Coexistence of the spin liquid state and the magnetic ordering in the spin ladder compound; Sr 14− xCa xCu 24O 41

Abstract

The magnetic ground state in the hole-doped two-leg ladder system Sr 2.5Ca 11.5Cu 24O 41 both at ambient pressure and under high pressure up to 3 GPa was investigated by a neutron scattering experiment. The spin gap value for this system at ambient pressure is found to be 32.1±0.3 meV, being almost the same as that of the parent material Sr 14Cu 24O 41. With increasing pressure, the spin gap energy is almost unchanged, however, the inelastic neutron scattering intensity at the zone center of the ladder is decreased progressively. We also observed antiferromagnetic long range ordering below T N(∼2.1 K), which was increased with increasing pressure. A possible magnetic structure of this system is also discussed. These results show the coexistence of the spin liquid state and antiferromagnetic ordering in the hole-doped two-leg ladder system.