Correlation between scale-invariant normal-state resistivity and superconductivity in an electron-doped cuprate.
basic_science · Level V
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- Record sourced from PubMed, PMID 31114800.
- Also identified by DOI 10.1126/sciadv.aav6753 and PMC identifier 6524976.
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Abstract
An understanding of the normal state in the high-temperature superconducting cuprates is crucial to the ultimate understanding of the long-standing problem of the origin of the superconductivity itself. This so-called "strange metal" state is thought to be associated with a quantum critical point (QCP) hidden beneath the superconductivity. In electron-doped cuprates-in contrast to hole-doped cuprates-it is possible to access the normal state at very low temperatures and low magnetic fields to study this putative QCP and to probe the <i>T</i> ➔ 0 K state of these materials. We report measurements of the low-temperature normal-state magnetoresistance (MR) of the n-type cuprate system La<sub>2-<i>x</i></sub> Ce <i><sub>x</sub></i> CuO<sub>4</sub> and find that it is characterized by a linear-in-field behavior, which follows a scaling relation with applied field and temperature, for doping (<i>x</i>) above the putative QCP (<i>x</i> = 0.14). The magnitude of the unconventional linear MR decreases as <i>T</i> <sub>c</sub> decreases and goes to zero at the end of the superconducting dome (<i>x</i> ~ 0.175) above which a conventional quadratic MR is found. These results show that there is a strong correlation between the quantum critical excitations of the strange metal state and the high-<i>T</i> <sub>c</sub> superconductivity.