  Magnetic properties of DNA liquid-crystal dispersions are experimentally
investigated by SQUID magnetometer. The magnetic susceptibility of pure DNA and
DNA doped by La, and Gd is measured in the region 4.2-300 K. The total magnetic
moment is represented as a sum of: the paramagnetic part and negative
diamagnetic part. The number of paramagnetic Gd3+ ions is calculated in a good
agreement with the number of phosphate complexes. The temperature dependence of
magnetic susceptibility indicates the presence of interaction between Gd3+
magnetic moments, which is discussed in terms of long-range RKKY-type exchange
in one-dimensional metals.
