Heated magnetic nanoparticles may be the future of eradicating cancer cells without harming healthy tissue, according to research from the University of Buffalo, USA. The nanoparticles strike tumours with significant heat under a low magnetic field.
Hao Zeng, Professor of Physics at Buffalo, said, ‘The main accomplishment of our work is the greatly enhanced heating performance of nanoparticles under low-field conditions suitable for clinical applications. The best heating power we obtained is close to the theoretical limit, greatly surpassing some of the best performing particles that other research teams have produced.’
Targeting technologies would first direct nanoparticles to tumours within the patient’s body. Exposure to an alternating magnetic field would prompt the particles’ magnetic orientation to flip back and forth hundreds of thousands of times a second, causing them to warm up as they absorb energy from the electromagnetic field and convert it to thermal energy.
Two particles have been tested – manganese-cobalt-ferrite and zinc ferrite. While the manganese particle reached maximum heating power under high magnetic fields, the biocompatible zinc ferrite was efficieny under an ultra-low field.
While this form of treatment, known as magnetic nanoparticle hyperthermia, is not new, the Buffalo-designed particles are able to generate heat several times faster than the current standard.
Typically research has focused on the effects induced by different materials in graphene. Convinced that this is only half the story, Dr Zeila Zanolli turned the tables to look at the proximity effects of graphene on magnetic semiconducting substrates. Using first principles calculations she observes a switching of internal spin alignment from antiferromagnetic to ferromagnetic. Persisting close to room temperature, her findings could find applications in magnetic memories or spin filters.
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In a refreshing change of perspective, theoretical physicist Dr Zeila Zanolli has looked at the proximity effects of graphene on a magnetic semiconducting substrate, finding it to affect the substrate’s magnetism down to several layers below the surface. Her paper was published on 5 October in Physical Review B. She was also one of three recipients of the first MaX Prize for frontier research in computational materials science.
Topological spin textures in magnetic systems are intriguing objects that exhibit exotic physics and have potential applications in information storage and processing. The most fundamental and exemplary topological spin texture is called the skyrmion, which is a nanoscale circular domain wall carrying a nonzero integer topological charge. The skyrmion texture in magnetic materials was theoretically predicted in the late 1980s, and it was experimentally observed in chiral magnets a decade ago. Since the first observation of magnetic skyrmions, the skyrmion community has focused on a series of topological spin textures evolved from the skyrmion, such as the skyrmionium and bimeron.
In a recent theoretical work carried out by an international team from China, Japan, Australia, Russia, and France. The authors introduced a new type of topological spin textures, which is called the bimeronium. The bimeronium exists in magnets with in-plane magnetization. It is a topological counterpart of skyrmionium in perpendicularly magnetized magnets and can be seen as a combination of two bimerons with opposite topological charges. Therefore, the bimeronium carries a topological charge of zero, like the skyrmionium.
When two sheets of the carbon nanomaterial graphene are stacked together at a particular angle with respect to each other, it gives rise to some fascinating physics. For instance, when this so-called “magic-angle graphene” is cooled to near absolute zero, it suddenly becomes a superconductor, meaning it conducts electricity with zero resistance.
Now, a research team from Brown University has found a surprising new phenomenon that can arise in magic-angle graphene. In research published in the journal Science, the team showed that by inducing a phenomenon known as spin-orbit coupling, magic-angle graphene becomes a powerful ferromagnet.
“Magnetism and superconductivity are usually at opposite ends of the spectrum in condensed matter physics, and it’s rare for them to appear in the same material platform,” said Jia Li, an assistant professor of physics at Brown and senior author of the research. “Yet we’ve shown that we can create magnetism in a system that originally hosts superconductivity. This gives us a new way to study the interplay between superconductivity and magnetism, and provides exciting new possibilities for quantum science research.”
Scientists shed light on how the magnetic properties of 2D interlayers can enhance spin accumulation effects in thermoelectric heterostructures.
Spin thermoelectric materials are an area of active research because of their potential applications in thermal energy harvesters. However, the physics underlying the effects of interlayers in these materials on spin transport phenomena are unclear. In a recent study, scientists from Chung-Ang University, Korea, shed light on this topic using a newly developed platform to measure the spin Seebeck effect. Their findings pave the way to large-area thermoelectric materials with enhanced properties.
Thermoelectric materials, which can generate an electric voltage in the presence of a temperature difference, are currently an area of intense research; thermoelectric energy harvesting technology is among our best shots at greatly reducing the use of fossil fuels and helping prevent a worldwide energy crisis. However, there are various types of thermoelectric mechanisms, some of which are less understood despite recent efforts. A recent study from scientists in Korea aims to fill one such gap in knowledge. Read on to understand how!
