Hydrogen blamed for interfering with nickelate superconductors synthesis

May 08, 2020

Prof. ZHONG Zhicheng's team at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences has investigated the electronic structure of the recently discovered nickelate superconductors NdNiO2.

They successfully explained the experimental difficulties in synthesizing superconducting nickelates, in cooperation with Prof. Karsten Held at Vienna University of Technology (TU Wien) in Austria. The findings were published in Physical Review Letters (Phys. Rev. Lett.).

In August of 2019, high-temperature superconductivity was demonstrated in nickelates (i.e., Sr-doped NdNiO2), which are able to conduct electric current even at high temperatures. This seminal work heralded the nickel age of superconductivity.

However, reproducing these outstanding results appeared to be quite challenging. Other researchers even reported that their nickelates did not have superconducting properties.

To clarify this divergence, the researchers at NIMTE performed calculations based on density functional theory (DFT) and dynamical mean field theory with the help of supercomputers.

The chemical reduction of ABO3 (A: rare earth; B: transition metal) with CaH2 may result in both ABO2 and ABO2H. The topotactic hydrogen (H) in nickelates was found to be energetically favorable for LaNiO2 but not for Sr-doped NdNiO2, leading to dramatic consequences for the electronic structure: That of 3d9 LaNiO2 is similar to (doped) cuprates, while 3d8 LaNiO2H is a two-orbital Mott insulator.

Therefore, H can be incorporated into the material structure of some nickelates and thus completely changes the electronic properties of the material.

Recently, this proposal was verified by researchers from the National University of Singapore (NUS). They dispersed the H that was released in the production process and succeeded in synthesizing superconducting nickelates.

The current study might account for the difficulties in synthesizing nickelate superconductors and explain why some nickelates are superconducting and others are not. In addition, the study offers suggestions for producing nickelate superconductors: with compressive strain and Sr doping, long reaction times to reduce H2 pressure, and low temperatures.
-end-


Chinese Academy of Sciences Headquarters

Related Superconducting Articles from Brightsurf:

Rochester researchers synthesize room temperature superconducting material
Compressing simple molecular solids with hydrogen at extremely high pressures, University of Rochester scientists have, for the first time, created material that is superconducting at room temperature.

Topological superconducting phase protected by 1D local magnetic symmetries
Scientists from China and USA classified 1D gapped topological superconducting quantum wires with local magnetic symmetries (LMSs), in which the time-reversal symmetry is broken but its combinations with certain crystalline symmetries, such as MxT, C2zT, C4zT, and C6zT, are preserved.

Skoltech and MIPT scientists find a rule to predict new superconducting metal hydrides
The search for coveted high-temperature superconductors is going to get easier with a new 'law within a law' discovered by Skoltech and MIPT researchers and their colleagues, who figured out a link between an element's position in the Periodic Table and its potential to form a high-temperature superconducting hydride.

Scientists created an 'impossible' superconducting compound
Scientists have created new superconducting compounds of hydrogen and praseodymium, a rare-earth metal, one substance being quite a surprise from the perspective of classical chemistry.

Quantum technologies: New insights into superconducting processes
Superconductors are regarded as promising components for quantum computers, but so far they only function at very low temperatures.

Superconducting wind turbine chalks up first test success
A superconducting rotor has been successfully tested on an active wind turbine for the first time.

New design strategy can help improve layered superconducting materials
Tokyo, Japan - Scientists from Tokyo Metropolitan University have created a new layered superconducting material with a conducting layer made of bismuth, silver, tin, sulfur and selenium.

Controlling superconducting regions within an exotic metal
Researchers at EPFL have created a metallic microdevice in which they can define and tune patterns of superconductivity.

Evidence of anomalously large superconducting gap on topological surface state of β-Bi2Pd film
Hong Ding's group from the Institute of Physics, Chinese Academy of Science reported the superconducting gap of topological surface state is larger than that of bulk states in β-Bi2Pd thin films using in-situ angle-resolved photoemission spectroscopy and molecular beam epitaxy.

Two advances in understanding the role of 'charge stripes' in superconducting mate
In independent studies, two research teams report important advances in understanding how charge stripes might interact with superconductivity.

Read More: Superconducting News and Superconducting Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.