#superconductors

For more than 30 years, a record in science held firm: minus 220 degrees Fahrenheit. It defined the highest achieved temperature for any material to become superconducting - able to carry electricity with no resistance - without the need for crushing pressures. In a field known for slow, steady progress, the record had come to seem almost immovable. That limit has always been daunting because most known superconductors work only at temperatures close to absolute zero - hundreds of degrees below zero Fahrenheit. Keeping materials so ultracold requires complex and costly cooling systems. This limits where and how these materials can be applied to niche technologies, like MRI scanners and particle accelerators.

New superconducting X-ray detector is up to 1,000 times more sensitive

A major new tool for X-ray research has entered service at BESSY II. Developed through a collaboration between HZB, MPI-CEC (Mühlheim-an-der-Ruhr, Germany), and NIST (Boulder CO, USA), the instrument is the first and only TES spectrometer operating at a synchrotron facility in Europe. The new system delivers a dramatic improvement in photon detection efficiency, outperforming conventional wavelength-dispersive X-ray emission spectrometers by a factor of 100 to 1000. Researchers plan to use it to study the electronic properties of atomically thin materials, nanostructures, and highly diluted atomic and molecular samples. The team is now inviting research proposals from the scientific community.

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."

Observing exotic quasiparticle states in kagome superconductor CsV₃Sb₅

A research team led by Prof. Hao Ning of the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, in collaboration with Anhui University and the University of Science and Technology of China, has identified two distinct types of unusual low-energy quasiparticle states in the kagome superconductor CsV3Sb5 using single-atom impurities as local "quantum probes" combined with scanning tunneling spectroscopy. The study was recently published in Nature Physics. CsV3Sb5 has attracted growing interest for its unusual crystal structure and complex quantum phenomena. Evidence for time-reversal symmetry breaking remains under debate, and the mechanism of its superconductivity is still not fully understood. Studying its response to single-atom impurities provides a promising way to address these questions.

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.

Surprising link between metallicity and superconductivity uncovered in twisted trilayer graphene

Superconductivity is a state of matter characterized by an electrical resistance of zero, typically at very low temperatures. Past studies have found that in various materials, this unique state is accompanied by unusual electron arrangements. In some superconductors, for instance, electrons spontaneously align in a preferred direction, breaking a property known as rotational symmetry. This directional arrangement of electrons is also known as electronic nematicity. Moreover, some superconductors also exhibit a strange metallicity. This is a phase characterized by unusual changes in a material's electrical resistance, which cannot be explained by standard physical theories.

Unlocking unusual superconductivity in a lightweight element

Superconductors—materials that can conduct electricity without energy loss—are crucial for next-generation high-efficiency, ultrafast electronics. However, most superconductors share a critical limitation: they lose their superconducting properties in strong magnetic fields. In contrast, a class of superconductors containing heavy elements can sustain an unusual type of superconductivity in magnetic fields beyond the conventional limit. Now, new research has demonstrated that this limitation can be overcome by sandwiching atomically thin films of a lightweight element called gallium between two other materials to engineer quantum interactions at the interfaces between the layers.