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arXiv · 2104.00565

Response tensor for a spin-dependent electron gas: dependence on the choice of spin operator

Victor. M. Demcsak·Donald. B. Melrose
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Abstract

It is shown that the choice of spin-operator affects the form of the response tensor describing a spin-dependent electron gas. The covariant, spin-dependent response tensor for a magnetic dipole moment-polarized electron gas (statistical distribution of electrons and positrons) is evaluated. A simultaneous eigenfunction of both the magnetic-moment spin-operator and the Dirac Hamiltonian is constructed, from which explicit expressions for the magnetic-moment states and the corresponding vertex functions are derived. It is shown that a gas of electrons having a preferred magnetic-moment spin has a rotatory-type response that is gyrotropic. In contrast, when the helicity is chosen as the spin operator, the response of an electron gas with a preferred helicity spin has a rotatory response that is analogous to an optically active medium. The distinction between these spin operators does not appear in conventional treatments of spin-dependence in quantum plasmas.

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Victor. M. Demcsak, Donald. B. Melrose. 2021-03-05. Response tensor for a spin-dependent electron gas: dependence on the choice of spin operator. https://doi.org/10.1103/physreve.103.l061201

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