Enhanced spin interactions in digital magnetic heterostructures

A new heterostructure is developed in which fractional monolayers of magnetic ions are introduced "digitally" within a semiconductor quantum well. Rearranging moments within two-dimensional (2D) planes provides additional control over their interactions, yielding tunable two-level electronic systems in which spin splittings are significantly larger than inhomogeneous linewidths in modest magnetic fields. Femtosecond-resolved electronic and magnetic spectroscopies reveal spin-flip scattering dependent only on the Zeeman energy but not the local magnetic environment, and long-lived dynamic magnetizations.