Search results for "upe"
showing 10 items of 7447 documents
Piezo-electrical control of gyration dynamics of magnetic vortices
2019
In this work, we first statically image the electrically controlled magnetostatic configuration of magnetic vortex states and then we dynamically image the time-resolved vortex core gyration tuned by electric fields. We demonstrate the manipulation of the vortex core gyration orbit by engineering the magnetic anisotropies. We achieve this by electric fields in a synthetic heterostructure consisting of a piezoelement coupled with magnetostrictive microstructures, where the magnetic anisotropy can be controlled by strain. We directly show the strong impact of the tailored anisotropy on the static shape of the vortex state and the dynamic vortex core orbit. The results demonstrate the possibil…
Towards quantum phase slip based standard of electric current
2019
An accurate standard of electric current is a long-standing challenge of modern metrology. It has been predicted that a superconducting nanowire in the regime of quantum fluctuations can be considered as the dynamic equivalent of a chain of conventional Josephson junctions. In full analogy with the quantum standard of electric voltage based on the Josephson effect, the quantum phase slip phenomenon in ultrathin superconducting nanowires could be used for building the quantum standard of electric current. This work presents advances toward this ultimate goal.
Lead evaporation instabilities and failure mechanisms of the micro oven at the GTS-LHC ECR ion source at CERN
2020
The GTS-LHC ECR ion source (named after the Grenoble Test Source and the Large Hadron Collider) at CERN provides heavy ion beams for the chain of accelerators from Linac3 up to the LHC for high energy collision experiments and to the Super Proton Synchrotron for fixed target experiments. During the standard operation, the oven technique is used to evaporate lead into the source plasma to produce multiple charged lead ion beams. Intensity and stability are key parameters for the beam, and the operational experience is that some of the source instabilities can be linked to the oven performance. Over long operation periods of several weeks, the evaporation is not stable which makes the tuning …
Deposition of binder-free oxygen-vacancies NiCo2O4 based films with hollow microspheres via solution precursor thermal spray for supercapacitors
2019
Abstract Hollow micro-/nanostructures and oxygen vacancies are highly desirable for supercapacitors due to high active surface area and outstanding electrochemical properties. In order to benefiting from the both effect, binder-free oxygen-vacancies NiCo2O4 based films with hollow microspheres were pioneering directly deposited via one kind thermal spray technology, named solution precursor thermal spray (SPTS) process. To our best knowledge, the rapid one-step SPTS route was firstly employed to synthesize and deposit NiCo2O4 films for supercapacitor applications. The CV data clearly demonstrated that the specific capacitances of more oxygen-deficient NiCo2O4 electrodes with hollow microsph…
High transparency Bi 2 Se 3 topological insulator nanoribbon Josephson junctions with low resistive noise properties
2019
Bi$_2$Se$_3$ nanoribbons, grown by catalyst-free Physical Vapour Deposition, have been used to fabricate high quality Josephson junctions with Al superconducting electrodes. The conductance spectra (dI/dV) of the junctions show clear dip-peak structures characteristic of multiple Andreev reflections. The temperature dependence of the dip-peak features reveals a highly transparent Al/Bi$_2$Se$_3$ topological insulator nanoribbon interface and Josephson junction barrier. This is supported by the high values of the Bi$_2$Se$_3$ induced gap and of I$_c$R$_n$ (I$_c$ critical current, R$_n$ normal resistance of the junction) product both of the order of 160 $\mu$eV, a value close to the Al gap. T…
Color centers in diamond as novel probes of superconductivity
2018
Magnetic imaging using color centers in diamond through both scanning and wide-field methods offers a combination of unique capabilities for studying superconductivity, for example, enabling accurate vector magnetometry at high temperature or high pressure, with spatial resolution down to the nanometer scale. The paper briefly reviews various experimental modalities in this rapidly developing nascent field and provides an outlook towards possible future directions.
Simplified feedback control system for scanning tunneling microscopy
2021
A Scanning Tunneling Microscope (STM) is one of the most important scanning probe tools available to study and manipulate matter at the nanoscale. In a STM, a tip is scanned on top of a surface with a separation of a few \AA. Often, the tunneling current between tip and sample is maintained constant by modifying the distance between the tip apex and the surface through a feedback mechanism acting on a piezoelectric transducer. This produces very detailed images of the electronic properties of the surface. The feedback mechanism is nearly always made using a digital processing circuit separate from the user computer. Here we discuss another approach, using a computer and data acquisition thr…
Broadband Ultrahigh-Resolution Spectroscopy of Particle-Induced X Rays: Extending the Limits of Nondestructive Analysis
2016
Nondestructive analysis (NDA) based on x-ray emission is widely used, for example, in the semiconductor and concrete industries. Here, we demonstrate significant quantitative and qualitative improvements in broadband x-ray NDA by combining particle-induced emission with detection based on superconducting microcalorimeter arrays. We show that the technique offers great promise in the elemental analysis of thin-film and bulk samples, especially in the difficult cases where tens of different elements with nearly overlapping emission lines have to be identified down to trace concentrations. We demonstrate the efficiency and resolving capabilities by spectroscopy of several complex multielement …
Enhanced alignment and orientation of polar molecules by vibrational resonant adiabatic passage
2007
The authors show that polar molecules can be adiabatically aligned and oriented by laser pulses more efficiently when the laser frequencies are vibrationally resonant. The aligned molecules are found in a superposition of vibrational pendular states, each associated with the alignment of the rotor in one vibrational state. The authors construct the dressed potential associated with this mechanism. Values of detunings and field amplitudes are given to optimize the degree of alignment and orientation for the CO molecule.
Direct mass measurements and ionization potential measurements of the actinides
2019
Abstract The precise determination of atomic and nuclear properties such as masses, differential charge radii, nuclear spins, electromagnetic moments and the ionization potential of the actinides has been extended to the late actinides in recent years. In particular, laser spectroscopy and mass spectrometry have reached the region of heavy actinides that can only be produced only at accelerator facilities. The new results provide deeper insight into the impact of relativistic effects on the atomic structure and the evolution of nuclear shell effects around the deformed neutron shell closure at N = 152. All these experimental activities have also opened the door to extend such measurements t…