Current silicon-based computing technology is energy-inefficient. Information and communications technology is projected to use over 20% of global electricity production by 2030. So finding ways to decarbonise technology is an obvious target for energy savings. Professor Paolo Radaelli from Oxford’s Department of Physics, working with Diamond Light Source, the U.K.“s national synchrotron, has been leading research into more efficient alternatives to silicon. His group’s surprising findings are published in Nature in an article titled "Antiferromagnetic half-skyrmions and bimerons at room temperature.” Some of the antiferromagnetic textures they have found could emerge as prime candidates for low-energy antiferromagnetic spintronics at room temperature.
Researchers have been working for a long time on alternative technologies to silicon. Oxides of common metals such as iron and copper are natural targets because they are already a technology staple, present in silicon-based computers, meaning there is a high chance of compatibility between the two technologies. Although oxides are great for storing information, they are not good at moving information around—a necessity for computation. However, one property of oxides that has emerged is that many are magnetic, which means it might be possible to move magnetic bits around, both in oxides and in other magnets, with very little energy required.
An international team of researchers, affiliated UNIST has introduced an exiting new organic network structure that shows pure organic ferromagnetic property at room temperature. As described in the CHEM journal this pure organic material exhibits ferromagnetism from pure p-TCNQ without any metal contamination.
This breakthrough has been led by by Professor Jong-Beom Baek and his research team in the School of the Energy and Chemical Engineering at UNIST. In the study, the research team has synthesized a network structure from the self polymerization of tetracyanoquinodimethane (TCNQ) monomer. The designed organic network structure generates stable neutral radicals.
For over two decades, there has been widespread scepticism around claims of organic plastic ferromagnetism, mostly due to contamination by transition metals. Extensive effort has been devoted to developing magnets in purely organic compounds based on free radicals, driven by both scientific curiosity and the potential applications of a ‘plastic magnet’. Excluding the contamination issues and realizing magnetic properties from pure organic plastics must occur to revive the quest for plastic magnetism.
Scientists have succeeded in observing the first long-distance transfer of information in a magnetic group of materials known as antiferromagnets. These materials make it possible to achieve computing speeds much faster than existing devices. Conventional devices using current technologies have the unwelcome side effect of getting hot and being limited in speed. This is slowing down the progress of information technology.
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The emerging field of magnon spintronics aims to use insulating magnets capable of carrying magnetic waves, known as magnons, to help solve these problems. Magnon waves are able to carry information without the disadvantage of the production of excess heat. Physicists at Johannes Gutenberg University Mainz (JGU) in Germany, in cooperation with theorists from Utrecht University in the Netherlands and the Center for Quantum Spintronics (QuSpin) at the Norwegian University of Science and Technology (NTNU) in Norway, demonstrated that antiferromagnetic iron oxide, which is the main component of rust, is a cheap and promising material to transport information with low excess heating at increased speeds. Their study has been published recently in the scientific journal Nature.
Sophisticated features may influence eventual Z-machine rebuild
A new Sandia National Laboratories accelerator called Thor is expected to be 40 times more efficient than Sandia’s Z machine, the world’s largest and most powerful pulsed-power accelerator, in generating pressures to study materials under extreme conditions.
“Thor’s magnetic field will reach about one million atmospheres, about the pressures at Earth’s core,” said David Reisman, lead theoretical physicist of the project.
Though unable to match Z’s 5 million atmospheres, the completed Thor will be smaller – 2,000 rather than 10,000 square feet – and will be considerably more efficient due to design improvements that use hundreds of small capacitors instead of Z’s few large ones.
Remarkable structural transformation
This change resembles the transformation of computer architecture in which a single extremely powerful computer chip was replaced with many relatively simple chips working in unison, or to the evolution from several high-voltage vacuum tubes to computers powered by a much larger number of low-voltage solid-state switches.
On an otherwise normal day in the lab, Eva Andrei didn’t expect to make a major discovery. Andrei, a physics professor at Rutgers University, was using graphite – the material in pencils – to calibrate a scanning tunneling microscope. As part of the process, she turned on a very powerful magnetic field. When she looked up to see the material’s electronic spectrum, she was astonished. “We saw huge, beautiful peaks up there, just incredible. And they didn’t make any sense,” she recalled.
Remembering a lecture she’d recently attended, she realized the graphite had separated out into sheets just one atom thick. This material, known as graphene, has bizarre electronic properties. But even for graphene, the spectrum she saw was strange. In fact, no one had ever seen anything like it before. As Andrei described it, her colleague “went berserk in the corridor and just yelled ‘Graphene!’” Andrei had made a serendipitous discovery – a new electric phenomenon.
