Identification of intrinsic gapped behavior in spin-1/2 ladder with staggered dimerization

► The ground state phase diagram of the spin-1/2 two-leg ladder with staggered dimerization. ► The thermodynamic properties of the spin-1/2 two-leg ladder with staggered dimerization. ► The intrinsic gapped low-lying excitations are responsible for the thermodynamic behaviors.