electrons flow from the anode through a circuit outside the battery and back into the cathode.
Having lost the electrons that are generating the current, some of the atoms in the anode--an electrically conductive metal like lithium--become ions that then travel to the cathode,
and magnetization in order to understand how to control electron spins (electron magnetic moments) and to create the new generation of electronics.
In spin electronics-or spintronics-information is coded via the electron spin, which could be directed along
that the spins of the electron and of other charged particles are very difficult to control.
During the experiments scientists bombarded the experimental samples with muons (particles that resemble electrons, but are 200 times heavier) and analyzed their dissipation scattering.
or high-energy reservoir of electrons. Lithium can do that, as the charge carrier whose ions migrate into the graphite
This finding is likely to spawn new developments in emerging technologies such as low-power electronics based on the spin of electrons or ultrafast quantum computers.
"The electrons in topological insulators have unique quantum properties that many scientists believe will be useful for developing spin-based electronics and quantum computers.
In Science Advances, the researchers report the discovery of an optical effect that allows them to"tune"the energy of electrons in these materials using light,
which arises from quantum interference between the different simultaneous paths electrons can take through a material
and electrons to read data. This could enable the size of storage cells to be reduced to atomic dimensions.
Standard memory devices are based on electrons which are displaced by applying voltage. The development of ever smaller and more energy-efficient storage devices according to this principle,
"Electrons are roughly 1000 times lighter than ions and so they move much more easily under the influence of an external voltage.
while the electrons remain mobile and can be used to read the storage status."The trick:
"The tunnel effect enables us to move electrons through the ultra-thin layer with very little energy,
and electrons, on the other hand, at voltages far below one volt. This way, ions can be used specifically for storing and electrons specifically for reading data.
The researchers also reported that their research had another very interesting element. The new resistance-based storage devices could even simulate brain structures.
They suggested that magnetic atoms introduced into a superconductor must create special states of excitation around themselves-electron-hole standing waves named after their discoverers.
One promising option is to use topologically protected electron states that are resistant to decoherence.
The theory predicts that such non-Abelian anyons may occur in a two-dimensional"liquid"of electrons in a superconductor under the influence of a local magnetic field.
The electron liquid thus becomes degenerate, i e. the electrons can have different states at the same energy level.
The superposition of several anyons cannot be affected without moving them, therefore they are protected completely from disturbances e
This phase, characterized by an unusual ordering of electrons, offers possibilities for new electronic device functionalities and could hold the solution to a longstanding mystery in condensed matter physics having to do with high-temperature superconductivity--the ability
first consider a crystal with electrons moving around throughout its interior. Under certain conditions, it can be energetically favorable for these electrical charges to pile up in a regular,
In addition to charge, electrons also have a degree of freedom known as spin. When spins line up parallel to each other (in a crystal, for example),
But what if the electrons in a material are ordered not in one of those ways?
And like the cuprates, iridates are electrically insulating antiferromagnets that become increasingly metallic as electrons are added to
where an additional amount of energy is required to strip electrons out of the material. For decades, scientists have debated the origin of the pseudogap
but uses photons--the quanta of light--instead of electrons. The biggest advantage of using photons is the absence of interactions between them.
As a consequence, photons address the data transmission problem better than electrons. This property can primarily be used for in computing where IPS (instructions per second) is the main attribute to be maximized.
--Free carriers (electrons and electron holes) place serious restrictions on the speed of signal conversion in the traditional integrated photonics.
Film in 4-D with ultrashort electron pulses Physicists of the Ludwig-Maximilians-Universität (LMU) in Munich shorten electron pulses down to 30 femtoseconds duration.
A team from Ludwig-Maximilians-Universität (LMU) and Max Planck Institute of Quantum Optics (MPQ) has managed now to shorten electron pulses down to 28 femtoseconds in duration.
Sharp images of moving atoms Electrons are odd particles: they have both wave and particle properties.
They create beams of electron pulses, which can, due to their extremely short flashing, provide us with very sharp images of moving atoms and electrons.
Nevertheless, some of the fastest processes still remained blurred. Those who want to explore the microcosm
Scientists from the Laboratory for Attosecond Physics at LMU and MPQ have succeeded now in producing ultrashort electron pulses with a duration of only 28 femtoseconds.
