Evidence for an incommensurate magnetic resonance inLa2−xSrxCuO

Abstract

We study the effect of a magnetic field (applied along the c-axis) on the low-energy, incommensurate magnetic fluctuations in superconducting La1.82Sr0.18CuO4. The incommensurate peaks at 9 meV, which in zero-field were previously shown to sharpen in q on cooling below Tc [T. E. Mason et al., Phys. Rev. Lett. 77, 1604], are found to broaden in q when a field of 10 T is applied. The applied field also causes scattered intensity to shift into the spin gap. We point out that the response at 9 meV, though occurring at incommensurate wave vectors, is comparable to the commensurate magnetic resonance observed at higher energies in other cuprate superconductors.

Neutron Scattering Studies of Antiferromagnetic Correlations in Cuprates

“…Instead, the field moves spectral weight into the spin gap. The study on x = 0.18 indicated that the increase in weight in the gap is accompanied by a decrease in the intensity peak above the gap [51], the latter result being comparable to the effect seen in YBa 2 Cu 3 O 6.6 [50]. For x = 0.163, an enhancement of the incommensurate scattering was observed below 10 K forhω = 2.5 meV.…”

“…For an intermediate doping concentration of x = 0.144, Khaykovich et al [230] have recently shown that, although no elastic magnetic peaks are seen at zero field, a static SDW does appear for H > H c ∼ 3 T. Such behavior [224], [223], [230], [52], and [51]. The solid curve suggests the shape of a boundary between a state with spin-density-wave order and superconductivity on the left and superconductivity alone on the right, as first proposed by Demler et al [225].…”

A Unified Theory for the Cuprates, Iron-Based and Similar Superconducting Systems: Application for Spin and Charge Excitations in the Hole-Doped Cuprates

“…2; the small-and large-spin-gap results demonstrate, respectively, the existence of an incommensurate [34] or a commensurate [33] resonance mode.…”

“…Also, in both systems the suppression of SC by a high magnetic field results in a zero-temperature insulator-to-metal transition upon doping [24,25]. Even though the pairing symmetry is different in the cuprates [26][27][28] and the FeSCs [29-32], a resonant spin excitation, characterized by wave vectors around those of the magnetic order in the parent compound, exists in the SC state of both systems [33][34][35].…”

“…Also, in both systems the suppression of SC by a high magnetic field results in a zero-temperature insulator-to-metal transition upon doping [24,25]. Even though the pairing symmetry is different in the cuprates [26][27][28] and the FeSCs [29-32], a resonant spin excitation, characterized by wave vectors around those of the magnetic order in the parent compound, exists in the SC state of both systems [33][34][35].The approximate tetrahedral arrangement of the pnictogen/chalcogen atoms around the iron atoms in the FeSCs is typical of covalent bonding, and thus considerable hybridization is expected between orbitals corresponding to the two atoms. This is confirmed in electronic-structure calculations [10][11][12][13][14][15][16]; however, such hybridization is found in antibonding and bonding states which lie at least ∼ 1 eV away from the Fermi level (E F ), while the states at the close vicinity of E F are non- * Electronic address: jashkenazi@miami.edu bonding and of almost a pure Fe(3d) nature [12][13][14][15][16].…”