Magnetic friction: Towards the microscopic statistical description

Using Zubarev's Nonequilibrium Statistical Operator Method (NSOM), we outline a microscopic approach to the problem of magnetic friction in Magnetic Force Microscopy where a magnetic nanotip scans a surface of a solid magnetic sample. For the Stokes regime (small tip velocity), we construct the statistical operator describing nonequilibrium states of the composite system (sample plus tip) and calculate the magnetic friction force acting on the tip. The magnetic friction coefficients are expressed in terms of time-dependent quantum correlation functions of fluctuating tip-sample forces. Some possible generalizations of the formalism to high tip velocities are discussed. © 2018 Elsevier B.V.