Global Sourcing Spotlight: 10 Rules of the Game
The Government Circuit: Support for Defense Spending Takes Top Priority
SMT Perspectives and Prospects: The AI Era, Part 3: LLMs, SLMs, and Foundation Models
Scientists Study the Insulator-Superconductor Transition of Copper-Oxide Compound in Fine Detail
April 11, 2016 | BNLEstimated reading time: 4 minutes
At a fixed low temperature, decreasing the doping level or increasing the applied magnetic field both suppressed superconductivity, allowing a competing state of electronic order to take over. Dramatic fluctuations appeared in the Hall resistance below a critical temperature, and these fluctuations increased in frequency and magnitude as all samples were further cooled toward absolute zero, indicating that they are of quantum origin.
"The behavior of these fluctuations is opposite to that seen in fluctuations driven by thermal energy, such as the vapor bubbles that appear when water is boiled," said Wu. "The bubbles fade away as the temperature is lowered."
The Hall resistivity measurements compared over the entire range of magnetic fields tested revealed that the samples have "memory" of their prior electronic states. After a magnetic field was applied, the value and sign of the Hall resistivity changed. When the magnetic field was removed, the samples stayed in the same electronic configuration until the field was reapplied—a very unusual property for conductors.
The scientists' data reveal that, at near-absolute-zero temperatures, the superconducting state competes with another state of electronic order characterized by the random distribution of many small charge "clusters," or localized groups of electrons. Unlike the free-flowing electrons in metals and superconductors, the electrons in these clusters are localized and pinned to particular atoms, rendering them immobile and unable to carry current when an electric field is applied. The clusters can hop around and trade places in the lattice as a result of quantum fluctuations.
"This picture explains the weak conductivity of this strange "insulating" state, revealing that the state originates from localization of charges," said Wu. "Our conclusion builds upon our understanding of the insulator-superconductor transition in an important class of high-temperature superconductors. We are one step closer toward our goal of predicting and designing new superconducting materials with superior properties for energy applications."
This research was funded by the Office of Science within the U.S. Department of Energy. Other authors include Anthony Bollinger of Brookhaven Lab and Yujie Sun of Brookhaven Lab and the Chinese Academy of Sciences.
Page 2 of 2Share on:
Suggested Items
Connect the Dots: Designing for Reality—Pattern Plating
10/16/2024 | Matt Stevenson -- Column: Connect the DotsIn the previous episode of I-Connect007’s On the Line with… podcast, we painted the picture of the outer layer imaging process. Now we are ready for pattern plating, where fabrication can get tricky. The board is now ready to receive the copper traces, pads, and other elements specified in the original CAD design. This article will lay out the pattern plating process and discuss constraints in the chemistries that must be properly managed to meet the customer's exacting manufacturing tolerances.
PCB007 Magazine October 2024: Alternate Metallization Processes
10/16/2024 | I-Connect007 Editorial TeamTraditional electroless copper and electroless copper immersion gold have been primary PCB plating methods for decades. But alternative plating metals and processes have been introduced over the past few years as miniaturization and advanced packaging continue to develop taking us into new directions. In this issue of PCB007 Magazine, we examine the impact of alternate metallization methods giving a glimpse into how and when we will arrive at 'destination metallization'.
Partial HDI: A Complete Solution
10/10/2024 | I-Connect007 Editorial TeamWe recently spoke with IPC instructor Kris Moyer about partial HDI, a process that’s recently been growing in popularity. Partial HDI allows designers to escape route out from tight-pitch BGAs on one layer, where a mechanically drilled plated through-hole is not an option, while avoiding the complexity and expense of sequential lamination cycles. As Kris explains, this process doesn’t add much to the cost, and it’s fairly straightforward. But there are some competing signal integrity and fabrication requirements to contend with. We asked Kris to walk us through this process.
Trouble in Your Tank: Interconnect Defect—The Three Degrees of Separation
10/01/2024 | Michael Carano -- Column: Trouble in Your TankIt has been well documented that, with a very expensive and complex printed circuit board, thermal and mechanical excursions often find weaknesses. A lack of robustness and poor process control often leads to the exploitation of those weaknesses. An interconnect defect (ICD) often goes undetected until the printed circuit board reaches the final assembly stage or undergoes multiple thermal cycles, including interconnect stress tests or thermal shock. It is impossible to rework the ICD defect. But unlike voids, if detected in time, the panels can be reprocessed.
Connect the Dots: Designing for Reality—Outer Layer Imaging
09/26/2024 | Matt Stevenson -- Column: Connect the DotsWelcome to the next step in the manufacturing process—the one that gets the chemical engineer in all of us excited. I am referring to outer layer imaging, or how we convert digital designs to physical products. On a recent episode of I-Connect007’s On the Line with… podcast, we explained how the outer layer imaging process maps the design’s unique features onto the board.