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 Hso=( 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 pF tau /h(cross)2)2+1/2(vF tau q)2+2 alpha mvF2 tau 2h(cross)-2q.(c*B)) where tau is the mean collision time and vF is the Fermi velocity. An estimate for the effect in some semiconductor heterostructures is presented, and possibilities of experimental observation are briefly discussed.