Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists shine new light on the “other high temperature superconductor”

09.08.2017

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus 273 degrees Celsius). Only in the 1980s, physicists managed to synthetize new classes of compounds, based on ceramic materials, which were able to conduct electricity without any losses at temperatures as high as 138 K (minus 135 degrees Celsius). These were named “high temperature superconductors”.


Intense laser pulses were used to photo-excite bismuthate compounds, in which “charge-density-waves” (left side) coexist with superconductivity (right side).

Image: Joerg M. Harms, MPSD

The best known and heavily studied family of high temperature superconductor is that of cuprates, which display by far the highest critical temperatures (i.e. the temperature below which superconductivity occurs), and are therefore the most promising for applications. However, a wide variety of other compounds exists, which also manifest superconductivity at fairly high temperatures, among them the recently discovered iron pnictides.

A universal picture able to describe the physics behind the phenomenon of high temperature superconductivity is still missing. However, an important commonality between almost all high temperature superconductors is the emergence of superconductivity in proximity of other exotic phases of matter, such as the “charge-density-waves”.

All these materials can be typically tuned from one phase to another, possibly achieving superconductivity, by chemical doping, external pressure, or magnetic fields. However, the subtle inter-relation of these phases remains poorly understood, and in some case, there are evidences that charge-density-waves and superconductivity can even coexist microscopically in the very same compound.

In such circumstances, experiments performed by stimulating materials with ultrashort, intense laser pulses (as short as few hundreds of femtoseconds) have been shown in the past to provide new insights in the physics of these systems. For example, the group of Andrea Cavalleri at the MPSD in Hamburg has already successfully demonstrated that, in some cuprates compounds, such pulses can be used to remove charge-density-waves and promote superconductivity at higher temperatures, possibly even up to room temperature (see links below: W. Hu, Nature Materials, 13, 705–711 and R. Mankowsky, Nature 516 , 71–73).

In the present work, Nicoletti, Cavalleri and coworkers focused on different compounds, belonging to the poorly studied family of bismuthates. These superconductors were discovered in the 1970s, even before the cuprates, but they attracted less attention due to their far lower critical temperatures (about 30 K). They share many commonalities, but also some differences with their better-known relatives. In particular, the so-called “parent compound”, BaBiO(3), has a robust charge-density-wave phase, from which superconductivity emerges by chemical substitution.

High quality crystals of BaPb(1-x)BixO(3), with different Pb concentrations “x”, were synthetized and characterized by Ian R. Fisher and P. Giraldo-Gallo at Stanford University, California. The Hamburg team performed a series of experiments on these crystals, in which they photo-excited the materials with very short and intense laser pulses and measured how their conductivity was transiently modified and relaxed back to the initial value within few picoseconds.

By analysing the dependence of such signal on frequency, temperature, and Pb concentration, they could uniquely assign it to a modification of the charge-density-wave phase induced by the laser field.

“Strikingly”, says Nicoletti, “we were able to measure this response not only in the parent compound BaBiO(3), for which a charge-density-wave is well known to exist, but also in a Pb-doped superconducting compound. This observation is an indirect demonstration of the coexistence of charge-density-waves and superconductivity in the very same material, something that has been discussed previously, but never definitely established in this class of materials”.

The scientists were also able to exactly determine the energy scales associated with the modification of the charge-density-waves, thus providing new information on their dynamical interplay with superconductivity in bismuthates.

These results are especially timely given that charge-density-waves have recently been found in several cuprate superconductors, pointing towards a surprising commonality between some aspects of these materials. The present experiment is an additional example of how light can be employed to investigate, control, and manipulate complex materials. One of the ultimate goals of this line of research is to provide guidance for material engineering to develop new functionalities at increasingly higher temperatures.

This work was supported by the ERC Synergy Grant “Frontiers in Quantum Materials’ Control” (Q-MAC), the Hamburg Centre for Ultrafast Imaging (CUI), and the priority program SFB925 of the Deutsche Forschungsgemeinschaft. The experiments were performed in the laboratories of the Center for Free-Electron Laser Science (CFEL), a joint enterprise of DESY, the Max Planck Society, and the University of Hamburg. The research was carried out in close collaboration with scientists of Stanford University, California, USA.

Contact: Dr. Daniele Nicoletti, corresponding author, +49 (0)40 8998-6208, daniele.nicoletti@mpsd.mpg.de

Weitere Informationen:

https://dx.doi.org/10.1073/pnas.1707079114 - Original publication
http://www.mpsd.mpg.de/116013/1412-vibes-for-superc-cavalleri - Superconductivity without cooling (2014)
http://www.mpsd.mpg.de/84292/2014-05-hint-for-sc-at-room-temperature - A first hint for superconductivity at room temperature (2014)

Dr. Joerg Harms | Max-Planck-Institut für Struktur und Dynamik der Materie

More articles from Materials Sciences:

nachricht Transporting spin: A graphene and boron nitride heterostructure creates large spin signals
16.08.2017 | Graphene Flagship

nachricht From hot to cold: How to move objects at the nanoscale
10.08.2017 | Scuola Internazionale Superiore di Studi Avanzati

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>