Odd and even magnetic resonant modes in highly overdoped Bi_2 Sr_2 Ca Cu_2 O_{8+delta}

TL;DR

This study reports inelastic neutron scattering measurements revealing odd and even magnetic resonant modes in highly overdoped Bi-2212, confirming their universality across doping levels and providing insights into the magnetic excitations in cuprate superconductors.

Contribution

It provides the first detailed observation of both odd and even magnetic resonant modes in highly overdoped Bi-2212, extending the understanding of magnetic excitations in cuprates.

Findings

Both odd and even resonant modes are observed in overdoped Bi-2212.

The linewidth of the odd mode is reduced in the overdoped sample.

Results are consistent with trends seen in other cuprates, confirming universality.

Abstract

We present inelastic neutron scattering data on highly overdoped Bi_2 Sr_2 Ca Cu_2 O_{8+\delta} single crystals with superconducting transition temperature T_C=70 K and, for comparison, a nearly optimally doped crystal with T_C=87 K. In both samples, magnetic resonant modes with odd and even symmetry under exchange of the two CuO_2 layers in the unit cell are observed. In the overdoped sample, the linewidth of the odd mode is reduced compared with the optimally doped sample. This finding is discussed in conjunction with recent evidence for intrinsic inhomogeneities in this compound. The data on odd and even resonant excitations are otherwise fully consistent with trends established on the basis of data on YBa_2Cu_3O_{6+x}. This confirms the universality of these findings and extends them into the highly overdoped regime of the phase diagram.