If such electrons meet a molecule or atom, they are diffracted into specific directions due to their short wavelength.
the physicists applied their ultrashort electron pulses to a biomolecule in a diffraction experiment. It is planned to use those electron beams for pump-probe experiments:
an optical laser pulse is sent to the sample, initiating a response. Shortly afterwards the electron pulses produce a diffraction image of the structure at a sharp instant in time.
A large amount of such snapshots at varying delay times between the initiating laser pulses and the electron pulses then results in a film showing the atomic motion within the substance.
Thanks to the subatomic wavelength of the electrons, one therefore obtains a spatial image as well as the dynamics.
Altogether this results in a four-dimensional impression of molecules and their atomic motions during a reaction. ith our ultrashort electron pulses
we are now able to gain a much more detailed insight into processes happening within solids and molecules than before,
"Now the physicists aim to further reduce the duration of their electron pulses. The shorter the shutter speed becomes, the faster the motions
The aim of the scientists is to eventually observe even the much faster motions of electrons in light-driven processes o
which use photons instead of electrons to transport and manipulate information, offer many advantages compared to traditional electronic links found in today computers.
which strongly effects the propagation of light, in the same way that semiconductors control the flow of electrons.
including irradiation with electrons and ions, but none of them worked. So far, the oxygen plasma approach worked the best,
"the bacteria can load electrons onto and discharge electrons from microscopic particles of magnetite. This discovery holds out the potential of using this mechanism to help clean up environmental pollution,
The flow of electrons is critical to the existence of all life and the fact that magnetite can be considered to be redox active opens up the possibility of bacteria being able to exist
phototrophic iron-oxidizing bacteria removed electrons from the magnetite, thereby discharging it. During the nighttime conditions, the iron-reducing bacteria took over
and were able to dump electrons back onto the magnetite and recharge it for the following cycle.
In principle, they are miniaturized extremely electron storage units. qdots can be produced using the same techniques as normal computer chips.
it is only necessary to miniaturize the structures on the chips until they hold just one single electron (in a conventional PC it is 10 to 100 electrons.
The electron stored in a qdot can take on states that are predicted by quantum theory. However, they are very short-lived:
#A quantum sensor for nanoscale electron transport The word defect doesnt usually have a good connotation--often indicating failure.
Graphic depiction of NV center sensors (red glowing spheres) used to probe electron motion in a conductor.
In this experiment, physicists harness the sensitivity of these isolated quantum systems to characterize electron motion.
At temperatures above absolute zero, the electrons inside of the silver layer (or any conductor) bounce around
Since electrons are charged particles, their motion results in fluctuating magnetic fields, which extend outside of the conductor.
which tells them about the electron behavior at a very small length scale. Like any good sensor, the NV centers are almost completely non-invasivetheir read-out with laser light does not disturb the sample they are sensing.
thus electrons travel dont travel very far--roughly 10 nanometers or less--before scattering off an obstacle.
and electrons can travel over 100 times farther. The electron movement, and corresponding magnetic field noise from the single silver crystal is a departure from so-called Ohmic predictions of the polycrystalline case,
and the team was able to explore both of these extremes non-invasively. These results demonstrate that single NV centers can be used to directly study electron behavior inside of a conductive material on the nanometer length scale.
Notably, this technique does not require electrical leads, applied voltages, or even physical contact with the sample of interest,
As the focused electron beam passed through the object it excited the crescent energetically, causing it to emit photons, a process known as cathodoluminescence.
which part of the object the electron beam excited, Atre said. For instance, the gold shell at the base of the object emitted photons of shorter wavelengths than
The technique can be used to probe many systems in which light is emitted upon electron excitation."
"This is an electron wave in a phosphorus atom, distorted by a local electric field. Unlike conventional computers that store data on transistors and hard drives, quantum computers encode data in the quantum states of microscopic objects called qubits.
Associate professor Morello said the method works by distorting the shape of the electron cloud attached to the atom,
which the electron responds.""Therefore, we can selectively choose which qubit to operate. It's a bit like selecting which radio station we tune to,
Attempts to use polymers with benzene-like delocalised electron bonding alleviated issues around the thermal durability to a certain extent.
They used a fused ring system of molecules with benzene-like delocalised electron bonding so that the material would readily crystallise.
