Scanning tunneling spectroscopic evidence for magnetic field-induced microscopic orders in the high-$T_c$ superconductor YBa$_2$Cu$_3$O$_{7-\delta}$

TL;DR

This study provides spectroscopic evidence that magnetic fields induce microscopic orders such as charge, spin, and pair-density waves in the high-$T_c$ superconductor YBa$_2$Cu$_3$O$_{7-\delta}$, revealing complex vortex-state phenomena.

Contribution

It presents direct spectroscopic evidence of field-induced microscopic orders in a high-$T_c$ superconductor, highlighting new wave-vectors associated with these orders distinct from quasiparticle interference.

Findings

Spectral weight shifts from superconducting gap to pseudogap with increasing magnetic field.

Energy-independent conductance modulations at specific lattice constants in the vortex state.

Identification of wave-vectors potentially linked to microscopic orders such as charge and spin density waves.

Abstract

We report spatially resolved tunneling spectroscopic evidence for field-induced microscopic orders in a high-$T_c$ superconductor $\rm YBa_2Cu_3O_{7-\delta}$. The spectral characteristics inside vortices reveal a pseudogap ($V_{\rm CO}$) larger than the superconducting gap ($\Delta\_{\rm SC}$) as well as a subgap ($\Delta\^{\prime}$) smaller than $\Delta\_{\rm SC}$, and the spectral weight shifts steadily from $\Delta_{\rm SC}$ to $V_{\rm CO}$ and $\Delta\^{\prime}$ upon increasing magnetic field. Additionally, energy-independent conductance modulations at 3.6 and 7.1 lattice constants along the Cu-O bonding directions and at 9.5 lattice constants along the nodal directions are manifested in the vortex state. These wave-vectors differ fundamentally from the strongly dispersive modes due to Bogoliubov quasiparticle scattering interferences and may be associated with field-induced microscopic orders of pair-, charge- and spin-density waves.