Magnetization Reversal of Individual Co Nanoislands

Ouazi, S.; Wedekind, Sebastian; Rodary, Guillemin; Oka, Hideki; Sander, Dirk; Kirschner, J.

doi:10.1103/physrevlett.108.107206

Cited by 38 publications

(74 citation statements)

References 22 publications

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“…The existence of a magnetic field threshold for reversal of a magnetic island in the presence of anisotropy has been studied experimentally in detail in Ref. 10; it was analyzed in a classical context 10 with a field threshold equal to 2K μ in the T = 0 K limit (μ is the magnetic moment per atom equal to gμ B S with the present notations). K is the anisotropy energy per atom, i.e., the energy barrier to reversal for a single atom, equal to equal to the quantum threshold given by Eq.…”

Section: A Effect Of the Longitudinal Anisotropy ( D = 0 E = 0)mentioning

confidence: 99%

“…At the time of the injection of the tunneling electron, a sharp change of the population of all the states in the manifold is visible, corresponding to the inelastic effect of the tunneling electrons [Eq. (10)]; most of these changes are sharp drops due to the excitation toward spin waves. For example, the sharp drop at t = 0.5 ns in the population of the M Tot = 5 state in the S Tot = 5 manifold (full green line) is due to excitation of higher-lying spin waves.…”

Section: Magnetization Switch Induced By Injected Electronsmentioning

confidence: 99%

“…The development of spin-polarized scanning tunneling microscopy (SP-STM) led to detailed observations of the thermally induced magnetic switch in small ferromagnets, allowing a detailed test of the global rotation of the Néel-Brown view and of its limits. [3][4][5][6][7][8][9][10] In parallel, analyses led to the discussion of other views of the thermally activated magnetization switch, [10][11][12][13][14][15][16][17] for example, spin-wave contributions, nucleation, edge effects, and anisotropy effect. Following earlier works on multilayered materials, 18,19 SP-STM experiments revealed that injection of spin-polarized electrons into a nanoferromagnet could also switch its magnetization.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic reversal of a quantum nanoferromagnet

Gauyacq

Lorente

2013

Phys. Rev. B

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When the external magnetic field applied to a ferromagnetically coupled atomic chain is reversed suddenly, the magnetization of the chain switches, due to the reversal of all the atomic magnetic moments in the chain. The quantum processes underlying the magnetization switching and the time required for the switching are analyzed for model magnetic chains adsorbed on a surface at 0 K. The sudden field reversal brings the chain into an excited state that relaxes towards the system ground state via interactions with the substrate electrons. Different mechanisms are outlined, ranging from the global stepwise rotation of the chain macrospin induced by spin-flip collisions with substrate electrons in the pure Heisenberg chain (Néel-Brown process) to a correlation-mediated direct switching process in the presence of strong magnetic anisotropies in short chains (the global spin of the chain reverses in a single electron interaction). The processes for magnetization switching induced by electrons tunneling from a scanning tunneling microscope tip are also analyzed.

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Section: A Effect Of the Longitudinal Anisotropy ( D = 0 E = 0)mentioning

confidence: 99%

Section: Magnetization Switch Induced By Injected Electronsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic reversal of a quantum nanoferromagnet

Gauyacq

Lorente

2013

Phys. Rev. B

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“…Figure 1(a) shows a schematic illustration of the preparation of a ferromagnetic tip on the surface of Fe 1+y Te: by collecting excess Fe (Fe-II) atoms from the surface of the material, which are attached to the apex of the STM tip, the tip is rendered magnetic. Experiments on cobalt islands on Cu(111) show that in order to obtain a magnetic cluster which is stable at temperatures below 10K on the order of 100 atoms will be required [10]. Fig.…”

