Discovery of a new physical phenomenon governed by a quantum law

Dec 19, 2005

A team of researchers has just discovered a new macroscopic physical phenomenon governed by a quantum law: quantum magnetic deflagration. The discovery, published in November in the American journal Physical Review Letters, was made by a team led by Javier Tejada, Professor of Fundamental Physics at the UB, and Paul Santos, a researcher at the Paul Drude Institute in Berlin.

Javier Tejada says that “to understand the idea a parallel could be drawn between chemical combustion and what we know as magnetic combustion. Combustion involves a reaction between a substance (the fuel) and a gas (the oxidizer), and a great amount of heat is released. In a complete combustion reaction the components of the material interact with the oxidizer to yield new components (burnt fuel). Deflagration is a combustion process produced by thermal conductivity and is propagated more slowly than the speed of sound. The simplest example is that of a piece of paper heated with a lighter at one end: one layer of paper burns and heats up the next layer until the whole piece of paper is burnt. That which is propagated and burnt is the flame, while what remains are the ashes”.

What, however, happens with a magnetic material? If we have a magnetic material with all the poles aligned in the same direction (for example, a material made of very small compasses, all of which have the north pole facing upwards) and we apply a magnetic field in the opposite direction the compass poles should turn slowly until, eventually, they are all aligned downwards. If we fire acoustic microwaves at the material to heat it up, then in a certain part of the material the heat will be sufficient to cause the compass poles to reverse in this area. This part of the material then heats the surrounding areas enough to produce the same reaction and the poles of other compasses are reversed; this propagation continues until all the spins are aligned downwards (the opposite of their initial orientation). The reversal of the poles is produced by the tunnelling effect of the magnetic moment, which is a quantum effect.

The researchers have discovered that the propagation speed at which the compass poles are reversed follows a law determined by quantum mechanics. In other words, and contrary to expectations, it is a macroscopic effect governed by a quantum law.

The discovery of quantum magnetic deflagration opens up a new experimental field of relevance to both basic science and technological applications. The article published in Physical Review Letters is the latest scientific advance to be derived from the discovery — ten years ago — of the spin tunnelling effect. The experiment was carried out in the UB under the leadership of Javier Tejada, Professor of Fundamental Physics, and Paul Santos, a researcher at the Paul Drude Institute in Berlin, with the collaboration of the lecturer Antonio García-Santiago, Alberto Hernàndez and Ferran Macià (doctoral students) and Joan Manel Hernàndez (Ramon y Cajal researcher) from the Department of Fundamental Physics at the UB. The research was funded by the company SAMCA, the Spanish Ministerio de Educación y Ciencia and the European Union, and was conducted using new generation equipment developed by the company Agilent Technology.

In addition to its impact in the research world the spin tunnelling effect discovered by J. R. Friedman, M. Sarachik, Javier Tejada and Ron Ziolo, and reported in Physical Review Letters in 1996, now features in text books on magnetism. Recognized as a scientific discovery by the editorials of prestigious journals (Science, Nature, Physics Today), this initial study on the discovery of the tunnelling effect has achieved one of the most significant citation indexes for publications from Physical Review Letters.

Source: Universidad de Barcelona

Explore further: 'Comb on a chip' powers new atomic clock design

add to favorites email to friend print save as pdf

Related Stories

Danish DNA could be key to happiness

10 minutes ago

(Phys.org) —Economists at the University's Centre for Competitive Advantage in the Global Economy (CAGE) have looked at why certain countries top the world happiness rankings. In particular they have found the closer a ...

What created this huge crater in Siberia?

20 minutes ago

What is it with Russia and explosive events of cosmic origins? The 1908 Tunguska Explosion, the Chelyabinsk bolide of February 2013, and now this: an enormous 80-meter wide crater discovered in the Yamal ...

Tokyo police make arrest in massive data leak case

20 minutes ago

Tokyo police said Thursday they had arrested an engineer for allegedly stealing massive amounts of personal data from an educational services firm, a leak that may ultimately affect more than 20 million people.

Recommended for you

'Comb on a chip' powers new atomic clock design

4 hours ago

Researchers from the National Institute of Standards and Technology (NIST) and California Institute of Technology (Caltech) have demonstrated a new design for an atomic clock that is based on a chip-scale ...

Quantum leap in lasers brightens future for quantum computing

4 hours ago

Dartmouth scientists and their colleagues have devised a breakthrough laser that uses a single artificial atom to generate and emit particles of light. The laser may play a crucial role in the development of quantum computers, ...

Technique simplifies the creation of high-tech crystals

4 hours ago

Highly purified crystals that split light with uncanny precision are key parts of high-powered lenses, specialized optics and, potentially, computers that manipulate light instead of electricity. But producing ...

A new multi-bit 'spin' for MRAM storage

7 hours ago

Interest in magnetic random access memory (MRAM) is escalating, thanks to demand for fast, low-cost, nonvolatile, low-consumption, secure memory devices. MRAM, which relies on manipulating the magnetization ...

User comments : 0