Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The mesoscopic tunnelling of magnetization: A historic milestone in twentieth-century science

09.12.2008
The tunnel effect of magnetization, a highly unusual property of the world of quantum mechanics discovered by the Magnetism Group of the Department of Fundamental Physics at the University of Barcelona (UB), led by Professor Javier Tejada (Castejón, 1948), in cooperation with groups from the City University of New York and the firm Xerox, has been acknowledged as one of the milestones in the study of spin of the twentieth century in the special collection Milestones in Spin, published by the leading scientific journal Nature.

This is the first time that a Spanish physicist has received credit in this country as the discoverer of a new physical phenomenon: the mesoscopic tunnelling of magnetization in molecular magnets (Physical Review Letters, 1996). This scientific breakthrough has now made its way into textbooks on magnetism.

It explains how the magnetic poles of small magnets, formed by millions of atoms, at very low temperatures, can change orientation due to the tunnel effect and without any energy expenditure. Now, the journal Nature has recognized this discovery as a historic milestone in the science of spin (the property of elementary particles to rotate around their axis in relation to their magnetic field).

Milestones in Spin also records the contributions of great figures in the world of physics, such as Nobel Prize winners Albert Einstein (1921); Paul A. M. Dirac (1933); Otto Stern (1943); Felix Bloch and E. M. Purcell (1952), Douglas Osheroff, Robert Richardson and David Lee (1996); Frank Wilczek, David Gross and David Politzer (2004), and Albert Fert and Peter Grünberg (2007).

The uncertainty principle governs the world of quantum physics: it is impossible to know the position and the momentum of an object at the same time. This is a property of quantum objects and does not depend on the ability to make an exact measurement. This uncertainty, at macroscopic scale, cannot be detected experimentally, and this has generated intense scientific debate in the frontiers of quantum physics and in the mesoscopic world. For the researchers, the tunnel effect is an unexpected consequence of quantum mechanics, and the magnets of mesoscopic size are the best systems for detecting quantum tunnelling phenomena.

The collection Milestones in Spin highlights 23 historic events in the study of spin, from the discovery of the first physical phenomenon in this field (the Zeeman effect, 1896) until the present day. Milestone 22, entitled «Mesoscopic tunneling of magnetization» is the quantum tunnel effect in magnetic poles, a phenomenon discovered by Javier Tejada, J. R. Friedman, M. Sarachik and Ron Ziolo and described in the article «Macroscopic measurement of resonant magnetization tunneling in high-spin molecules» (Physical Review Letters, 1996).

In this study, the scientists showed that the reorientation of the magnetic poles of mesoscopic sized magnets occurs due to quantum tunnelling, a curious property of the quantum world according to which an elementary particle can disappear and reappear outside the space in which it is confined.

In accordance with the theories of the physicist Eugene Chudnovsky on the tunnel effect, Tejada and his co-workers study the magnetism of mesoscopic magnets, and have discovered new fundamental laws of quantum phenomena in magnetism: the first experimental evidence of the tunnel effect of magnetization (1992), the resonant spin tunnelling (1996), quantum spin coherence (1999) and quantum magnetic deflagration (2005). Science, Nature, and Physics Today are some of the international journals that reported the new physical effect, discovered in 1996 by the research team at the UB and in the United States.

In the area of spin physics, the article «Field tuning of thermally activated magnetic quantum tunnelling in Mn12-Ac molecules», was the second to report evidence of the tunnel effect using an independent technique, published in the journal Europhysics Letters (1996), by the researchers Javier Tejada, Joan Manel Hernàndez and X. X. Zhang of the Department of Fundamental Physics at the UB, in conjunction with F. Luis and J. Bartolomé of the Materials Science Institute of Aragon and Ron Ziolo of the Xerox Corporation in New York.

The expectations raised by resonant spin tunnelling in the field of applied and basic physics open up new frontiers for the study of new macroscopic quantum phenomena and the testing of theories.

Winner of the Principe de Viana Prize for Culture in 2006, and recipient of an honorary doctorate from the City University of New York in 1996, Javier Tejada is a renowned expert in the field of magnetism and in the study of quantum effects in magnetism and superconductivity using microwaves and acoustic waves as high frequency. Professor of the Department of Fundamental Physics, he is the director of the UBX and the Magnetism Group at the UB, and is a member of the Spanish Royal Society of Physics, the Catalan Society of Physics, the New York Academy of Sciences and the American Physical Society.

Javier Tejada is the author of more than 280 scientific studies in leading journals such as Science, Physical Review Letters, Physical Review B, Europhysics Letters, Applied Physics Letters and Nature Materials. Tejada, who holds fifteen international patents in cooperation with firms and institutions, has been admitted as a Fellow of the American Physical Society (2000), and has received the Narcis Monturiol Medal from the Catalan government (1994), the International Award of the Xerox Foundation (1998) and the Catalan government distinction for the Promotion of University Research (2001).

Rosa Martínez | alfa
Further information:
http://www.ub.edu

More articles from Physics and Astronomy:

nachricht New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>