This interaction leads to a rapid creation of an electron distribution with an elevated electron temperature.
and rapidly converted into electron heat. Next, the electron heat is converted into a voltage at the interface of two graphene regions with different doping.
This photo-thermoelectric effect turns out to occur almost instantaneously, thus enabling the ultrafast conversion of absorbed light into electrical signals.
which rely on the drift and diffusion of electrons and their holes through semiconducting material, memristor operation is based on ionic movement,
The ionic memory mechanism brings several advantages over purely electron-based memories which makes it very attractive for artificial neural network implementation,
he said. ons are also much heavier than electrons and do not tunnel easily, which permits aggressive scaling of memristors without sacrificing analog properties.
#Researchers create first whispering gallery for graphene electrons (Nanowerk News) An international research group led by scientists at the U s. Commerce departments National Institute of Standards
and Technology (NIST) has developed a technique for creating nanoscale whispering galleries for electrons in graphene. The development opens the way to building devices that focus
and amplify electrons just as lenses focus light and resonators (like the body of a guitar) amplify sound.
issue of Science("Creating and probing electron whispering-gallery modes in graphene")."An international research group led by scientists at NIST has developed a technique for creating nanoscale whispering galleries for electrons in graphene.
The researchers used the voltage from a scanning tunneling microscope (right) to push graphene electrons out of a nanoscale area to create the whispering gallery (represented by the protuberances on the left),
which is like a circular wall of mirrors to the electron. Image: Jon Wyrick, CNST/NIST) In some structures,
such as the dome in St pauls Cathedral in London, a person standing near a curved wall can hear the faintest sound made along any other part of that wall.
These whispering galleries are unlike anything you see in any other electron based system, and thats really exciting.
However, early studies of the behavior of electrons in graphene were hampered by defects in the material.
When moving electrons encounter a potential barrier in conventional semiconductors it takes an increase in energy for the electron to continue flowing.
As a result, they are reflected often, just as one would expect from a ball-like particle.
However, because electrons can sometimes behave like a wave, there is a calculable chance that they will ignore the barrier altogether,
Due to the light-like properties of graphene electrons, they can pass through unimpededno matter how high the barrierif they hit the barrier head on.
This tendency to tunnel makes it hard to steer electrons in graphene. Enter the graphene electron whispering gallery.
To create a whispering gallery in graphene the team first enriched the graphene with electrons from a conductive plate mounted below it.
With the graphene now crackling with electrons, the research team used the voltage from a scanning tunneling microscope (STM) to push some of them out of a nanoscale-sized area.
This created the whispering gallery, which is like a circular wall of mirrors to the electron.
An electron that hits the step head-on can tunnel straight through it, said NIST researcher Nikolai Zhitenev.
But if electrons hit it at an angle, their waves can be reflected and travel along the sides of the curved walls of the barrier until they began to interfere with one another,
creating a nanoscale electronic whispering gallery mode. The team can control the size and strength, i e.,
when hit with an electron beam. Equally importantly they have discovered how and why it happens.
When the electron beam hits the molecules on the surface it causes them to form an additional bond with their neighbors,
Argonne researchers are able to fold gold nanoparticle membranes in a specific direction using an electron beam
They envision zapping only a small part of the structure with the electron beam, designing the stresses to achieve particular bending patterns.
As a conductor, graphene lets electrons zip too fasthere no controlling or stopping themhile boron nitride nanotubes are
so insulating that electrons are rebuffed like an overeager dog hitting the patio door. But together, these two materials make a workable digital switch
which is the basis for controlling electrons in computers, phones, medical equipment and other electronics.
or differences in how much energy it takes to excite an electron in the material. hen we put them together,
you form a band gap mismatchhat creates a so-called otential barrierthat stops electrons. The band gap mismatch results from the materialsstructure:
caused by the difference in electron movement as currents move next to and past the hairlike boron nitride nanotubes.
These points of contact between the materialsalled heterojunctionsre what make the digital on/off switch possible. magine the electrons are like cars driving across a smooth track,
With their aligned atoms, the graphene-nanotube digital switches could avoid the issues of electron scattering. ou want to control the direction of the electrons,
slows down and redirects electrons. his is difficult in high speed environments, and the electron scattering reduces the number and speed of electrons.
