Abstract
The authors study the thermodynamics of a 2D electron system in a strong magnetic field H within the framework of the 1/H expansion. A general expression for the partition function including corrections up to the second order in 1/H is obtained. This result is used for the evaluation of the shear modulus of the 2D electron crystal and of the magnetic moment of the electron system in the high-H limit. The density of states in the random long-ranged potential is also discussed.