6533b856fe1ef96bd12b28f4
RESEARCH PRODUCT
Spin Pumping and Torque Statistics in the Quantum Noise Limit
Pauli VirtanenTero T. Heikkiläsubject
FOS: Physical sciencesGeneral Physics and Astronomy02 engineering and technologyMagnetization01 natural sciencesspin pumpingQuantum mechanicsMesoscale and Nanoscale Physics (cond-mat.mes-hall)0103 physical sciencesStatistics010306 general physicsMagnetic anisotropySpin-½PhysicsSpin pumpingStochastic systemsCondensed Matter - Mesoscale and Nanoscale Physicsta114SpintronicsCondensed matter physicsQuantum limitQuantum noiseSpin-transfer torqueCharge (physics)Condensed Matter::Mesoscopic Systems and Quantum Hall Effect021001 nanoscience & nanotechnologyNanomagnetTorquequantum noise limit0210 nano-technologytorque statisticsEnergy (signal processing)description
We analyze the statistics of charge and energy currents and spin torque in a metallic nanomagnet coupled to a large magnetic metal via a tunnel contact. We derive a Keldysh action for the tunnel barrier, describing the stochastic currents in the presence of a magnetization precessing with the rate $\Omega$. In contrast to some earlier approaches, we include the geometric phases that affect the counting statistics. We illustrate the use of the action by deriving spintronic fluctuation relations, the quantum limit of pumped current noise, and consider the fluctuations in two specific cases: the situation with a stable precession of magnetization driven by spin transfer torque, and the torque-induced switching between the minima of a magnetic anisotropy. The quantum corrections are relevant when the precession rate exceeds the temperature $T$, i.e., for $\hbar \Omega \gtrsim k_B T$.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2016-09-15 | Physical Review Letters |