A new strategy to fabricate and manipulate higher temperature superconductors

Graphical representation of a stacked, twisted cuprate superconductor, with associated background data. Credit: Lucy Yip, Yoshi Saito, Alex Cui, Frank Zhao

Superconductors have intrigued physicists for decades. But these materials, which allow the perfect, lossless flow of electrons, usually only exhibit this quantum-mechanical peculiarity at temperatures so low as a few degrees above absolute zeroas to make them impractical. .

A research group led by Harvard Professor of Physics and Applied Physics Philip Kim has demonstrated a new strategy for creating and manipulating a widely studied class of higher-temperature superconductors. called cuprates, clearing a path to engineering new, unusual forms of superconductivity in previously unattainable materials. .

Using a unique method to create the low-temperature device, Kim and his team reported in the journal Science a promising candidate for the world’s first high-temperature, superconducting diodeessentially, a switch that conducts current in one direction made of thin cuprate crystals.

Such a device could fuel new industries such as quantum computing, which rely on transient mechanical phenomena that are difficult to maintain.

“High temperature superconducting diodes are, in fact, possible, without the use of a magnetic field, and open new doors of inquiry into exotic materials study,” said Kim.

Cuprates are copper oxides that, decades ago, rocked the world of physics by showing that they became superconducting at higher temperatures than theorists thought possible, “higher” being a relative term. (the current record for a cuprate superconductor is -225 Fahrenheit). However, handling these materials without destroying their superconducting phases is extremely complex due to their intricate electronic and structural features.

The team’s experiments were led by SY Frank Zhao, a former student at the Griffin Graduate School of Arts and Sciences and now a postdoctoral researcher at MIT. Using an airless, cryogenic method of manipulating the crystal in ultrapure argon, Zhao engineered a clean interface between two very thin layers of cuprate bismuth strontium calcium copper oxide, nicknamed BSCCO (“bisco”).

BSCCO is considered a “high temperature” superconductor because it starts superconducting at about -288 Fahrenheit (-177 C) very cold by practical standards but surprisingly high for superconductors, which usually have to be cool to about -400 Fahrenheit (-240 C) .

Zhao first split the BSCCO into two layers, each one a thousandth of the width of a human hair. Then, at -130 F (- 90 C), he stacked the two layers in a 45-degree twist, like an ice cream sandwich with wafers askew, retaining the superconductivity of the weak interface.

The team discovered that the maximum supercurrent that can pass without resistance at the interface differs depending on the direction of the current. In fact, the team also demonstrated electronic control of the interfacial quantum state by changing its polarity.

This control is what effectively allowed them to create a switchable, high-temperature superconducting diodea demonstration of foundational physics that could one day be incorporated into a piece of computer technology, such as a quantum bit.

“This is a starting point for investigating topological phases, with quantum states protected from imperfections,” Zhao said.

The Harvard team worked with colleagues Marcel Franz of the University of British Columbia and Jed Pixley of Rutgers University, whose teams had previously performed theoretical calculations that accurately predicted the behavior of cuprate superconductors over a wide range of angles. in a twist. Reconciliation of experimental observations also required new developments in theory made by the University of Connecticut’s Pavel A. Volkov.

Correction Note (12/182023): Celsius degrees were added to the article to complement the Fahrenheit measurements.

More information:
SY Frank Zhao et al, Time-reversal symmetry breaking superconductivity between twisted cuprate superconductors, Science (2023). DOI: 10.1126/science.abl8371

Given by Harvard University

Citation: A new strategy to create and manipulate higher temperature superconductors (2023, December 18) retrieved on December 24, 2023 from https://phys.org/news/2023-12-strategy-higher -temperature-superconductors.html

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