Odd-parity spin-loop-current order mediated by transverse spin fluctuations in cuprates and related electron systems

Unconventional symmetry-breaking phenomena due to nontrivial order parameters attract increasing attention in strongly correlated electron systems. Here, we predict theoretically the occurrence of nanoscale spontaneous spin current, called the spin-loop-current (sLC) order, as a promising origin of the pseudogap and electronic nematicity in cuprates. We reveal that the sLC is driven by the odd-parity electron-hole condensations that are mediated by transverse spin fluctuations around the pseudogap temperature T*. At the same temperature, odd-parity magnon pair condensation occurs. The sLC order is hidden in that neither internal magnetic field nor charge-density modulation is induced, whereas the predicted sLC with finite wave-number naturally gives the Fermi arc structure. In addition, the fluctuations of sLC order work as attractive pairing interaction between adjacent hot spots, which enlarges the d-wave superconducting transition temperature T-c. The sLC state will be a key ingredient in understanding the pseudogap, electronic nematicity, as well as superconductivity in cuprates and other strongly correlated metals.

Automated summary

Theoretical prediction of nanoscale spontaneous spin current order in cuprates, driven by odd-parity electron-hole condensations and mediated by transverse spin fluctuations. The fluctuations of sLC order work as attractive pairing interaction between adjacent hot spots, increasing the d-wave superconducting transition temperature T-c. The sLC state serves as a key ingredient in understanding the pseudogap, electronic nematicity, and superconductivity in cuprates.