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Spin dynamics of a hopping carrier in a random hyperfine field
May 5, 20174:00 pm – 5:00 pm (CDT)

Spin dynamics of a hopping carrier in a random hyperfine field


Mikhail Raikh (University of Utah)


Ar. Abanov



Mitchell Institute for Fundamental Physics & Astronomy

College Station, Texas 77843

Event Details

In course of carrier motion between the sites which host random hyperfine fields, its spin experiences random precessions. Normally, this leads to the exponential decay of average spin, , with a rate proportional to the square of the magnitude of the field. We demonstrate that in low dimensions, d = 1, 2, this orthodox scenario is violated: the decay does not follow the simple-exponent behavior at all times. The origin of the effect is that for d = 1, 2 a typical random-walk trajectory exhibits numerous self-intersections. Multiple visits of the carrier to the same site accelerates the relaxation since the corresponding partial rotations of spin during these visits add up. Another consequence of self -intersections of the random-walk trajectories is that, in all dimensions, becomes sensitive to a weak magnetic field directed along z-axis. Remarkably, for random fields located in the (x, y) - plane, the decay of in d = 1 is accompanied by the reversal. We develop an approximate analytical description of the behavior. This description is in a very good agreement with numerical simulations.

* In collaboration with Yue Zhang, Robert Roundy, and Vagharsh Mkhitaryan

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