2014-05-07 21:41:34
A magnet is an amazing, almost magical artifact. Although we are familiar with forces that exert their power at a distance, gravity is a good example of this, a magnet seems to have a special attraction, because it affects some substances and not others. Their influence on the bodies around them, a power we call the magnetic field, allows them to achieve surprising feats, such as making a pin dance without touching it, extracting iron shavings from the sand, setting the course using a compass, or recording information on the body. hard drive of our computer.
Although most common magnets are the size of everyday objects, the power of magnetism is shown on every scale imaginable. Galaxies, including our own, the Milky Way, are surrounded by magnetic fields whose detection has just been published. Stars, like the Sun, generate changing magnetic fields that send powerful flares of particles into space. The Earth protects us with its magnetic envelope from the harmful particles emitted by the Sun and helps us orient ourselves thanks to the compass. On a smaller scale, magnets abound in household appliances, they are essential to make the motor of your refrigerator or blender work, they exert their silent action in a multitude of places, such as the soft closure of the mobile phone case, or the decorations plans that hold the notes to the refrigerator door. Beyond what our eyes can see, there are magnets hidden in countless sensors and electronic devices that make our lives easier and safer.
When we really want to understand how magnetism works, we have to go down to the most intimate part of matter, to the atoms and electrons. Basically, all magnetic materials are composed of tiny “atomic magnets” that associate with each other, strengthening or weakening each other. The different degree of association between them gives rise to materials that have very different behavior against magnetism. Thus we talk about paramagnetic, ferromagnetic, antiferromagnetic, superparamagnetic materials or spin glasses. Materials that Mr. José Ángel de Toro Sánchez, researcher at the Magnetic Materials Group of the Regional Institute for Applied Scientific Research from Castilla-La Mancha university.
With these little atomic magnets, the Magnetic Materials Group in which today’s guest researches, studies the properties of tiny magnetic nanoparticles that find application in many fields, from computing to biomedicine.
Magnetic nanoparticles have implications for the magnetic storage that takes place on computer hard drives. The physical limit imposed by downscaling is conditioned by the so-called “superparamagnetic limit” that marks a barrier below which it is not possible to store information without it being spontaneously erased. The objective of the research is to “delay” the arrival of this physical limit of the technology, so that a greater reduction in scale and, therefore, greater storage capacity is achieved. The strategy to achieve this objective is based on exploiting the phenomenon known as “anisotropic exchange” or “exchange bias” to increase the magnetic stability of the nanoparticles. This phenomenon has already been exploited industrially for a few years in another important technology: the magnetization sensor of the reading heads of the hard drives themselves (spin valves), whose operation is based on the giant magnetoresistance (GMR) effect, the discovery of which Albert Fert received the Nobel Prize in 2007. In addition, the group studies the magnetic behavior of “superglasses” and “supercrystals”, where the prefix “super” indicates the replacement of atoms by nanoparticles in the respective amorphous or crystalline (ordered) systems.
In biomedicine, magnetic nanoparticles have applications in the treatment of certain tumors. Among the possible uses of these tiny particles is to use them as tiny guided missiles against the tumor. Nanoparticles can be injected into a patient and guided to tumors by applying external magnetic fields. Once there, these external magnetic fields can achieve a temperature increase that kills cancer cells and spares normal ones.
We invite you to listen to Mr. José Ángel de Toro Sánchez, researcher in the Magnetic Materials Group of the Regional Institute of Applied Scientific Research of the University of Castilla la Mancha.
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Regional Institute for Applied Scientific Research
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