Effects of Transverse Magnetic Anisotropy on Current-Induced Spin Switching

Misiorny, Maciej; Barnaś, J.

doi:10.1103/physrevlett.111.046603

Cited by 25 publications

(20 citation statements)

References 50 publications

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“…This high sensitivity to the bias has been discussed in Ref. [48] for intrinsic anisotropy, see in particular Fig. 2 of that reference (compare black dashed and solid lines of the bottom plots).…”

Section: F Spin-filtering Effectsupporting

confidence: 68%

“…The non-linear conductance is obtained using the leading order perturbation theory (Fermi golden rule) and a master equation, for details see Refs. [46][47][48]. In Fig.…”

Section: Identification Of Quadrupolar Term From Transport Spectramentioning

confidence: 96%

“…In general, at zero magnetic field the presence of fixed magnetic anisotropy (D = 0) manifests as a splitting of the Kondo resonance 41,42 into peaks at the renormalized, finite excitation energies with logarithmic enhancements 40,43,44 . For larger values of D the remnants of the split Kondo peak evolve into inelastic cotunneling steps with slight non-equilibrium overshooting at the step-edge 35,[45][46][47][48] . It was noted experimentally in Ref.…”

Section: Identification Of Quadrupolar Term From Transport Spectramentioning

confidence: 99%

See 2 more Smart Citations

Spintronic magnetic anisotropy

2013

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An attractive feature of magnetic adatoms and molecules for nanoscale applications is their superparamagnetism, the preferred alignment of their spin along an easy axis preventing undesired spin reversal. The underlying magnetic anisotropy barrier -a quadrupolar energy splitting -is internally generated by spin-orbit interaction and can nowadays be probed by electronic transport. Here we predict that in a much broader class of quantum-dot systems with spin larger than one-half, superparamagnetism may arise without spin-orbit interaction: by attaching ferromagnets a spintronic exchange field of quadrupolar nature is generated locally. It can be observed in conductance measurements and surprisingly leads to enhanced spin filtering even in a state with zero average spin. Analogously to the spintronic dipolar exchange field, responsible for a local spin torque, the effect is susceptible to electric control and increases with tunnel coupling as well as with spin polarization.The growing interest in nanomagnets, e.g., magnetic adatoms 1 and single-molecule magnets 2 is fueled by prospects of their application in novel spintronic devices whose functionality derives from their unique magnetic features 3 . A key property of such systems is their strong magnetic anisotropy leading to magnetic bistability, required for building blocks for nanoscale memory cells 4,5 and non-trivial quantum dynamics, useful for quantum information processing 6,7 . In either case, operational stability of such devices hinges heavily on the height of the energy barrier opposing the spin reversal. Though recently progress in the control over the magnetic anisotropy by synthesis 8 , mechanical straining 9 , atomic manipulation 10 or electrical gating 11 has been made, achieving of a high spin-reversal barrier still remains a challenge. Incorporating a nanomagnet into an electronic circuit may significantly alter its magnetic properties [12][13][14] , but may also be advantageous. One possible, spintronic route for manipulation of nanomagnets entails ferromagnetic electrodes and uses the spin torque due to spin-polarized scattering 15 or Coulomb interaction 16 , magnetic analogs of the proximity effect in superconducting junctions. In this article, we present another route that combines spintronics with molecular magnetism: high-spin quantum dots can acquire a significant magnetic anisotropy that is purely of spintronic origin, instead of deriving from the spin-orbit interaction, as the tunneling to ferromagnets induces a local, quadrupolar exchange field. Besides providing an alternative approach to electrical manipulation and engineering of superparamagnetic nanomagnets, this new quantity is of key importance for the analysis of experiments that probe atoms or molecules using highly spin-polarized electrodes. DIPOLAR VS. QUADRUPOLAR EXCHANGE FIELDThe origin of superparamagnetism, usually dominating the magnetic behaviour of a nanomagnet, is a magnetic anisotropy energy barrier. For instance, an adatom with a spin-degenerate ground multiplet (q...

