Magnetism - Page 3

Scientists from St. Petersburg University and Tomsk University in Russia, along with teams at the Max Planck Institute in Germany and University of the Basque Country, Spain, have modified graphene in such a way that it has taken the properties of cobalt and gold: magnetism and spinorbit interaction. This advance can greatly benefit quantum computers.

The graphene was (for the first time, according to the researchers) modified to adopt such fundamental properties as magnetism and spin-orbit interaction. The spin of an electron is a magnet induced by the spin of the electron around its axis. It also orbits the nucleus to produce electric current and therefore a magnetic field. The interaction between the magnet and magnetic field is a spin-orbit interaction. Unlike in gold, the spin-orbit interaction in graphene is extremely small. The interaction between graphene and gold increase spin-orbit interaction in graphene, while interaction between graphene and cobalt induces magnetism, the team explained.

Researchers from the Lawrence Berkeley National Laboratory discovered the world's first magnetic 2D material - chromium germanium telluride (CGT). It was debatable whether magnetism could survive in such thin materials - and this discovery could pave the way to extremely thin spintronics devices.

The CGT flakes were produced using the scotch-tape method - the same one used to produce graphene for the first time in Manchester in 2004.

Researchers at the Czech Republic created magnetized carbon by treating graphene layers with non-metallic elements, said to be the first non-metal magnet to maintain its magnetic properties at room temperature. The researchers say such magnetic graphene-based materials have potential applications in the fields of spintronics, biomedicine and electronics.

By treating graphene with other non-metallic elements such as fluorine, hydrogen, and oxygen, the scientists were able to create a new source of magnetic moments that communicate with each other even at room temperature. This discovery is seen as "a huge advancement in the capabilities of organic magnets".

A study at TIFR (Tata Institute of Fundamental Research) designed a system that allows electronic interactions to be observed in three layers of graphene. The study reveals a new kind of magnet and provides insight on how electronic devices using graphene could be made for fundamental studies as well as applications, shedding light on the magnetism of electrons in three layers of graphene at a low temperature of -272 Celsius that arises from the coordinated "whispers" between many electrons.

Metals have a large density of electrons, so being able to see the wave nature of electrons requires making metallic wires a few atoms wide. However, in graphene the density of electrons is much smaller and can be changed by making a transistor. As a result, the wave nature of electrons is easier to observe in graphene.

Saint Jean Carbon, a carbon science company engaged in the design and development of carbon materials and their applications, recently received (along with Western University) a grant from the The Natural Sciences and Engineering Research Council of Canada (NSERC) towards the development of graphene-based systems with special magnetic properties.

The $100,000 grant will be used to cover the cost of the lab work, testing, material creation and all research associated costs. The company stated that it aims to use the funds to get beyond the lab and into working prototypes, scaled models and future commercial production. In addition, SJC hopes that "the results will play a big role in the medical field as well in energy storage for electric cars and green energy creation".

Saint Jean Carbon, a carbon science company engaged in the exploration of natural graphite properties and related carbon products, has teamed up with the University of Western Ontario to create graphene that has a magnetic field (Magnetoresistance).

One of the involved researchers explained that: "Magnetoresistance (MR) refers to the significant change of electrical resistance of materials under a magnetic field. Magnetoresistance effects have been applied in magnetic sensors, spintronic devices and data storage. Magnetic sensors are extremely useful for today's industry for measurement and control purposes... This happens by detecting changes in electrical resistance brought on by the presence of a magnetic field. This is also known as magnetoresistance (MR). The market size of the magnetic sensor is increasing with annual growth rate at 10% because of new nanomaterials..."

Researchers at the Autonomous University of Madrid, in collaboration with CIC nanoGUNE and the Institut Néel of Grenoble, have demonstrated that the simple absorption of a hydrogen atom on a layer of graphene magnetizes a large region of it. As a result, by selectively manipulating these hydrogen atoms, it is possible to produce magnetic graphene with atomic precision.

Graphene inherently lacks magnetic properties. The hydrogen atom has the smallest magnetic moment (the magnitude that determines how much and in what direction a magnet will exert force). This work reveals how when a hydrogen atom touches a graphene layer it transfers its magnetic moment to it. The researchers explain that in contraposition to more common magnetic materials such as iron, nickel or cobalt, in which the magnetic moment generated by each atom is located within a few tenths of a nanometre, the magnetic moment induced in the graphene by each atom of hydrogen extends several nanometres, and likewise displays a modulation on an atomic scale.

Researchers at Joseph Fourier University in Grenoble, France, have found that coating a cobalt film in graphene could double the film's perpendicular magnetic anisotropy (PMA), so that it reaches a value 20 times higher than that of traditional metallic cobalt/platinum multilayers that are being researched for this property. In a material with a high PMA, the magnetization is oriented perpendicular to the interface of the material's layers. High-PMA materials are being researched for their applications in next-generation spintronic devices, such as high-density memories and heat-tolerant logic gates. 

A major goal in developing spintronic devices is to reduce the size of the devices while achieving long-term information retention of 10-plus years. In order to do this, the storage material must have a large PMA. Enhancement of effective PMA could be achieved either by increasing the surface PMA or by minimizing the saturation magnetization of the storage layer. These co-graphene heterostructures benefit from both these properties. The PMA enhancement in the graphene-coated cobalt films originates at the atomic level, where graphene affects the energy of cobalt's different electron orbitals. The graphene coating changes how these orbitals overlap with one another, which in turn changes the direction of the cobalt film's overall magnetic field: some of the magnetization that was originally parallel to the film surface is now oriented perpendicular to the film surface.

Researchers at the University of Maryland, along with collaborators from the National Institute of Standards and Technology (NIST), have developed a theoretical model that demonstrates how to shape and stretch graphene to create a powerful, adjustable and sustainable magnetic force. This discovery could also be a major step in understanding how electrons move in extremely high magnetic fields.

Graphene's electrons react to stretching or straining by behaving as if they are in a strong magnetic field. This so-called pseudomagnetic effect could open up new possibilities in graphene electronics, but so far, researchers have only been able to induce limited pseudofields that are far from to realizing in practice. However, Maryland researchers may have explained how to shape a graphene ribbon so that simply pulling its two ends produces a uniform pseudomagnetic field.The team is confident that they will soon be able to transition their theoretical model to a design reality.

Researchers from the National University of Singapore (NUS) have developed a hybrid magnetic sensor that is reportedly more sensitive than most commercially available sensors. This could encourage the development of smaller and cheaper sensors for areas like consumer electronics, information and communication technology and automotive, as well as applications like thermal switches, hard drives and magnetic field sensors.

The sensor is made of graphene and boron nitride, and includes layers of carrier-moving channels, each of which can be controlled by the magnetic field. The researchers characterized the sensor by testing it at various temperatures, angles of magnetic field, and with a different pairing material. Graphene-based magnetoresistance sensors hold immense promise over existing sensors due to their stable performance over temperature variation and eliminating the necessity for expensive wafers or temperature correction circuitry. Production cost for graphene is also much lower than silicon and indium antimonide.