Magnetic properties of thin Ni films measured by a dc SQUID-based magnetic microscope

Снигирев, О.В.; Andreev, K.E.; Tishin, A.M.; Гудошников, С.А.; Bohr, Jakob

doi:10.1103/physrevb.55.14429

Cited by 28 publications

(8 citation statements)

References 27 publications

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“…With increasing film thickness up to 150 nm and more, the easy direction is out-of-plane perpendicular to it. [81][82][83] Although in our experiment the film thicknesses satisfy this condition, below we calculate the upper bounds of the magnetic interaction for both out-of-plane and in-plane magnetizations and show that in both cases the gradient of magnetic force is negligibly small. Note that any other alignment of domains (which cannot occur in thin films but might be possible in thick magnetic bodies) can be presented as a superposition of these two.…”

Section: Calculation Of Magnetic Interaction In the Experimental Smentioning

confidence: 70%

Casimir interaction between two magnetic metals in comparison with nonmagnetic test bodies

et al. 2013

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We present the complete results for the dynamic experiment on measuring the gradient of the Casimir force between magnetic (Ni-coated) surfaces of a plate and a sphere. Special attention is paid to the description of some details of the setup, its calibration, error analysis and background effects. Computations are performed in the framework of the Lifshitz theory at nonzero temperature with account of analytic corrections to the proximity force approximation and of surface roughness using both the Drude and the plasma model approaches. The theory of magnetic interaction between a sphere and a plate due to domain structure of their surfaces is developed for both out-of-plane and in-plane magnetizations in the absence and in the presence of spontaneous magnetization. It is shown that in all cases the magnetic contribution to the measured force gradients is much smaller than the total experimental error. The comparison between experiment and theory is done using the rigorous statistical method. It is shown that the theoretical approach taking into account dissipation of free electrons is excluded by the data at a 95% confidence level.The approach neglecting dissipation is confirmed by the data at more than 90% confidence level.We prove that the results of experiments with Ni-Ni, Ni-Au and Au-Au surfaces taken together cannot be reconciled with the approach including free electrons dissipation by the introduction of any unaccounted background force, either attractive or repulsive.

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Section: Calculation Of Magnetic Interaction In the Experimental Smentioning

confidence: 70%

Casimir interaction between two magnetic metals in comparison with nonmagnetic test bodies

et al. 2013

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“…This is done by considering two parallel Ni films of L x ×L y = 0.9 ×1.1 cm 2 area and applying the general formulation of the proximity force approximation [3,51]. For films more than 150 nm thickness the magnetization of each domain is perpendicular to the film surfaces, i.e., has only the z-component equal to ±M s , where M s = 435 emu/cm 3 [52][53][54]. The magnetization of the first (1) and the second (2) films can be described by a function of two variables M (1,2) z (x, y).…”

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confidence: 99%

Demonstration of the Casimir Force between Ferromagnetic Surfaces of a Ni-Coated Sphere and a Ni-Coated Plate

