#nickelates

Magnetic fields can 'revive' superconductivity in nickelates, research reveals

A research team led by Professor Denver Li Danfeng, Associate Dean (Research and Postgraduate Education) of the College of Science and Associate Professor in the Department of Physics at City University of Hong Kong (CityUHK), has achieved a significant advance in superconducting materials. Magnetic fields revive superconductivity The team has discovered a magnetic-field-induced "re-entrant superconductivity" phenomenon in infinite-layer nickelate superconductors, in which superconductivity—initially suppressed by a magnetic field—reappears at higher field strengths. This finding challenges the conventional understanding that magnetic fields suppress superconductivity and opens up new directions for exploring unconventional superconducting mechanisms and next-generation superconducting materials.

Nickelate superconductors share a common electronic fingerprint

Superconductors, materials that conduct electricity with zero electrical resistance at specific temperature ranges, have proved very promising for the development of quantum computers and other cutting-edge technologies. While most of these materials become superconducting at very low temperatures, others exhibit superconductivity at higher temperatures. Two types of materials that are known to be high-temperature semiconductors are cuprates (i.e., compounds containing negatively charged copper ions) and nickelates (i.e., compounds that contain negatively charged nickel-oxygen ions). While cuprates have been known to be superconductors for decades, nickelates were only recently found to exhibit superconductivity at unusually high temperatures.

Nickelate reveals nodeless gap, providing key clue to high-temperature superconductivity

The mechanism of high-temperature (TC) superconductivity is a key challenge in condensed matter physics. Recently, Chinese scientists made significant progress in the study of high-TC nickelate superconductors. Landmark observations in nickelate films For the first time, scientists observed a nodeless superconducting gap and discovered electron-boson coupling by measuring the electronic structures of Ruddlesden-Popper bilayer nickelate superconducting thin films. These results provide crucial evidence for two fundamental issues in the mechanism of high-TC nickelates: "superconducting gap symmetry" and "superconducting pairing mechanism."

'Superconducting dome' hints at high-temperature superconductivity in thin nickelate films

Superconductivity is a quantum state of matter characterized by an electrical resistance of zero and the expulsion of magnetic fields at low temperatures below a critical point. Superconductors, materials in which this state occurs, have proved to be highly advantageous for the development of various technologies, including medical imaging devices, particle accelerators and quantum computers. While superconductivity typically only occurs at extremely low temperatures, recent studies showed that in some materials it can arise at higher temperatures. These unconventional superconducting materials are referred to as high-temperature (high-Tc) superconductors.

Fragile no more, nickelates get an upgrade that changes how superconductivity endures

Discovered in 2019, the material known as nickelates has intrigued researchers for its potential to become a superconductor at elevated temperatures—a property that could significantly advance such fields as quantum science and energy transmission. However, it's a very unstable material and difficult to work with. But the lab of Professor Charles Ahn has developed a method that could enhance superconductivity in these materials. The results are published in Nature Communications. With their ability to conduct electricity with no resistance, superconductors are a key component to quantum computing, medical imaging, and a number of other fields. A group of copper-oxide compounds known as cuprates have long been central to the study of high-temperature superconductivity ("high temperature" is a relative term—they still need to be kept in very cold environments). Nickelates are especially exciting because they share some of cuprates' key electronic features while offering a new platform for materials design and tuning.

Research confirms Meissner effect in high-pressure nickelate superconductor

A research team led by Prof. Liu Xiaodi from the Hefei Institute of Physical Science of the Chinese Academy of Sciences, together with researchers from Jilin University and Sun Yat-sen University, has achieved simultaneous detection of zero electrical resistance and the Meissner effect in lanthanum nickelate (La3Ni2O7−δ) single crystals under high pressure. The researchers combined diamond nitrogen-vacancy (NV) center quantum sensing with electronic transport measurements to provide unambiguous evidence of high-temperature superconductivity in this nickelate system. The results are published in Physical Review Letters. Superconductivity in La3Ni2O7−δ was first reported in 2023 through transport measurements, which revealed zero resistance around 80 K. However, confirming superconductivity requires detecting diamagnetism, or the expulsion of magnetic fields—the Meissner effect—which had remained elusive due to technical challenges associated with high-pressure environments and small superconducting volume fractions.

Nickel superconductor works above -233°C threshold at normal pressure

A team of engineers and physicists at Southern University of Science and Technology, in China, has created a nickel-based material that behaves as a superconductor above the -233°C (40 K) threshold under ambient pressure. In their study published in Nature, the researchers synthesized thin films of bilayer nickelate (La₂.₈₅Pr₀.₁₅Ni₂O₇) and found one that behaved as a high-temperature superconductor. The -233°C threshold (40 K), often associated with the McMillan limit, marks a boundary beyond which conventional superconductivity theories become less predictive. Scientists have been searching for a room-temperature superconductor that could revolutionize a wide range of technologies. The ability to achieve superconductivity without the need for costly and complex cooling systems would significantly reduce energy loss due to heat conversion in electrical transmission, leading to dramatic improvements in efficiency and cost reduction. This breakthrough could lead to advancements in numerous fields, including maglev trains, fusion reactors and MRI machine components. This new effort by the team in China represents another step in reaching the ultimate goal.