High-pressure studies of Charge-Density-Wave Superconductors

Lead Research Organisation: University of Bristol
Department Name: Physics


Superconductivity and Charge-Density-Wave order are intriguing states of matter. In particular superconductivity has an enormous technological potential. The lossless transmission of electrical power in superconductors can be used to make huge energy savings. Indeed, first prototypes of superconducting power lines are being established in the USA and Korea. Superconductors also facilitate high stable magnetic fields used for magnetic resonance scanning in healthcare and are one of the most promising routes towards quantum computing.

Currently the potential of superconductivity for applications is held back by limitations to the understanding of the microscopic origin. Further understanding of superconductivity and related phenomena is likely to allow much wider applications. This grant will study the interplay of Superconductivity and charge-density-wave order.

Traditionally, the superconductivity and charge-density-wave order are thought to be in competition with superconductivity often weakened by the presence of charge-density-wave order. Yet, the recent discovery of charge-density-wave order in high-temperature copper-oxide superconductors raises the possibility of superconductivity being driven by charge-density-wave order. Unfortunately, copper-oxide superconductors are very complex materials where it is difficult to disentangle the effects of the charge-density-wave order from other phenomena. This is why we will study less complicated model systems.

We explore the limits of various theoretical scenarios in selected model materials and relate those results to the high-temperature copper-oxide superconductors. We study materials that show a promotion of superconductivity, as well as coexisting and competing superconductivity. We measure the key determinants for the superconductivity and the charge-density-wave order. For the first time we will measure the evolution of the Fermi surface and electron-phonon coupling using high-pressure quantum oscillation studies. Our novel approach will shed light on the mechanism of both the charge-density-wave order and superconductivity in these materials and will guide theory on both superconductivity and charge-density-wave order and intriguing material properties caused by these.

Planned Impact

The project will investigate charge-density-wave superconductors. This research will be of relevance to both the understanding and future application of superconductors and electronic materials.

Superconductors are used in wide-ranging applications. Most importantly for magnetic resonance imaging in health care and increasingly in power transmission. Improving the properties of superconductors can lead to much wider applications. Global research aims to improve the two key parameters, the transition temperature and the amount of current superconductors can carry. If these efforts are successful and can be combined with favourable mechanical properties of superconducting materials further applications and new devices will result. This could for instance be a grid of superconductors for lossless power distribution, levitating trains for energy efficient transport like the Shanghai Maglev Train in China.

Our research will contribute to the crucial step of understanding the fundamental mechanisms of superconductivity in high-temperature superconductors. It will contribute to clarifying the interplay of charge-density-wave order and superconductivity and contribute to identifying to what extend these two phenomena are antagonistic or supportive. We will use electronic structure measurements to reveal the interplay of superconductivity and charge-density-wave order in model materials with less complexity then cuprate high-temperature superconductivity. These results will guide researchers in identifying the nature of this interplay in cuprate superconductors. This will contribute towards enhancing the transition temperature and boost the potential for applications.
Description This research project studies the interaction of superconductivity and charge-density wave order. Whilst these two phenomena are generally expected to be in competition with each other, we found evidence that they are independent of each other in cuprate high-temperature superconductors. We used high-pressure to show that the enhancement of the superconductivity is accompanied only by a very weak suppression of the charge-density wave order. Thus, our results will help to understand the physics of cuprate high-temperature superconductors.
Exploitation Route High-temperature superconductors have a huge potential for applications. At the moment they are used in power transmission, and tested for magnetic imaging in medicine. Further applications are hindered by the need to cool and difficult mechanical materials properties. This research is contributing to the understanding of superconductivity and thus expected to help find new superconductors with improved characteristics. This impact is mainly achieved through publications in scientific journals and presentations at conferences which are received well in the academic community.
Sectors Electronics,Energy,Healthcare,Manufacturing, including Industrial Biotechology,Other

Title Pressure Cell for Measurements at High-Magnetic-Field Facilities 
Description Both Pressure and high magnetic fields are important probes for research in solid state physics. High Magnetic fields can be used to study the characteristics of superconductors and the electronic structure of metals. High pressures allow to tune materials properties without introducing disorder or symmetry breaking. Combining the two opens new avenues to address immanent questions on superconductivity, correlated metals, topological materials, and many more. As part of this research programme, we have developed and successfully used anvil type high-pressure cells that fit into the small samples space for low-temperature measurements in the magnets at the High Field Magnet Laboratory in Nijmegen, Netherlands. 
Type Of Material Improvements to research infrastructure 
Year Produced 2017 
Provided To Others? No  
Impact Publications as listed for this grant. Further publications will follow soon.