High-Field Electron Spin Resonance and Magnetization in the Dimerized Phase ofCuGeO3

Abstract

ESR and magnetization measurements have been performed up to 14 T in the compound ${\mathrm{CuGeO}}_3$. Two kinds of magnetic transitions are observed, between excited states and from the ground state. The former result essentially from a Zeeman splitting of the $S=1\mathrm{}$ magnetic triplet state characterizing the spin Peierls gap which exists at the wave vector $\mathbf{Q}=[1,1,1]\mathrm{}$ of the magnetic Brillouin zone. The latter provide the first evidence of a Zeeman splitting on a spin Peierls gap. It is observed at $\mathbf{Q}=[0,0,0]\mathrm{}$.