Voltage-induced conversion of helical to uniform nuclear spin polarization in a quantum wire

Kornich, Viktoriia; Stano, Peter; Zyuzin, A. A.; Loss, Daniel

doi:10.1103/physrevb.91.195423

Cited by 9 publications

(13 citation statements)

References 45 publications

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“…As discussed in the literature, these include: (1) the reduction of conductance by a factor of 2 due to the opening of the partial gap; 37,38,47,112 (2) the anisotropic spin susceptibilityχ x αβ (q) =χ z αβ (q) due to the formation of the nuclear spin order; 95 (3) NMR response at the frequency set by the RKKY exchange due to the singular RKKY peak; 113 (4) the unusual temperature dependence of the nuclear spin relaxation rate due to the Luttinger liquid parameters modified by the Overhauser field; 114 (5) the reentrant behavior in the conductance as a function of gate voltage due to the nuclear spin induced gap; 115 (6) the dynamical nuclear polarization at zero external magnetic field. 42 Furthermore, experimental probes can be implemented to observe the distinct pairing gaps, ∆ (e/i) s…”

Section: Discussionmentioning

confidence: 99%

Antiferromagnetic nuclear spin helix and topological superconductivity inC13nanotubes

et al. 2015

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We investigate the RKKY interaction arising from the hyperfine coupling between localized nuclear spins and conduction electrons in interacting 13 C carbon nanotubes. Using the Luttinger liquid formalism, we show that the RKKY interaction is sublattice dependent, consistent with the spin susceptibility calculation in noninteracting carbon nanotubes, and it leads to an anti-ferromagnetic nuclear spin helix in finite-size systems. The transition temperature reaches up to tens of millikelvins, due to a strong boost by a positive feedback through the Overhauser field from ordered nuclear spins. Similar to GaAs nanowires, the formation of the helical nuclear spin order gaps out half of the conduction electrons, and is therefore observable as a reduction of conductance by a factor of two in a transport experiment. The nuclear spin helix leads to a density wave combining spin and charge degrees of freedom in the electron subsystem, resulting in synthetic spin-orbit interaction, which induces non-trivial topological phases. As a result, topological superconductivity with Majorana fermion bound states can be realized in the system in the presence of proximity-induced superconductivity without the need of fine tuning the chemical potential. We present the phase diagram as function of system parameters, including the pairing gaps, the gap due to the nuclear spin helix, and the Zeeman field perpendicular to the helical plane.

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Section: Discussionmentioning

confidence: 99%

Antiferromagnetic nuclear spin helix and topological superconductivity inC13nanotubes

et al. 2015

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“…Here σ µ denotes the µ component of the Pauli matrix vector in spin space. We take the nuclear density to be ρ nuc = 8/a 3 0 with the lattice constant a 0 [61,62], and write the electron operator Ψ el as the product of the transverse (x ⊥ ) and the longitudinal (r) parts,…”

Section: Hamiltonianmentioning

confidence: 99%

“…Before moving to the magnon-mediated backscattering, let us comment on two complications not considered in this work. First, we remark that an applied voltage may lead to the nuclear spin polarization along the spin quantization (z) axis [31,62,64], and thus modify the nuclear spin order. While the z component of the nuclear spin polarization does not directly cause the spin-flip backscattering, it reduces the xy components of the Overhauser field from B Ov to B Ov 1 − P 2 N (T ), with a temperature-dependent factor, P N (T ).…”

Section: A Impurity-induced Resistance In the Ordered Phasementioning

confidence: 99%

Effects of nuclear spins on the transport properties of the edge of two-dimensional topological insulators

et al. 2018

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The electrons in the edge channels of two-dimensional topological insulators can be described as a helical Tomonaga-Luttinger liquid. They couple to nuclear spins embedded in the host materials through the hyperfine interaction, and are therefore subject to elastic spin-flip backscattering on the nuclear spins. We investigate the nuclear-spin-induced edge resistance due to such backscattering by performing a renormalization-group analysis. Remarkably, the effect of this backscattering mechanism is stronger in a helical edge than in nonhelical channels, which are believed to be present in the trivial regime of InAs/GaSb quantum wells. In a system with sufficiently long edges, the disordered nuclear spins lead to an edge resistance which grows exponentially upon lowering the temperature. On the other hand, electrons from the edge states mediate an anisotropic Ruderman-Kittel-Kasuya-Yosida nuclear spin-spin interaction, which induces a spiral nuclear spin order below the transition temperature. We discuss the features of the spiral order, as well as its experimental signatures. In the ordered phase, we identify two backscattering mechanisms, due to charge impurities and magnons. The backscattering on charge impurities is allowed by the internally generated magnetic field, and leads to an Anderson-type localization of the edge states. The magnon-mediated backscattering results in a power-law resistance, which is suppressed at zero temperature. Overall, we find that in a sufficiently long edge the nuclear spins, whether ordered or not, suppress the edge conductance to zero as the temperature approaches zero.

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“… 16 . This initial condition is evidenced by recent high polarization experiments in quantum hall edge states 41 ( ) and a bias voltage in a ballistic quantum wire 42 ( ). Additionally, the fully polarized nuclei have been proposed as the storage of an electron spin state 19 .…”

Section: Methodsmentioning

confidence: 80%

Decoherence and control of a qubit in spin baths: an exact master equation study

Jing

2018

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In spin-based nanosystems for quantum information processing, electron spin qubits are subject to decoherence due to their interactions with nuclear spin environments. In this paper, we present an exact master equation for a central spin-1/2 system in time-dependent external fields and coupled to a spin-half bath in terms of hyperfine interaction. The master equation provides a unified description for free and controlled dynamics of the central spin and is formally independent of the details and size of spin environments. Different from the previous approaches, the master equation remains exact even in the presence of external control fields. Using the parameters for realistic nanosystems with nonzero nuclear spins, such as GaAs, we investigate the Overhauser’s effect on the decoherence dynamics of the central spin under different distributions of bath-spin frequencies and system-bath coupling strengths. Furthermore, we apply the leakage elimination operator, in a nonperturbative manner, to this system to suppress the decoherence induced by hyperfine interaction.

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Voltage-induced conversion of helical to uniform nuclear spin polarization in a quantum wire

Cited by 9 publications

References 45 publications

Antiferromagnetic nuclear spin helix and topological superconductivity inC13nanotubes

Antiferromagnetic nuclear spin helix and topological superconductivity inC13nanotubes

Effects of nuclear spins on the transport properties of the edge of two-dimensional topological insulators

Decoherence and control of a qubit in spin baths: an exact master equation study

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