Metal Conductivity and Superconductivity
Metals conduct electricity well, but their conductivity changes with temperature.
At 20ºC, zinc's conductivity is 16.9 million siemens per meter.
When cooled to –272.3ºC, zinc becomes a superconductor with infinite conductivity.
This drastic change is due to electrons pairing up and behaving differently at very low temperatures.
Electron Behavior and Cooper Pairs
At room temperature, electrons in zinc move freely but are influenced by grid vibrations, impurities, and forces from protons in the nuclei.
Cooling the material weakens these forces, and below a critical temperature, the electrons form pairs known as Cooper pairs.
Cooper pairs behave differently than individual electrons, allowing the material to become superconductive, which means infinite conductivity.
Superconductors vs. Bose Metals
Superconductors like zinc have infinite conductivity below a critical temperature.
Some metals form Cooper pairs at low temperatures but don’t become superconductors; they remain better conductors.
These metals are called "Bose metals," an anomalous metallic state that doesn’t fully transition to superconductivity.
Bose metals are theorized to exist but have not yet been conclusively found.
Discovery of Bose Metal in NbSe2
Researchers found signs that niobium diselenide (NbSe2) could become a Bose metal.
NbSe2 behaves as a superconductor but allows magnetic fields to interact in small isolated pockets.
When NbSe2 is thinned and subjected to a magnetic field, it shows properties of a Bose metal.
The study’s findings suggest fluctuating Cooper pair behavior, which disrupts full superconductivity.
Implications for Physics and Future Research
Bose metals may not have current applications but offer valuable insights for understanding quantum behaviors in disordered materials.
Research on Bose metals challenges existing theories of metals at low temperatures and could inform future innovations.
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