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arXiv · 0707.0062

Magnetic Single-Electron Transistor as a Tunable Model System for Kondo-Destroying Quantum Criticality

Stefan Kirchner·Qimiao Si
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Abstract

Single-electron transistors attached to ferromagnetic leads can undergo a continuous quantum phase transition as their gate voltage is tuned. The corresponding quantum critical point separates a Fermi liquid phase from a non-Fermi liquid one. Here, we expound on the physical idea proposed earlier. The key physics is the critical destruction of the Kondo effect, which underlies a new class of quantum criticality that has been argued to apply to heavy fermion metals. Its manifestation in the transport properties is studied through an effective Bose-Fermi Kondo model; the bosonic bath, corresponding to the spin waves of the ferromagnetic leads, describes a particular type of sub-Ohmic dissipation. We also present results for general forms of sub-Ohmic dissipative bath, and consider in some detail the case with critical paramagons replacing spin waves. Finally, we discuss some delicate aspects in the theoretical treatment of the effect of a local magnetic field, particularly in connection with the frequently employed Non-Crossing Approximation.

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Stefan Kirchner, Qimiao Si. 2007-08-20. Magnetic Single-Electron Transistor as a Tunable Model System for Kondo-Destroying Quantum Criticality. https://doi.org/10.1016/j.physb.2007.10.297

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