Justin K. Perron, Michael D. Stewart, Neil M. Zimmerman
Pauli-spin blockade is a phenomenon that allows for a type of spin to charge conversion often used to probe fundamental physics such as spin relaxation and singlet-triplet coupling. In this paper we theoretically explore Pauli-spin blockade as a function of parallel magnetic _eld B. In the well-studied low magnetic _eld regime, where PSB occurs in the (1; 1) ! (0; 2) tunneling direction, we highlight some aspects of PSB that are not discussed in detail in existing literature, including the change in size of bias triangles measured in both the forward and reverse biasing directions as a function of B. At higher _elds we predict a crossover to PSB in the reverse direction. In the high _eld PSB regime current is blockaded due to the occupation of a spin singlet as opposed to the traditional triplet blockade that occurs at low _elds. The onset of the high _eld, reverse PSB coincides with the development of a tail like feature in the measured bias triangles and occurs at the magnetic _eld, BST , where the Zeeman energy of the polarized triplet has the same magnitude as the exchange energy in the (0,2) charge con_guration. In Si quantum dots BST is expected to be experimentally accessible; thus, this work suggests a new way to probe interesting physics including singlet to triplet relaxation mechanisms when both electrons occupy the same quantum dot.