Quantum transport through anisotropic molecular magnets: Hubbard Green function approach

Niu, Peng-Bin; Zhang, Yuying; Wang, Qiang; Nie, Yi-Hang

doi:10.1016/j.physleta.2012.03.007

Cited by 16 publications

(11 citation statements)

References 33 publications

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“…The non-equilibrium Green’s function method has been widely used in the discussion of Kondo effects in quantum dots 5 47 –5 1 . In order to handle the large spin involved in many problems, we use the Hubbard operator Green’s function method 34 , which has been used to solve the transport problems in the linear response, non-linear response, and Kondo regimes 52 53 54 . In this Hubbard operator representation, the electron operators in the dot are rewritten as with δ σ = +1(−1) for σ = ↑(↓), , s + = X ↑↓ and s − = X ↓↑ .…”

Section: Methodsmentioning

confidence: 99%

“…In the limit of infinite Coulomb interaction ( U → ∞), double-occupation is forbidden and c σ = X 0 σ . The large spin operators can be expressed as 34 , , and , with S representing the large spin quantum number and . Hence, the total Hamilton is rewritten as…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, we find a Kondo dip at the Fermi level under proper parameters. To evaluate the dot’s density of states and differential conductance, we use a non-equilibrium Hubbard operator Green’s function method 34 . To calculate the relevant Hubbard operator Green’s functions from the equations of motion, we apply the truncation scheme introduced in ref.…”

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confidence: 99%

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Kondo peak splitting and Kondo dip induced by a local moment

Niu

Shi

Sun

et al. 2015

Sci Rep

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Many features like spin-orbit coupling, bias and magnetic fields applied, and so on, can strongly influence the Kondo effect. One of the consequences is Kondo peak splitting. However, Kondo peak splitting led by a local moment has not been investigated systematically. In this research we study theoretically electronic transport through a single-level quantum dot exchange coupled to a local magnetic moment in the Kondo regime. We focus on the Kondo peak splitting induced by an anisotropic exchange coupling between the quantum dot and the local moment, which shows rich splitting behavior. We consider the cases of a local moment with S = 1/2 and S = 1. The longitudinal (z-component) coupling plays a role of multivalued magnetic fields and the transverse (x, y-components) coupling lifts the degeneracy of the quantum dot, both of which account for the fine Kondo peak splitting structures. The inter-level or intra-level transition processes are identified in detail. Moreover, we find a Kondo dip at the Fermi level under the proper parameters. The possible experimental observations of these theoretical results should deepen our understanding of Kondo physics.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Kondo peak splitting and Kondo dip induced by a local moment

Niu

Shi

Sun

et al. 2015

Sci Rep

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“…Non-equilibrium Hubbard Green function has been used to solve the thermoelectric transport in the sequential and linear response regime 35 . The system Hamilton can be rewritten by the transition operator 36 37 38 39 , i.e.…”

Section: Methodsmentioning

confidence: 99%

Ultrahigh spin thermopower and pure spin current in a single-molecule magnet

Luo

Liu

Lü

et al. 2014

Sci Rep

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Using the non-equilibrium Green's function (NEGF) formalism within the sequential regime, we studied ultrahigh spin thermopower and pure spin current in single-molecule magnet(SMM), which is attached to nonmagnetic metal wires with spin bias and angle (θ) between the easy axis of SMM and the spin orientation in the electrodes. A pure spin current can be generated by tuning the gate voltage and temperature difference with finite spin bias and the arbitrary angle except of . In the linear regime, large thermopower can be obtained by modifying Vg and the angles (θ). These results are useful in fabricating and advantaging SMM devices based on spin caloritronics.

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“…Thus it fails the usual second quantization EOM technique. Here, following our previous work, 26 we use the EOM technique combined with Hubbard operators. 27 The completeness basis of the OL is {|0 , |↑ , |↓ , |2 } and the electron operators in the OL are rewritten as d σ = X 0σ + δ σ X σ2 , with δ σ = + 1(1) for σ = ↑ (↓) and σ = −σ; the electron spin operators are written as s z = X ↑↑ − X ↓↓ /2, s + = X ↑↓ and s = X ↓↑ , where X ij = |i j| are defined in terms of electron basis states |i (|j ) (i, j = 0, ↑, ↓, 2) of the OL.…”

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confidence: 99%

Spin Seebeck effect in a metal-single-molecule-magnet-metal junction

Niu

Liu

et al. 2018

AIP Advances

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We investigate the nonlinear regime of temperature-driven spin-related currents through a single molecular magnet (SMM), which is connected with two metal electrodes. Under a large spin approximation, the SMM is simplified to a natural two-channel model possessing spin-opposite configuration and Coulomb interaction. We find that in temperature-driven case the system can generate spin-polarized currents. More interestingly, at electron-hole symmetry point, the competition of the two channels induces a temperature-driven pure spin current. This device demonstrates that temperature-driven SMM junction shows some results different from the usual quantum dot model, which may be useful in the future design of thermal-based molecular spintronic devices.

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Quantum transport through anisotropic molecular magnets: Hubbard Green function approach

Cited by 16 publications

References 33 publications

Kondo peak splitting and Kondo dip induced by a local moment

Kondo peak splitting and Kondo dip induced by a local moment

Ultrahigh spin thermopower and pure spin current in a single-molecule magnet

Spin Seebeck effect in a metal-single-molecule-magnet-metal junction

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