Although this formalism is exact, practical numerical implementations often require compromises. time-convolutionless (TCL) master equation offers exact framework, yet its application typically relies on a perturbative expansion both time forward and backward state propagators. Due to significant computational effort involved - scarcity analytical solutions...

We describe a fabrication technique in which nanoscale Au grain is connected to two Cr electrodes. Electron transport our samples can be fitted orthodox theory of single electron tunneling on particle. In one sample, we resolve additional steps current, are interpreted as discrete quantum states electrons added the grain.

We report the observation of oscillations in superconducting transition temperature ${T}_{c}$ Nb/Gd/Nb trilayers as Gd layer thickness ${d}_{\mathrm{Gd}}$ is varied. The minimum occurs at ${d}_{\mathrm{Gd}}\ensuremath{\approx}13$ \AA{}. results are consistent with our previous study Nb/Gd multilayers and support theoretical prediction a $\ensuremath{\pi}$-phase junction superconductor/ferromagnet/superconductor systems.

A formalism that allows the formulation of quantum mechanics in terms non-negative smoothed Wigner functions, a simple and straightforward way, is developed. It contains Husimi distributions as special case.

We investigate spin-polarized electron tunnelling through ensembles of nanometer scale Al grains embedded between two Co-reservoirs at 4.2K, and observe tunnelling-magnetoresistance (TMR) effects from spin-precession in the perpendicular applied magnetic field (the Hanle effect). The spin-coherence time ($T_2^\star$) measured using effect is order $ns$. dephasing attributed to local fields. Dephasing process does not destroy $TMR$, which strongly asymmetric with bias voltage. TMR explained...

The effects of Au grains on graphene conduction and doping are investigated. To obtain a clean Au-graphene contact, deposited over before any chemical processing. bulk the effective contact resistance versus gate voltage demonstrate that cause p-doping in graphene. Fermi level shift is disagreement with published first-principles calculations, larger than predicted separation between topmost layer. differential bias display anomalies at zero higher voltages, latter likely caused by inelastic...

The theoretical investigation carried out by Arthurs and Moiseiwitsch (1958) has been extended to higher energies atoms with greater nuclear charge Z. Allowance for the difference between experimental ionization arising from potential field of electrons in outer shells is made using a similar procedure that due Perlman (1960). authors have calculated K-shell cross sections as functions electron impact energy C, Al, Ni, Cu, Ag, Sn, Au compared their curves available data, accordance being...

In quantum computing, metrology, single-photon counting, and nanomechanics, weak electronic signals at extremely low temperatures need amplification. To this end, the authors build study silicon-germanium heterojunction bipolar transistors, which offer excellent amplifier characteristics, integrability with silicon electronics, cost, manufacturability. Their research junction of physics electrical engineering is a step toward next-generation integrated circuits 90-nm scale for temperature regime.