This was neither the first nor last time that electrons’ movement in graphene would surprise and elate scientists. One of the most impressive things about graphene is how fast electrons move through it. They travel through it more than 100 times faster than they do through the silicon used to make computer chips. In theory, this suggests that manufacturers could use graphene to make superfast transistors for faster, thinner, more powerful touch-screens, electronics, and solar cells.
Scientists at the U.S. Department of Energy’s Ames Laboratory were able to successfully manipulate the electronic structure of graphene, which may enable the fabrication of graphene transistors— faster and more reliable than existing silicon-based transistors.
The researchers were able to theoretically calculate the mechanism by which graphene’s electronic band structure could be modified with metal atoms. The work will guide experimentally the use of the effect in layers of graphene with rare-earth metal ions “sandwiched” (or intercalated) between graphene and its silicon carbide substrate. Because the metal atoms are magnetic the additions can also modify the use of graphene for spintronics.
“We are discovering new and more useful versions of graphene,” said Ames Laboratory senior scientist Michael C. Tringides. “We found that the placement of the rare earth metals below graphene, and precisely where they are located, in the layers between graphene and its substrate, is critical to manipulating the bands and tune the band gap.”
Researchers at the Department of Energy’s Oak Ridge National Laboratory have developed a new method to manipulate a wide range of materials and their behavior using only a handful of helium ions.
The team’s technique, published in Physical Review Letters, advances the understanding and use of complex oxide materials that boast unusual properties such as superconductivity and colossal magnetoresistance but are notoriously difficult to control.
For the first time, ORNL researchers have discovered a simple way to control the elongation of a crystalline material along a single direction without changing the length along the other directions or damaging the crystalline structure. This is accomplished by adding a few helium ions into a complex oxide material and provides a never before possible level of control over magnetic and electronic properties.
“By putting a little helium into the material, we’re able to control strain along a single axis,” said ORNL’s Zac Ward, who led the team’s study. “This type of control wasn’t possible before, and it allows you to tune material properties with a finesse that we haven’t previously had access to.”
Despite their ubiquity in consumer electronics, rare-earth metals are, as their name suggests, hard to come by. Mining and purifying them is an expensive, labor-intensive and ecologically devastating process. Starting with the two elements as a mixed powder, a metal-binding molecule known as a…
Scientists have long thought that plutonium should be magnetic but observing that property experimentally seemed impossible. Now, a neutron scattering study by researchers in the USA has revealed that this electronically complex and unstable heavy metal does indeed display magnetism, but it is in constant flux, hence the difficulties in attempting to observe it since the metal was first produced 75 years ago.
Plutonium famously is a fissile material and was first produced in 1940 by Glenn Seaborg and Edwin McMillan at the University of California, Berkeley, by bombarding uranium-238 with deuterons. Not only is it radioactive, but its 5f electrons sit in a state between delocalized and localized and the energy difference between this shell and the 6d shell is very low, which gives rise to anomalous chemical behavior. Theories abound as to why plutonium should have such a complex electronic structure and predict that the metal should have magnetic order.
Marc Janoschek and colleagues at Los Alamos and at Oak Ridge national laboratories have detected the ever-changing magnetism of plutonium. Plutonium exists in a state of quantum mechanical superposition, Janoschek explains, in which the electrons are completely localized in one state giving rise to a magnetic moment and at the other extreme are entirely delocalized and no longer associated with the same ion in the bulk.
Scientists pursuing better performance in a well-known type of iron-based magnet also discovered wide-gap semiconducting behavior and a quantum state useful for quantum information processing—all in a single low-cost material that has been in existence for decades.
Scientists at the U.S. Department of Energy’s Critical Materials Institute, or CMI, study ways to make lower-cost, easier-to-obtain materials used as ingredients in technologies that are in demand now or are developing for the future. In this case, the researchers were investigating ways to create a stronger iron-based permanent magnet, something referred to as a “gap” magnet.
Permanent magnets fall into two broad categories. The strongest-performing permanent magnetscontainrare-earth metals like samarium, neodymium, and dysprosium—their properties make them the best and often only choice for applications like computer hard disk drives and motors in hybrid and electric vehicles. These magnets are typically expensive, and their rare-earth components can be difficult to obtain. The second, iron-based permanent magnets, are inexpensive and made of readily available materials, but their performance is often too poor for many advanced applications. In between the high performing rare-earth magnets and low-performing iron-based magnets is a “gap,” where there is a great need for permanent magnets that perform in the mid-range of desirable properties. Filling that gap reduces the need for rare-earth magnets, and in turn hard to source rare-earth materials.
Fujitsu Limited today announced that, in joint research with the National Institute for Materials Science (NIMS) and Fujitsu Laboratories Ltd., it has developed the world’s largest magnetic-reversal simulator, using a mesh covering more than 300 million micro-regions.
