High-energy magnetic excitations in underdoped La1.90Sr0.10CuO4

We measured the magnetic excitations in underdoped (UD) La1.90Sr0.10CuO4 by using inelastic neutron scattering over a wide energy range. We succeeded in observing the high-energy excitations up to ≃160 meV. Hour-glass-like magnetic excitation, which is commonly seen in the superconducting phase of cuprate oxides, was confirmed. The E cross (the energy where the dispersion is closest to the \(\left( {\tfrac{1} {2},\tfrac{1} {2}} \right)\) reciprocal position) of ∼40 meV follows a linear relation between E cross and the doped hole concentration in the UD region. From the dispersion of high-energy excitations above E cross, we successfully found an effective nearest neighbor interaction (J eff) of 102 ± 2 meV. This J eff is smaller than the nearest neighbor interaction J(=132 meV) in the parent compound La2CuO4, indicating a reduction of J eff by hole-doping.