Space dispersion feature of the conduction electron spin resonance in two-dimensional electron systems caused by the absence of 'up-down' symmetry

Abstract

The conduction electron spin resonance (CESR) in two-dimensional (2D) electron systems (inversion layers of semiconductor heterostructures and quantum wells) without 'up-down' symmetry is considered. The pyroelectric-like symmetry of such a layer makes a difference between two normals to the layer and thus leads to the 2D-electron Hamiltonian which includes an additional spin-orbit term H_so=( alpha /h(cross))(p*c). sigma where c is the vector of one of the non-equivalent normals. Accurate quantum kinetic theory with regard for the spin-orbit energy is proposed for the first time, and the paramagnetic linear response is evaluated. It is shown that, if the CESR is excited by a wave of wavevector q, then the decay rate should include a term which reverses its sign with an applied magnetic field B reversal and, for B parallel to the plane of electron motion, is given by Gamma =(h(cross)/ tau )(3( alpha p_F tau /h(cross)²)²+¹/₂(v_F tau q)²+2 alpha mv_F² tau ²h(cross)^-2q.(c*B)) where tau is the mean collision time and v_F is the Fermi velocity. An estimate for the effect in some semiconductor heterostructures is presented, and possibilities of experimental observation are briefly discussed.