et al. 2013

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We demonstrate the Casimir interaction between two ferromagnetic boundary surfaces using the dynamic atomic force microscope. The experimental data are found to be in excellent agreement with the predictions of the Lifshitz theory for magnetic boundary surfaces combined with the plasma model approach. It is shown that for magnetic materials the role of hypothetical patch potentials is opposite to that required for reconciliation of the data with the Drude model. PACS numbers: 78.20.Ls, 12.20.Fv, 78.67.Bf 1 The Casimir effect [1] is of much interest due to its promising multidisciplinary applications in nanotechnology, condensed matter physics, physics of elementary particles, and in gravitation and cosmology [2,3]. Many experiments on measuring the Casimir force between boundary surfaces made of different materials separated by a vacuum gap or a liquid have been performed in the last 15 years [4][5][6]. It was shown that the magnitude of the Casimir force can be controlled by using different boundary materials [7,8], phase transitions [9][10][11][12][13], and by using the boundary surfaces structured with nanoscale corrugations [14][15][16][17].An unified description of both the van der Waals and Casimir forces is given by the Lifshitz theory [18] in terms of the dielectric permittivity ε(ω) and magnetic permeability µ(ω). The role of magnetic materials in the Casimir force has been studied theoretically [19][20][21][22][23][24][25][26][27][28][29][30]. The interest stems from the possibility to obtain a repulsive Casimir force for application in micromachines. Using real magnetic materials [21,25] did not validate the early results which used constant ε and µ. As µ(iξ) can be large only at ξ < 10 5 − 10 9 Hz, its entire contribution to the Lifshitz formula is through the zero Matsubara frequency [27,28]. For metals, the zero-frequency term is strongly influenced by the inclusion (Drude model approach) or neglect (plasma model approach) of the relaxation properties of free electrons [4]. Thus using µ provides another parameter to study the role of the relaxation properties of free electrons in the Casimir effect. Some experiments demonstrate strong disagreement between the measured data and theoretical predictions when the relaxation properties of electrons are taken into account for metals [4,31,32] or the dc conductivity is included for dielectrics [4,12,13]. The same data are found to be consistent with theory when the relaxation properties are neglected for metals or the dc conductivity of dielectrics is disregarded. Two other experiments [33,34] are claimed to be in favor of the Drude model approach (see critical discussion in [35][36][37][38] Here we have used the same apparatus and cantilever preparation as in Refs. [32,40].The gradient of the Casimir force was measured acting between a Ni-coated hollow glass microsphere of R = 61.71 ± 0.09 µm radius attached to the tip of a rectangular Si cantilever and a Si plate also coated with Ni. The thicknesses of Ni coating were 210 ± 1 nm and 250 ± 1 n...

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“…However, an outstanding issue for these types of techniques is correctly assessing the importance of magnetic impurities. An extensive overview of the operational principles of most of the techniques is given in the review of Burch et al Two additional techniques to study magnetic interfaces using quantum beam science are low‐energy µSR and the related β‐nuclear magnetic resonance method . Both of these techniques monitor the polarization of highly spin‐polarized particles implanted near the surface, thereby offering sensitivity to small magnetic moments and fluctuating magnetic fields near surfaces .…”

Section: Third‐generation 2d Magnets: Vdw Magnetsmentioning

confidence: 99%

Two‐Dimensional Magnets: Forgotten History and Recent Progress towards Spintronic Applications

Cortie

Causer

Rule

et al. 2019

Adv Funct Materials

181

121

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The recent discovery of 2D magnetic order in van der Waals materials has stimulated a renaissance in the field of atomically thin magnets. This has led to promising demonstrations of spintronic functionality such as tunneling magnetoresistance. The frantic pace of this emerging research, however, has also led to some confusion surrounding the underlying phenomena of phase transitions in 2D magnets. In fact, there is a rich history of experimental precedents beginning in the 1960s with quasi-2D bulk magnets and progressing to the 1980s using atomically thin sheets of elemental metals. This review provides a holistic discussion of the current state of knowledge on the three distinct families of low-dimensional magnets: quasi-2D, ultrathin films, and van der Waals crystals. It highlights the unique opportunities presented by the latest implementation in van der Waals materials. By revisiting the fundamental insights from the field of low-dimensional magnetism, this review highlights factors that can be used to enhance material performance. For example, the limits imposed on the critical temperature by the Mermin-Wagner theorem can be escaped in three separate ways: magnetocrystalline anisotropy, long-range interactions, and shape anisotropy. Several recent experimental reports of atomically thin magnets with Curie temperatures above room temperature are highlighted.

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Magnetic properties of thin Ni films measured by a dc SQUID-based magnetic microscope

Cited by 28 publications

References 27 publications

Casimir interaction between two magnetic metals in comparison with nonmagnetic test bodies

Casimir interaction between two magnetic metals in comparison with nonmagnetic test bodies

Demonstration of the Casimir Force between Ferromagnetic Surfaces of a Ni-Coated Sphere and a Ni-Coated Plate

Two‐Dimensional Magnets: Forgotten History and Recent Progress towards Spintronic Applications

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