Theory of a.c. spin current noise and spin conductance through a quantum dot in the Kondo regime I: The equilibrium case

Abstract

We analyze the equilibrium frequency-dependent spin current noise and spin conductance through a quantum dot in the local moment regime. Spin current correlations behave markedly differently from charge correlations. Equilibrium spin correlations are characterized by two universal scaling functions in the absence of an external field: one of them is related to charge correlations, while the other one describes cross-spin correlations. We characterize these functions using a combination of perturbative and non-perturbative methods. We find that at low temperatures spin cross-correlations are suppressed at frequencies below the Kondo scale, $T_K$, and a dynamical spin accumulation resonance is found at the Kondo energy, $\omega \sim T_K$. At higher temperatures, $T>T_K$, surprising low-frequency anomalies related to overall spin conservation appear in the spin noise and spin conductance, and the Korringa rate is shown to play a distinguished role. The transient spin current response also displays universal and singular properties.

17 pages, 15 figures

References in corpus (13)

• The numerical renormalization group method for quantum impurity systems
• Coherent control of a single electron spin with electric fields
• Kondo effect in quantum dots
• Using a quantum dot as a high-frequency shot noise detector
• Tunable Noise Cross-Correlations in a Double Quantum Dot
• Noisy Kondo impurities
• Dynamics of Quantum Noise in a Tunnel Junction under ac Excitation
• Density matrix numerical renormalization group for non-Abelian symmetries
• Ballistic Spin Resonance
• Shot noise in transport through "double quantum dots"
• Electrical generation of pure spin currents in a two-dimensional electron gas
• Observation of second-harmonic generation induced by pure spin currents
• Geometrical spin dephasing in quantum dots

Cited by in corpus (8)

• Effect of exchange interaction on the spin fluctuations of localized electrons
• Tunable spin/charge Kondo effect at a double superconducting island connected to two spinless quantum wires
• Transport in a hybrid normal-topological superconductor Kondo model
• Finite-frequency thermoelectric response in strongly correlated quantum dots
• Spin-resolved dynamical conductance of correlated large-spin magnetic molecules
• Signatures of Kondo-Majorana interplay in ac response
• Dynamical spin accumulation in large-spin magnetic molecules
• Spin versus charge noise from Kondo traps