Noise in tunneling spin current across coupled quantum spin chains

Abstract

We theoretically study the spin current and its dc noise generated between two spin-1/2 spin chains weakly coupled at a single site in the presence of an over-population of spin excitations and a temperature elevation in one subsystem relative to the other, and compare the corresponding transport quantities across two weakly coupled magnetic insulators hosting magnons. In the spin chain scenario, we find that applying a temperature bias exclusively leads to a vanishing spin current and a concomitant divergence in the spin Fano factor, defined as the spin current noise-to-signal ratio. This divergence is shown to have an exact analogy to the physics of electron scattering between fractional quantum Hall edge states and not to arise in the magnon scenario. We also reveal a suppression in the spin current noise that exclusively arises in the spin chain scenario due to the fermion nature of the spin-1/2 operators. We discuss how the spin Fano factor may be extracted experimentally via the inverse spin Hall effect used extensively in spintronics.

12 pages, 8 figures

References in corpus (10)

• Observation of spin current in quantum spin liquid
• Transport equations for a two-dimensional electron gas with spin-orbit interaction
• Influence of yttrium iron garnet thickness and heater opacity on the nonlocal transport of electrically and thermally excited magnons
• Spin pumping and shot noise in ferrimagnets: bridging ferro- and antiferromagnets
• Spin Hall phenomenology of magnetic dynamics
• Spin-torque shot noise in magnetic tunnel junctions
• Spin-Flip Noise in a Multi-Terminal Spin-Valve
• Quantum critical dynamics of a S = 1/2 antiferromagnetic Heisenberg chain studied by 13C-NMR spectroscopy
• Shot Noise Induced by Nonequilibrium Spin Accumulation
• Spin Hall noise