Researchers have made progress towards a unified theory for high temperature superconductivity in copper-containing materials called cuprates. Superconductivity competes with magnetic spin and electric charge density wave (CDW) order in these materials.
In regular metals, electron spins cancel each other out and electrical charges are uniform. However, strong electron interactions in high-temperature superconductors give rise to other states. A new study published in Nature Communications has examined materials where strong magnetic interaction causes some electron spins to align along stripes.
This “stripe state” competes with the superconducting phase but researchers have found that short-range CDW can coexist and even enhance superconductivity, running counter to conventional wisdom.
The research also identified the possibility of using short-range charge order to stabilize superconductivity at higher temperatures and magnetic fields. The study provides important insight into developing a unified quantum description of superconductivity in cuprates.
The research used X-ray measurements on a previously uncharted high magnetic field regime of the cuprate La1.885Sr0.115CuO4. The results showed that the CDW order consists of two components with distinct dependencies on magnetic field and temperature.
The sample spontaneously segregated into superconducting and spin-charge stripe ordered regions, clarifying how long-range spin order and bulk superconductivity coexist. Surprisingly, a sudden enhancement to the CDW intensity was observed at high fields, commensurate with the vortex melting field.
This research supports the phase-disordering scenario for the superconducting transition, motivating a unified quantum description of density waves and superconductivity in cuprate superconductors.
[/INST]
Source: https://phys.org/news/2024-07-high-temperature-superconductivity-closer-theory.html