Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Superconductivity can induce magnetism

15.09.2008
Results clearly indicate that superconductivity is a condition required to establish this magnetic order

When an electrical current passes through a wire it emanates heat – a principle that's found in toasters and incandescent light bulbs. Some materials, at low temperatures, violate this law and carry current without any heat loss. But this seemingly trivial property, superconductivity, is now at the forefront of our understanding of physics.

In the September 11 edition of the prestigious journal Science, Andrea Bianchi, a professor in the Department of Physics at the Université de Montréal, and his colleagues show that, contrary to previous belief, superconductivity can induce magnetism, which has raised a new quantum conundrum.

Using the Swiss spallation neutron source (SINQ) of the Paul-Scherrer Institute (PSI) in Villigen, the international research group led by Michel Kenzelmann, a scientist at the Paul Scherrer Institute and professor at the Swiss Federal Institute of Technology Zurich, found a superconductor displaying two fascinating quantum properties. First, the material in the superconducting state shows magnetic order, which is a surprise given how superconductivity and magnetism cannot easily be accommodated in the same material.

Second, SINQ's experiments show that the electron pairs that form the superconducting state have a non-zero momentum, contrary to what is observed in all other known superconductors. Such a state has been theoretically predicted years ago, but it had never been microscopically detected.

Magnetism and Superconductivity

The transport of electric current in a conductor is associated with the displacement of electrons: Collisions between these electrons and the crystal ions cause resistance and release heat. In superconductors below the transition superconducting transition temperature, the electrons are form pairs, which allow them, thanks to quantum mechanics, to synchronize their motion with the ions, and all occupy the same quantum state. Electrons in their normal state can be seen as rush-hour pedestrians in a public plaza, yet electron pairs are like couples waltzing to the rhythm of the music without colliding.

The electron has a charge, but like a tiny magnet, it also has a magnetic moment called spin. In a singlet superconductor, the electron pairs are formed by electrons of opposite spin, which cancels the pair's magnetic moment. But when the material is placed in a strong magnetic field, the spins are forced to orient themselves along the field, as the field acts on each spin individually. Usually, this breaks the pairs and destroys superconductivity. The magnetic fields inside a magnetically ordered material tends to act in the same manner and thus that superconductivity and magnetism tend to avoid each other, although they are not always mutually exclusive.

According to Michel Kenzelmann, "Superconductivity and magnetism are like two groups of predators fighting over the same territory."

Superconductivity with magnetic consequences

In the experiment reported in Science, the scientists cooled a single crystal of CeCoIn5, a metal compound consisting of cerium, cobalt and indium, to a temperature of minus 273.1 degrees, close to absolute zero. To their great surprise, they discovered that magnetism and superconductivity coexist and disappear at the same time when they heat the sample or increase the magnetic field.

This discovery is extraordinary, since magnetic order exists exclusively when this sample is in the superconducting state. In this unique case, magnetism and superconductivity do not compete with each other. Instead, superconductivity generates magnetic order.

"Our results clearly indicate that superconductivity is a condition required to establish this magnetic order," says Kenzelmann. "Our work finally offers the possibility of understanding how superconducting pairs are formed in materials where this is caused by a magnetic interaction. We also hope that our results will allow the development of new technological applications in the near future."

New pairs

The research team also made a second discovery, which is detailed in the Science article – how electron pairs in the superconducting state in a strong magnetic field have a finite momentum. In all other known superconductors, the pairs form a state with zero momentum. Predicted by theorists a few decades ago, the observation of such a state in this experiment is the first experimental proof for such a new state of matter.

These two results allow for the first time to directly address questions about the relationship between magnetism and superconductivity. The answers that will be provided in the years ahead will allow a better understanding of this fascinating aspect of quantum mechanics and could even lead to the discovery of new technologically-important superconducting materials.

Andrea Bianchi | EurekAlert!
Further information:
http://www.umontreal.ca

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>