Shot noise in magnetic tunnel junctions: e ffect of the geometric phase

by Alexander Shnirman

at Condensed Matter Theory Seminar

Wed, 16 Dec 2015, 13:30
Physics building (#54) room 207

Abstract

We analyze a current driven dynamics of magnetization and voltage in a magnetic tunnel junction As predicted in 1 2 the magnetization can be driven by spin currents This effect can also be reversed such that an externally driven magnetization generates a dc voltage 3 Although both effects are intimately related so far they have been treated separately We generalize the approach of 4 to derive an action that contains both effects simultaneously We employ the Keldysh formalism which allows us to derive stochastic Landau Lifshitz Gilbert Langevin equations describing the angular dynamics of the magnetization coupled with the voltage dynamics We predict that at low temperatures two different fluctuation regimes exist In one regime the voltage fluctuations are governed by the applied current only shot noise whereas in the other regime an excess noise governed by the geometric phase of the magnetization arises 1 L Berger Phys Rev B 54 9353 1996 2 J C Slonczewski J Magn Magn Mater 159 L1 1996 3 L Berger Phys Rev B 59 11465 1998 4 A Shnirman Y Gefen A Saha I S Burmistrov M N Kiselev and A Altland Phys Rev Lett 114 176806 2015

Created on 11-12-2015 by Bar Lev, Yevgeny (ybarlev)
Updaded on 11-12-2015 by Bar Lev, Yevgeny (ybarlev)