ar X iv : c on d - m at / 9 60 50 76 v 1 1 2 M ay 1 99 6 Orbital Magnetism of 2 D Chaotic Lattices

We study the orbital magnetism of 2D lattices with chaotic motion of electrons withing a primitive cell. Using the temperature diagrammatic technique we evaluate the averaged value and rms fluctuation of magnetic response in the diffusive regime withing the model of non-interacting electrons. The fluctuations of magnetic susceptibility turn out to be large and at low temperature can be of the order of χ L (k F l) 3/2 , where k F is the Fermi wavevector, l is the mean free path, and χ L is the Landau susceptibility. In the certain region of magnetic fields the paramagnetic contribution to the averaged response is field independent and larger than the absolute value of Landau response. In the recent years, the orbital magnetism of mesoscopic systems has attracted much attention [1–3]. In the limit of the classically weak magnetic field, when the cyclotron radius is larger than the electron mean free path, the structure of energy levels of mesoscopic sample is very sensitive to the impurity configuration. As a result, the fluctuations of magnetic response turn out to be larger than the disorder-averaged value, i.e., the magnetic response of mesoscopic metallic sample has a random sign as a function of impurity configuration. This makes the investigation of sample-specific fluctuations to be of great importance for the understanding of the orbital magnetism of mesoscopic systems. In the work of Oh et al. [1] the most attention was paid to the extreme quantum coherence