Much like an arcade enthusiast, Yap says he and his team will continue trying to find ways to outsmart
or change the pinball setup of graphene to minimize electron scattering. And one day all their tweaks could make for faster computersnd digital pinball gamesor the rest of us t
and electrons in metal surfaces to develop novel components for optical data transmission between chips. The project is funded under the 7th Research Framework Programme of the European union
"The cloud of free-moving electrons around a metal that carries an electrical current can also absorb passing photons.
but their electrons absorb fewer passing photons.""While this extremely localised and directed heating effect has been put to some good uses like targeting cancerous cells to kill them,
First, the control voltage mediates how electrons pass through a boundary that can flip from an ohmic (current flows in both directions) to a Schottky (current flows one way) contact and back.
"We transferred electrons from the dopant-potassium-to the surface of the black phosphorus, which confined the electrons
and allowed us to manipulate this state. Potassium produces a strong electrical field which is required what we to tune the size of the band gap."
"This process of transferring electrons is known as doping and induced a giant Stark effect, which tuned the band gap allowing the valence
The conjecture is that this arises from an avalanche of electrons from the top surface of the film to the bottom,
where the electrons are confined near the substrate. This shift of electric charge occurs as the manganese atomic layers form atomically charged capacitors leading to the build up of an electric field, known as polar catastrophe
Of particular importance are new materials that conduct electricity by using missing electrons, otherwise known as"holes."
Although electron conducting (n-type) TCOS are presently in use in many devices, their hole-conducting (p-type) counterparts have not been commercialized as candidate materials
#Electrons that stick together, superconduct together The discovery of a surprising feature of superconductivity in an unconventional superconductor by a RIKEN-led research team provides clues about the superconducting mechanism in this material
Superconductivity occurs as the result of pairs of electrons binding together in such a way that they act as a single quasiparticle.
the binding force is provided by vibrations in the atomic lattice through which the electrons travel.
or spin fluctuation of the electrons themselves, which binds electrons in pairs through the entanglement of electron spins.
However recent experiments have shown that this mechanism cannot explain the superconducting state in the quintessential unconventional superconductor Cecu2si2.
Inspired by this result, Michi-To Suzuki and Ryotaro Arita from the RIKEN Center for Emergent Matter Science, in collaboration with Hiroaki Ikeda from Ritsumeikan University in Japan, investigated the mechanism of electron pairing in 2si2
The electrons in Cecu2si2 can interact by entanglement of both spin and orbital states, resulting in multiple possible configurations or degrees of freedom.
but to their surprise, the researchers found that multipole fluctuations can also produce bound pairs of electrons,
This kind of electron binding may also be present in the recently discovered class of high-temperature iron-based superconductors. e found that the origin of the unconventional superconductivity in Cecu2si2 is an exotic multipole degree of freedom consisting of entangled spins
and excel at transmitting electrons and heat. But when the two are joined, the way the atoms are arranged can influence all those properties. ome labs are actively trying to make these materials or measure properties like the strength of single nanotubes and graphene sheets,
#Physicists discover spiral vortex patterns from electron waves In their new study("Electron Vortices in Photoionization by Circularly Polarized Attosecond Pulses),
when an electron is ejected, or ionized, from its orbit around a helium atom. Like all subatomic particles, electrons occupy a realm governed by quantum mechanics.
This means that their position, velocity and other properties are probabilistic, existing within a range of possible values.
Electrons can also exhibit the behavior of waves that, like ripples in a pond often gain or lose amplitude as they cross paths.
By firing two time-delayed, ultrashort laser pulses at a helium atom, the researchers found that the distribution of momentum values for these intersecting electron waves can take the form of a two-armed vortex that resembles a spiral galaxy.
the team study is the first to produce the pattern with electrons. In doing so, it also dramatically demonstrates the wavelike property of matter,
Starace called the pattern an xcellent diagnostic toolfor characterizing electron-manipulating laser pulses which occur on such fast time scales that physicists have sought multiple ways to measure their durations and intensities.
whereas the duration of the pulses corresponds to the width of the arms. f you use (longer) pulses to probe the electrons,
in materials revealed by electron tomography")."For more than 100 years, researchers have inferred how atoms are arranged in three-dimensional space using a technique called X-ray crystallography,
which a beam of electrons smaller than the size of a hydrogen atom is scanned over a sample
and measures how many electrons interact with the atoms at each scan position. The method reveals the atomic structure of materials
because different arrangements of atoms cause electrons to interact in different ways. However scanning transmission electron microscopes only produce two-dimensional images.
