Single domain stripe order in a high-temperature superconductor

TL;DR

This study demonstrates that in a high-temperature superconductor, charge and spin density waves are directly coupled, emphasizing the importance of stripe fluctuations in understanding superconductivity.

Contribution

It introduces a novel neutron diffraction technique to directly observe the coupling of charge and spin density waves under uniaxial pressure in a cuprate superconductor.

Findings

Charge and spin density waves are immediately coupled.

Uniaxial pressure reveals the direct coupling between charge and spin orders.

Stripe fluctuations are crucial for models of high-temperature superconductivity.

Abstract

The coupling of spin, charge and lattice degrees of freedom results in the emergence of novel states of matter across many classes of strongly correlated electron materials. A model example is unconventional superconductivity, which is widely believed to arise from the coupling of electrons via spin excitations. In cuprate high-temperature superconductors, the interplay of charge and spin degrees of freedom is also reflected in a zoo of charge and spin-density wave orders that are intertwined with superconductivity. A key question is whether the different types of density waves merely coexist or are indeed directly coupled. Here we use a novel neutron diffraction technique with superior beam-focusing that allows us to probe the subtle spin-density wave order in the prototypical high-temperature superconductor La1.88Sr0.12CuO4 under applied uniaxial pressure to demonstrate that it is immediately coupled with charge-density wave order. Our result shows that suitable models for high-temperature superconductivity must equally account for charge and spin degrees of freedom via uniaxial charge-spin stripe fluctuations.