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Section: F Spin-filtering Effectsupporting

confidence: 68%

“…The non-linear conductance is obtained using the leading order perturbation theory (Fermi golden rule) and a master equation, for details see Refs. [46][47][48]. In Fig.…”

Section: Identification Of Quadrupolar Term From Transport Spectramentioning

confidence: 96%

Section: Identification Of Quadrupolar Term From Transport Spectramentioning

confidence: 99%

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Spintronic magnetic anisotropy

2013

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“…Recent studies have demonstrated that the presence of nonzero transverse anisotropy modifies the switching frequency of few-atom magnets when atoms are directly adsorbed on the substrate [7]. It has also been predicted that finite values of transverse anisotropy lead to the appearance of peaks in the differential conductance when using spin-polarized STM [21], and a recent experiment has demonstrated that the strength of the magnetocrystalline anisotropy can be controllably enhanced or reduced by manipulating its local strain environment [22]. In addition, ferromagnetically coupled atomic chains (nanomagnets) usually exhibit non-negligible values of transverse anisotropy [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Effect of transverse anisotropy on inelastic tunneling spectroscopy of atomic-scale magnetic chains

Hageman¹,

Blaauboer

2017

Phys. Rev. B

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We theoretically investigate the effect of transverse magnetic anisotropy on spin-flip assisted tunneling through atomic-spin chains. Using a phenomenological approach and first-order perturbation theory, we analytically calculate the inelastic tunneling current, differential conductance, and atomic-spin transition rates. We predict the appearance of additional steps in the differential conductance and a pronounced increase in the spin-flip transition rate which at low voltages scales quadratically with the ratio of the transverse anisotropy energy and the sum of the longitudinal anisotropy energy and the exchange energy. Our results provide intuitive qualitative insight into the role played by transverse anisotropy in inelastic tunneling spectroscopy of atomic chains and can be observed under realistic experimental conditions.

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“…Crystals of SMMs have drawn attention due to unique quantum properties such as quantum tunneling of magnetization 1,2 and quantum interference or Berry-phase oscillations induced by the magnetic anisotropy [4][5][6] . There have been studies of the interplay between the quantum properties and the electron transport of individual SMMs at the single-molecule level [7][8][9][10][11][12][13][14][15][16][17][18][19] .…”

Section: Introductionmentioning

confidence: 99%

Electron-vibron coupling effects on electron transport via a single-molecule magnet

et al. 2015

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We investigate how the electron-vibron coupling influences electron transport via an anisotropic magnetic molecule, such as a single-molecule magnet (SMM) Fe 4 , by using a model Hamiltonian with parameter values obtained from density-functional theory (DFT). Magnetic anisotropy parameters, vibrational energies, and electron-vibron coupling strengths of the Fe 4 are computed using DFT. A giant spin model is applied to the Fe 4 with only two charge states, specifically a neutral state with the total spin S = 5 and a singly charged state with S = 9/2, which is consistent with our DFT result and experiments on Fe 4 single-molecule transistors. In sequential electron tunneling, we find that the magnetic anisotropy gives rise to new features in conductance peaks arising from vibrational excitations. In particular, the peak height shows a strong, unusual dependence on the direction as well as magnitude of applied B field. The magnetic anisotropy also introduces vibrational satellite peaks whose position and height are modified with the direction and magnitude of applied B field. Furthermore, when multiple vibrational modes with considerable electron-vibron coupling have energies close to one another, a low-bias current is suppressed, independently of gate voltage and applied B field, although that is not the case for a single mode with the similar electron-vibron coupling. In the former case, the conductance peaks reveal a stronger B-field dependence than in the latter case. The new features appear because the magnetic anisotropy barrier is of the same order of magnitude as the energies of vibrational modes with significant electron-vibron coupling. Our findings clearly show the interesting interplay between magnetic anisotropy and electron-vibron coupling in electron transport via the Fe 4 . The similar behavior can be observed in transport via other anisotropic magnetic molecules.

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Effects of Transverse Magnetic Anisotropy on Current-Induced Spin Switching

Cited by 25 publications

References 50 publications

Spintronic magnetic anisotropy

Spintronic magnetic anisotropy

Effect of transverse anisotropy on inelastic tunneling spectroscopy of atomic-scale magnetic chains

Electron-vibron coupling effects on electron transport via a single-molecule magnet

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