The downside of this technique is repeated that the electron beam radiation can progressively damage the sample.
thanks to the electron beam energy being kept below the radiation damage threshold of tungsten. Miao and his team showed that the atoms in the tip of the tungsten sample were arranged in nine layers, the sixth
This produces almost no neutrons but instead fast, heavy electrons (muons), since it is based on nuclear reactions in ultra-dense heavy hydrogen (deuterium)."
"A considerable advantage of the fast heavy electrons produced by the new process is that these are charged
whereas the fast, heavy electrons are considerably less dangerous.""Neutrons are difficult to slow down or stop and require reactor enclosures that are several metres thick.
Muons-fast, heavy electrons-decay very quickly into ordinary electrons and similar particles. Research shows that far smaller and simpler fusion reactors can be built.
The scientists developed a nanoscale photodetector that uses the common material molybdenum disulfide to detect optical plasmons--travelling oscillations of electrons below the diffraction limit
rather than solely to the laser's wavelength, demonstrating that the plasmons effectively nudged the electrons in Mos2 into a different energy state."
and deposited metal contacts onto that same end with electron beam lithography. They then connected the device to equipment to control its bias,
the energy was converted into plasmons, a form of electromagnetic wave that travels through oscillations in electron density.
This energy electronically excited an electron once it reached the molybdenum disulfide-covered end effectively generating a current.
"We've morphed those silicon transistors into quantum bits by ensuring that each has only one electron associated with it.
We then store the binary code of 0 or 1 on the'spin'of the electron,
which is associated with the electron's tiny magnetic field, "he added. Dzurak noted that that the team had patented recently a design for a full-scale quantum computer chip that would allow for millions of our qubits,
#Physicists turn toward heat to study electron spin The quest to control and understand the intrinsic spin of electrons to advance nanoscale electronics is hampered by how hard it is to measure tiny, fast magnetic devices.
Applied physicists at Cornell offer a solution: using heat, instead of light, to measure magnetic systems at short length and time scales.
"Why the interest in electron spin? In physics, electron spin is established the well phenomenon of electrons behaving like a quantum version of a spinning top,
and the angular momentum of these little tops pointing por own. An emerging field called spintronics explores the idea of using electron spin to control
and store information using very low power. echnologies like nonvolatile magnetic memory could result with the broad understanding and application of electron spin.
Spintronics, the subject of the 2007 Nobel prize in Physics, is already impacting traditional electronics, which is based on the control of electron charge rather than spin. irect imaging is really hard to do,
Fuchs said. evices are tiny, and moving really fast, at gigahertz frequencies. Wee talking about nanometers and picoseconds.
When the electrons are travelling through a magnetic whirl, they feel the canting between the atomic magnets,
or high-energy reservoir of electrons. Lithium can do that, as the charge carrier whose ions migrate into the graphite
which requires transferring polarization from unpaired electrons to protons and then carbon nuclei, using microwaves generated by a gyrotron,
and electrons to read data Scientists from Kiel University and the Ruhr Universität Bochum (RUB) have developed a new way to store information that uses ions to save data
and electrons to read data. This could enable the size of storage cells to be reduced to atomic dimensions.
Standard memory devices are based on electrons which are displaced by applying voltage. The development of ever smaller and more energy-efficient storage devices according to this principle,
"Electrons are roughly 1000 times lighter than ions and so they move much more easily under the influence of an external voltage.
while the electrons remain mobile and can be used to read the storage status."The trick:
"The tunnel effect enables us to move electrons through the ultra-thin layer with very little energy,
and electrons, on the other hand, at voltages far below one volt. This way, ions can be used specifically for storing and electrons specifically for reading data.
The researchers also reported that their research had another very interesting element. The new resistance-based storage devices could even simulate brain structures.
which involves the gaining of electrons. The reduced-graphene oxide-coated materials were found to be particularly sensitive to detecting nitrogen dioxide
Overtext Web Module V3.0 Alpha
Copyright Semantic-Knowledge, 1994-2011