A spin logic device which includes an electron confinement layer confining an electron gas in a two-dimensional area (2DEG) subtended by a direction x and a direction y, the latter perpendicular to the former. The spin logic device is configured for the 2DEG to support a persistent spin helix (PSH) formed therein with a given spin component oscillating with periodicity λ along direction x but not oscillating along direction y. Majority logic circuit of the spin logic device includes: at least one input device energizable to create respective local spin-polarizations of the 2DEG in first regions of the confinement layer. The input device is configured to detect in a second region of the confinement layer an average spin-polarization of the 2DEG diffused through resulting PSHs, wherein a projection of a distance between the second region and first regions onto direction x is equal to nλ/a, n integer, a equal to 2 or 4.