Cotunneling mechanism for all-electrical electron spin resonance of single adsorbed atoms

Gálvez, J. Reina; Wolf, Christoph; Delgado, Fernando; Lorente, Nicolás

doi:10.1103/physrevb.100.035411

Cited by 30 publications

(18 citation statements)

References 45 publications

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“…[29] Further experimental and theoretical studies, however, show that this mechanism is typically weaker than the aforementioned driving through the tip's magnetic field gradient [60] and cannot explain experimental results such as ESR driving of spin-1/2 atoms. [35,36] In an interesting proposal of a cotunneling driving mechanism, [93] the RF electric field periodically modifies the hopping amplitude between the surface atom and a metallic reservoir, resulting in an oscillating driving term after tracing out the reservoir's degrees of freedom. Other proposals rely on spin-transfer torque induced by spin-polarized tunnel current, [94] RF modulation of the tunnel barrier, [95] A strong, local RF magnetic field (i-iii) can be generated by combining an RF electrical field across the tunnel junction (applied to the tip or an antenna) with a spatially-varying static magnetic field (from a magnetic tip or a nearby single-atom magnet).…”

Section: Single Spin Control In Esr-stm and Its Mechanismmentioning

confidence: 99%

Harnessing the Quantum Behavior of Spins on Surfaces

2022

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out via microwave photons. [4] Spins in solid-state materials constitute another family of individual quantum systems where spin states with naturally quantized energy levels can be manipulated via magnetic fields. Physical realizations of solidstate spin systems include gate-defined quantum dots, single dopants in semiconductors such as phosphorus donors in silicon, and single defects in insulators such as nitrogen-vacancy centers in diamond. [5][6][7] Harnessing quantum resources at the nanoscale gives birth to the discipline of quantum-coherent nanoscience that may bring forth useful quantum nanodevices "at the bottom." [8,9] In this review, we focus on a new class of quantum spin systems, individual atomic and molecular spins on surfaces, which has the potential to produce quantum functionalities at the atomic scale. An STM is used to access this tiny length scale, where a sharp metallic tip is positioned in nanometer proximity to spin carriers on a surface to probe their properties through tunneling electrons. [10] Experiments with single atomic spins on material surfaces date back to the early days of low-temperature STM, when Yu-Shiba-Rusinov states and a Kondo resonance were measured in individual magnetic atoms on bulk superconductors [11] and noble metals, [12,13] respectively. STM has also been extensively used on single molecular spins to characterize molecular structures, [14][15][16] probe and modify their electronic and magnetic properties, [17][18][19] and investigate their classical and quantum applications. [19][20][21] Following early STM experiments on single spins, the desire to further control and magnetically image individual spins has prompted the developments of new local probe techniques such as spinpolarized STM, [22] inelastic-tunneling-based spin-flip spectroscopy, [23] electrical pump-probe measurements, [24] and various innovative forms of force and magnetic microscopy. [25][26][27][28] An exciting development in recent years is the incorporation of coherent spin control in atomic-scale microscopy. The need to coherently manipulate and measure individual spins at this length scale necessitates all-electrical protocols with Angstrom precision. These stringent requirements are met by drawing on powerful methodologies from material and quantum sciences, that is, STM's abilities to build nanostructures atom-by-atom and selectively sense individual spin-carrying atoms, as well as electron spin resonance's (ESR's) ability to coherently control electron spin states via electromagnetic waves. This unique combination has so far enabled the quantum control of single electron spins of atoms [29][30][31][32][33] and molecules, [34] as well as the manipulation of single nuclear spins through hyperfine interactions. [35] Quantum coherence can be increased using singlet-triplet The desire to control and measure individual quantum systems such as atoms and ions in a vacuum has led to significant scientific and engineering developments in the past decades that form the basis of today's quantum infor...

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Section: Single Spin Control In Esr-stm and Its Mechanismmentioning

confidence: 99%

Harnessing the Quantum Behavior of Spins on Surfaces

2022

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“…The crystal and ligand field contribution in ionic environments is frequently described in terms of point charges . Although this approach does not provide a general good quantitative description, it is often used as a fitting procedure to electron spin resonance spectra (ESR), and we have successfully used it to model the STM-ESR on a single Fe atom on MgO . Here, we take an alternative approach that goes beyond the point-charge description by including covalent bonding.…”

Section: Methodsmentioning

confidence: 99%

Efficient Ab Initio Multiplet Calculations for Magnetic Adatoms on MgO

et al. 2020

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Scanning probe microscopy and spectroscopy, and more recently in combination with electron spin resonance, have allowed the direct observation of electron dynamics on the single-atom limit. The interpretation of data is strongly depending on model Hamiltonians. However, fitting effective spin Hamiltonians to experimental data lacks the ability to explore a vast number of potential systems of interest. By using plane-wave density functional theory (DFT) as starting point, we build a multiplet Hamiltonian making use of maximally-localized Wannier functions. The Hamiltonian contains spinorbit and electron-electron interactions needed to obtain the relevant spin dynamics. The resulting reduced Hamiltonian is solved by exact diagonalization. We compare three prototypical cases of 3d transition metals Mn (total spin S = 5/2), Fe (S = 2) and Co (S = 3/2) on MgO with experimental data and find that our calculations can accurately predict the spin orientation and anisotropy of the magnetic adatom. Our method does not rely on experimental input and permits us to explore and predict the fundamental magnetic properties of adatoms on surfaces.arXiv:1912.09793v1 [cond-mat.mes-hall]

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“…Larger values of have been achieved using ESR-STM, where several different driving mechanisms other than the Zeeman interaction with the ac field have been proposed [41][42][43][44]. For Ti-H on MgO, and an S = 1/2 spin system, ac magnetic fields up to 1 mT have been reported [40], with an induced Rabi frequency /2π ∼ 10 MHz in continuous mode, while Rabi frequencies up to 30 MHz have been demonstrated in pulsed ESR-STM [45] or using double resonance under large ac voltages [46].…”

Section: Estimate Of Maximal DC Currentmentioning

confidence: 99%

Electrically detected single-spin resonance with quantum spin Hall edge states

Delgado

Fernández-Rossier

2023

Phys. Rev. B

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Detection is most often the main impediment to reduce the number of spins in paramagnetic resonance experiments. Here, we propose another route to carry out electrically detected spin resonance of an individual spin, placed at the edge of a quantum spin Hall insulator (QSHI). The edges of a QSHI host a one-dimensional electron gas with perfect spin-momentum locking. Therefore, the spin relaxation induced by emission of an electron-hole pair at the edge state of the QSHI can generate current. Here, we demonstrate that driving the system with an ac signal, a nonequilibrium occupation can be induced in the absence of applied bias voltage, resulting in a dc measurable current. We compute the dc current as a function of the Rabi frequency , the spin relaxation, and decoherence times T 1 , and we discuss the feasibility of this experiment with state-of-the-art instrumentation.

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Cotunneling mechanism for all-electrical electron spin resonance of single adsorbed atoms

Cited by 30 publications

References 45 publications

Harnessing the Quantum Behavior of Spins on Surfaces

Harnessing the Quantum Behavior of Spins on Surfaces

Efficient Ab Initio Multiplet Calculations for Magnetic Adatoms on MgO

Electrically detected single-spin resonance with quantum spin Hall edge states

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