Clues About Unconventional Superconductivity From High-Field Hall Data

Published December 13, 2021

A quantum phase transition detected using pulsed fields. On one side of the transition (purple curve) the Hall resistivity grows steeply with field, once the linear regime has been accessed in high magnetic fields; on the other side (red curve), the increase is slower. Inset: the quantum phase transition is evidenced by the steep jump with increasing electron concentration in data from a dozen samples.

In everyday life, phase transitions - like when water boils and turns into steam or freezes and becomes ice - are caused by changes in temperature. Here, very high magnetic fields are used to reveal a quantum phase transition not caused by temperature, but instead driven by quantum mechanics upon changing the concentration of electrons, work that could hold critical clues that explain high-temperature superconductivity.

Why is this important?

Electrical current can run through a superconductor without dissipating energy, making them invaluable in energy-efficient devices. However, traditional superconductors, typically based upon niobium compounds, work only at temperatures close to absolute zero, restricting their usefulness. By contrast, superconductivity in the cuprate superconductors persists to temperatures of ~100 Kelvin. However, the mechanism behind this behavior remains a mystery.

These new measurements on CeCoIn5, a close relative of the cuprates, show that the quantum phase transition is linked to their superconductivity, likely a vital clue towards the understanding high temperature superconductivity as resulting from proximity to a quantum phase transition.

Who did the research?

N. Maksimovic^1,2 D. Eilbot,^1,2 T. Cookmeyer,^1,2 F. Wan,^1,2 J. Rusz,³ V. Nagarajan,^1,2 S. Haley,^1,2 E. Maniv,^1,2 A. Gong,^1,2 S. Faubel,^1,2 I. Hayes,^1,2 A. Bangura,⁴ J. Singleton,⁵ J. Palmstrom,⁵ L. Winter,⁵ R. McDonald,⁵S. Jang,^1,2, P. Ai,² Y. Lin,² S. Ciocys,^1,2 J. Gobbo,^1,2 Y. Werman,^1,2 P. Oppeneer,³ E. Altman,^1,2 A. Lanzara,^1,2, J. G. Analytis^1,2

¹Physics, UC Berkeley, USA; ²Materials Sciences Division, Lawrence Berkeley National Laboratory, USA ³Physics and Astronomy, Uppsala University, Sweden; ⁴National MagLab Tallahassee, USA; ⁵National MagLab Los Alamos, USA.

Why did they need the MagLab?

Intense magnetic fields drive the samples through phase transitions until the Hall resistance varies linearly with field. Once this straight-line behavior is observed over as wide a magnetic field range as possible, a determination of a sudden change in slope with electron concentation indicates the quantum phase transition.

Details for scientists

View or download the expert-level Science Highlight, Clues about unconventional superconductivity from high-field Hall data
Read the full-length publication Evidence for a delocalization quantum phase transition without symmetry breaking in CeCoIn₅, in Science

Funding

This research was funded by the following grants: J.G. Analytis (NSF DGE-1752814; Gordon and Betty Moore Foundation GBMF9067), G.S Boebinger (NSF DMR-1644779); P. Oppeneer (Swedish Research Council; K. and A. Wallenberg Foundation Award 2015.006).

For more information, contact John Singleton.