Random Antiferromagnetic SU(N) Spin Chains

Abstract

We analyze random isotropic antiferromagnetic SU(N) spin chains using the real space renormalization group. We find that they are governed at low energies by a universal infinite randomness fixed point different from the one of random spin-1/2 chains. We determine analytically the important exponents: the energy-length scale relation is $Ω\sim\exp(-L^ψ)$, where $ψ=1/N$, and the mean correlation function is given by $\bar{C_{ij}}\sim(-1)^{i-j}/|i-j|^ϕ$, where $ϕ=4/N$. Our analysis shows that the infinite-N limit is unable to capture the behavior obtained at any finite N.