Nuclear-spin relaxation in two-dimensional metals at high magnetic fields: Hg3-δAsF6

An unusual linear dependence of the nuclear-spin relaxation rate upon the magnetic field is observed in the incommensurate linear-chain mercury compound Hg3-δAsF6. It is shown that in two-dimensional metals the planar cyclotron motion of the conduction electrons in a strong magnetic field gives rise to a divergence of the spin-spin correlation function. This new effect, combined with the small orbits resulting from the incommensurate structure, can explain the observed nuclear-spin relaxation behavior in the pseudo two-dimensional metal Hg3-δAsF6.