Magnetic susceptibility of exchange-disordered antiferromagnetic finite chains

The low-temperature behavior of the static magnetic susceptibility of exchange-disordered antiferromagnetic spin chains is investigated. It is shown that for a relatively small and even number of spins in the chain, two exchange distributions which are expected to occur in nanochains of P donors in silicon lead to quite distinct low-temperature susceptibility behavior. As a consequence, magnetic measurements might be useful to characterize whether a given sample meets requirements compatible with Kane's original proposal for the exchange gates in a silicon-based quantum computer hardware.