Magnetic Fire Reveals Energy's Path
May 14, 2013

Research Reveals How Energy Is Released And Dispersed In Magnetic Materials

John P. Millis, Ph.D. for — Your Universe Online

The most efficient ways of storing energy is within electric and magnetic fields. And as the world proceeds to develop ever more efficient and “green” energy solutions, understanding the nature of these fields and how the energy propagates is essential.

One of the challenges is understanding how energy flows through magnetic materials. Researchers have been trying for decades to draw a parallel between the flow of thermal or chemical reactions to that of magnetic energy flows.

For instance, in the case of thermal energy transfer, an initial spark can create a flame. As that flame heats material — say, the trunk of a tree — the material begins to burn. The energy given off by the burning process heats the surrounding area, allowing the fire to spread.

Similarly, in chemical reactions a minimum energy level, known as the activation energy, is required to ignite the chemical reaction. The reaction proceeds depending on the specific chemical components in question. Because of this dependence the reaction cannot easily be varied.

By contrast, magnetic materials and the very fields themselves can manipulate the release and flow of energy. The result is that the system could be controlled.

In order to investigate this, researchers drew from chemical systems and realized if they could create a “spark”, they could induce the spread of magnetic energy — known as magnetic fire.

The investigators realized they could create such a spark using crystalline molecules that, when heated, would spin and produce a magnetic field. As heat was applied, the spin direction of the molecules would flip, causing energy to be transferred to nearby material.

"When the molecules' spins are aligned opposite the applied field direction, they possess a high level of energy," according to Andrew Kent, professor of physics at NYU and the study's senior researcher. "And then when the spins 'flip,' energy is released and dispersed into surrounding magnetic material that can cause a runaway reaction."

Unlike chemical reactions which are dependent on the chemical constituents, the evolution of the energy transfer in these systems could be controlled through the applied magnetic field.

"These are exciting results and ones that have prompted us to further consider whether a spark is even necessary to start a magnetic fire," added Kent. "We hope to observe and study situations in which the fire starts spontaneously, without a spark."

The study appears in the journal Physical Review Letters and also included researchers from the University of Barcelona, City College of New York and the University of Florida.