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confidence: 99%

Preparation of magnetic tips for spin-polarized scanning tunneling microscopy onFe1+yTe

et al. 2015

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The interplay of electronic nematic modulations, magnetic order, superconductivity and structural distortions in strongly correlated electron materials calls for methods which allow characterizing them simultaneously -to allow establishing directly the relationship between these different phenomena. Spin-polarized STM enables studying both, electronic excitations as well as magnetic structure in the same measurement at the atomic scale. Here we demonstrate preparation of magnetic tips, both ferromagnetic and antiferromagnetic, on single crystals of FeTe. This opens up preparation of spin-polarized tips without the need for sophisticated ultra-high vacuum preparation.PACS numbers: 74.55.+v, 74.70.Xa In many unconventional superconductors, the superconducting phase is reached from a magnetically ordered state by some external tuning parameter, such as doping, pressure or chemical substitution. Superconductivity emerges in close vicinity to a magnetically ordered phase [1]. This suggests an intimate relation between magnetism and superconductivity in these materials. Often, the phase diagrams exhibit even regimes of coexistence between the two, however the important question about whether the two coexist or compete at the microscopic level remains unresolved. One difficulty in probing their relation at the atomic scale is that most methods employed to characterize magnetic order, such as neutron scattering, probe a macroscopic sample volume, rendering statements about local phase separation difficult. A method which has been very successful to characterize both superconductivity and magnetism locally on an atomic scale is Scanning Tunneling Microscopy (STM). It has provided important information both about local variations in the superconducting properties and charge ordering in strongly correlated electron materials [2][3][4] and, using magnetic tips in spin-polarized STM, it has also been shown to allow for characterization of magnetism at the atomic scale in nanostructures [5,6]. Application of spin-polarized STM to strongly correlated materials has recently been demonstrated in the nonsuperconducting parent compound of the iron chalcogenide superconductors [7], providing real space images of the magnetic structure Fe 1+δ Te. Preparing and calibrating a magnetic tip for spin-polarized STM measurements has been an important obstacle towards its application to strongly correlated electron materials.In this work, we demonstrate preparation of spinpolarized tips and the characterization of their magnetic properties on Fe 1+y Te. Presence of small amounts of excess iron proves instrumental in the preparation of spin-polarized tips on this material. Specifically we show preparation of both ferromagnetic and antiferromagnetic clusters at the apex of the tip and the characterization of the magnetization of the tip-cluster as a function of field.

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“…Cobalt bilayer islands on Au(111) are believed to reverse their magnetization by CR up to a size of 600 atoms, while a noncollinear magnon assisted process has been proposed for larger islands [7]. Finally, it was suggested that triangular Co bilayer islands on Cu(111) reverse by a single-element exchange spring mechanism for island sizes up to 7500 atoms, from where reversal takes place by DWs [11]. From these examples it is evident that the reversal kinetics of nanomagnets is complex and that the critical size for the reversal mechanism crossover of each transition metal element strongly depends on the substrate.…”

Section: Introductionmentioning

confidence: 99%

Magnetization reversal mechanism of ramified and compact Co islands on Pt(111)

et al. 2014

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We report on the magnetization reversal mechanism of Co islands on Pt(111) as a function of their size and shape. We measure the zero-field susceptibility χ (T ) and low-temperature magnetization curves M(H ) with in situ magneto-optical Kerr effect. Together with the island morphology deduced from scanning tunneling microscopy, this creates sufficient information to determine both the magnetization reversal mechanism and the distribution of anisotropy energies between perimeter and surface atoms. We find a transition from quasicoherent rotation to domain wall nucleation and propagation with a critical size of 350 atoms for ramified, and of 600 atoms for compact islands.

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Magnetization Reversal of Individual Co Nanoislands

Cited by 38 publications

References 22 publications

Magnetic reversal of a quantum nanoferromagnet

Magnetic reversal of a quantum nanoferromagnet

Preparation of magnetic tips for spin-polarized scanning tunneling microscopy onFe1+yTe

Magnetization reversal mechanism of ramified and compact Co islands on Pt(111)

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