Based on the large-scale magnetic-reversal simulation technology first developed in 2013, this new development offers a faster calculation algorithm and more efficient massive parallel processing. The simulations are run on the K computer. In addition, by utilizing this technology, Fujitsu conducted large-scale simulations to clarify the correlation between the fine structure of neodymium magnets, a type of permanent magnet, and magnetic strength, by examining the process of magnetic reversal in neodymium magnets. The results successfully demonstrated a way to develop high-strength neodymium magnets with more than twice the coercivity of previous magnets, without dysprosium. In conventional neodymium magnets, dysprosium alloying is indispensable for enhancing magnetic coercivity. These simulation techniques offer a clear design rule for high-performance neodymium magnets that do not rely on dysprosium. Fujitsu and NIMS will be making a joint presentation on these results at the 13th Joint MMM-Intermag Conference, running January 11-15, 2016, in San Diego, California.
Energy-harvesting magnets that change their volume when placed in a magnetic field have been discovered by US researchers. The materials described by Harsh Deep Chopra of Temple University and Manfred Wuttig of the University of Maryland produce negligible waste heat in the process and could displace current technologies and lead to new ones, such as omnidirectional actuators for mechanical devices and microelectromechanical systems (MEMS). [Nature, 2015, 521, 340-343; DOI:10.1038/nature14459]
All magnets change their shape but not their volume, even auxetic magnets were previously characterized on the basis of volume conserving Joule magnetostriction. This fundamental principle of volume conservation has remained unchanged for 175 years, since the 1840s, when physicist James Prescott Joule found that iron-based magnetic materials would elongate and constrict anisotropically but not change their volume when placed in a magnetic field, so-called Joule magnetostriction.
The work of Chopra, Wuttig changes that observation fundamentally with the demonstration of volume-expanding magnetism. “Our findings fundamentally change the way we think about a certain type of magnetism that has been in place since 1841,” explains Chopra. “We have discovered a new class of magnets, which we call ‘Non-Joulian Magnets,’ that show a large volume change in magnetic fields.” Chopra described the phenomenon to us: “When ‘excited’ by a magnetic field, they swell up like a puffer fish,” he says.
The electron is a first generation fermionand a lepton. Fermions are particles with have half-integer spinthat follow Fermi-Dirac statistics and obey the Pauli exclusion principle. The Pauli exclusion principle states that two identical fermions can’t occupy the same quantum state (i.e. have the same quantum numbers within a quantum system). Leptons are a subcategory within fermions that can exist independently (without binding together) and do not interact through the strong force unlike quarks. Lastly the generations of the fermions loosely refers to the higher masses for particles in higher generations.
The existence of electrons was first discovered by J.J. Thompson in 1897 when he experimented with cathode ray tubes like the one depicted above. By applying electric and magnetic fields across the cathode ray Thompson was able to determine the mass-to-charge ratio of the particles in the cathode ray. With this he found that the particles were much smaller than any atom and by testing different sources, these negatively charged particles exist in every element.
Electrons are one of the primary charge carriers in atoms alongside protons but are the primary contributors to electric current. Electrons also have an intrinsic property known as spin which contributes to paramagnetismin certain materials.
Above is a video of an electron riding a light wave. The video was taken using a stroboscope which captures. More on it here (article)andhere (video).
Research involving electrons covers almost every corner of modern physics from high energy particle physics to condensed matter physics and even quantum computing. I have linked articles on recent research with a focus on electrons below for further reading.
As someone who used to play the bass guitar, I can’t believe I didn’t know how a guitarpickup works. The basic idea is actually relatively simple but the complexity comes when engineering the sound we hear from Jimi Hendrix, Jimmy Page, and B.B. King.
The mechanism is centered around Faraday’s Law of Induction. The guitar pickup in its simplest form is a permanent magnet(s) wrapped in a coil of wire. A permanent magnet is made from a ferromagnetic material (like iron) which is a special type of material where the “magnetic domains” are aligned with an external applied magnetic field.
The role of the permanent magnet is to magnetize the guitar string because it is also a ferromagnetic material like nickel or steel. When you pluck the string it vibrates and results in an oscillating(changing)magnetic flux through the coil. Because of Faraday’s Law of Induction this induces a signal(changing voltage) and thus current which is read by the amp to reverse engineer it into sound. Check out thisappletfrom the National High Magnetic Field Laboratory for a visual.
Since the string’s movement determines the signal picked up, the pickups receive a strong signal when directly under a part of the string moving with a large amplitude and frequency. So when it is directly under a node(where the string doesn’t move) like in the above picture (for the 7th harmonic), one of the pickups gets a very weak or possibly no signal. So in a way the pickups act as filtersfor the different harmonics depending on their placements which is key to the sounds we hear in the music. So as you can see the exact engineering can become extremely complicated
