The x-ray magnetic circular dichroism (XMCD) sum rule yields an extremely useful ground-state observable, which provides a quantitative measure of spontaneous time-reversal symmetry breaking (T-breaking) in a given material. I derive here its explicit expression within band-structure theory, in the general case: trivial insulators, topological insulators, and metals. Orbital magnetization provides a different measure of T-breaking in the electronic ground state. The two observables belong to the class of "geometrical" observables; both are local and admit a "density" in coordinate space. In both of them one could include/exclude selected groups of bands, in order to acquire element-specific information about the T-breaking material. Only in the case of an isolated flat band the contributions to the two observables coincide. Finally, I provide the corresponding geometrical formula-in a different Hilbert space-for a many-body interacting system.
Magnetic circular dichroism (MCD) of rutile Ti1-xCoxO2-d is systematically examined with various x and d to reveal a phase diagram for the appearance of ferromagnetism at higher carrier concentration and Co content. The phase diagram exactly matches with that determined from anomalous Hall effect (AHE). The magnetic field dependence of MCD also shows good coincidence with those of the magnetization and AHE. The coincidence of these independent measurements strongly suggests single and intrinsic ferromagnetic origin.
We present a unified interpretation of experimentally observed magnetic circular dichroism (MCD) in the ferromagnetic semiconductor (Ga,Mn)As, based on theoretical arguments, which demonstrates that MCD in this material arises primarily from a difference in the density of spin-up and spin-down states in the valence band brought about by the presence of the Mn impurity band, rather than being primarily due to the Zeeman splitting of electronic states.
We have studied magnetism in Ti_[1-x]Co_xO_[2-δ] thin films with various x and δby soft x-ray magnetic circular dichroism (XMCD) measurements at the Co L_[2,3] absorption edges. The estimated ferromagnetic moment by XMCD was 0.15-0.24 μβ/Co in the surface, while in the bulk it was 0.82-2.25 μβ/Co, which is in the same range as the saturation magnetization of 1.0-1.5 μβ/Co. Theseresults suggest that the intrinsic origin of the erromagnetism. The smaller moment of Co atom at surface is an indication of a magnetically dead layer of a few nm thick at the surface of the thin films.
The question of the correlation between magnetization, band splittings, and magnetic circular dichroism (MCD) in the fundamental gap region of dilute magnetic semiconductors is examined experimentally and theoretically taking the case of wurtzite Ga(1-x)FexN as an example. Magnetization and polarization-resolved reflectivity measurements have been performed down to 2K and up to 7T for x = 0.2%. Optical transitions originating from all three free excitons A, B and C, specific to the wurtzite structure, have been observed and their evolution with the magnetic field determined. It is demonstrated…
X-ray magnetic circular dichroism at the Er M4,5 edge is used to study the switching behavior of the hard ErFe2 layers in an epitaxial [ErFe2(70Å)/YFe2 (150Å)]{\times}25 exchange-spring superlattice. Magnetic hysteresis loops for the Er magnetization, at temperatures T < 200 K, reveal a switching behavior with a single type of irreversible switch corresponding to vertical exchange spring states. Experiments at T > 200 K reveal a crossover to a regime with two types of switching processes. Computational modelling for this system gives a semi-quantitative agreement with the experiment and reveal…
X-ray photoelectron emission microscopy in combination with x-ray magnetic circular dichroism is used to investigate the influence of an applied magnetic field on Néel caps (i.e., surface terminations of asymmetric Bloch walls). Self-assembled micron-sized Fe(110) dots displaying a moderate distribution of size and aspect ratios serve as model objects. Investigations of remanent states after application of an applied field along the direction of Néel-cap magnetization give clear evidence for the magnetization reversal of the Néel caps around 120 mT, with a $\pm$20 mT dispersion. No clear corre…
Co islands and films are characterized by x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM). The spatial resolution capabilties of the technique together with atomic growth control permit obtaining perfectly flat triangular islands with a given thickness (3 ML), very close to an abrupt spin-reorientation transition. The magnetic domain configurations are found to depend on island size: while small islands can be magnetized in a single-domain state, larger islands show more complex patterns. Furthermore, the magnetization pattern of the larger islands presents a co…
In this work, we study the time- and temperature-dependence of optically induced magnetization in bulk crystals of slightly oxygen-deficient SrTiO$_{3-δ}$ using an optically coupled SQUID magnetometer. We find that a weak ($\sim$5$\times$10$^{-7}$~emu) but extremely long-lived (hours) magnetic moment can be induced in SrTiO$_{3-δ}$ at zero magnetic field by circular-polarized sub-bandgap light. We utilize this effect to demonstrate that SrTiO$_{3-δ}$ crystals can be used as an optically addressable magnetic memory by writing and subsequently reading magnetic patterns with light. The induced ma…
Investigation of magnetic materials using the first-order magneto-optical Kerr effects (MOKE) is well established and is frequently used in the literature. On the other hand, the utilization of the second-order (or quadratic) magneto-optical (MO) effects for the material research is rather rare. This is due to the small magnitude of quadratic MO signals and the fact that the signals are even in magnetization (i.e., they do not change a sign when the magnetization orientation is flipped), which makes it difficult to separate second-order MO signals from various experimental artifacts. In 2005 a…
In order to investigate the mechanism of ferromagnetic ordering in the new n-type magnetic semiconductor (In,Fe)As co-doped with Be, we have performed X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) studies of ferromagnetic and paramagnetic samples. The spectral line shapes suggest that the ferromagnetism is intrinsic originating from Fe atoms incorporated into the Zinc-blende-type InAs lattice. The magnetization curves of Fe measured by XMCD were well reproduced by the superposition of a Langevin function representing superparamagnetic (SPM) behavior of nano-scale f…
X-ray magnetic circular dichroism (XMCD) signals are usually absent in antiferromagnets. In this letter, we report the observation of spontaneous XMCD spectra originating from the inverse triangular spin structure, or the polarization of the cluster magnetic octupole, in the chiral antiferromagnet Mn$_{3}$Sn thin film. The result is consistent with the recent theoretical predictions that the inverse triangular spin structure can give rise to finite XMCD signals in the absence of net magnetization [J. Phys. Soc. Jpn. 89, 083703 (2020) and Phys. Rev. Lett. 126, 157402 (2021)].
X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L$_{3,2}$-edges. This new ultrafast time-resolved capability is then applied to a fluence-dependent study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature. At the magnetic switching fuence, we corroborate the existence of a transient ferromagnetic-like state. The timescales of the dynamics, however, are longer than previously observed below the magnetization compensation temp…
Tetragonally distorted \(\rm{Mn}_{3-x}\rm{Ga}_x\) thin films with \(0.1< x < 2\) show a strong perpendicular magnetic anisotropy and low magnetization and thus have the potential to serve as electrodes in spin transfer torque magnetic random access memory. Because a direct capping of these films with MgO is problematic due to oxide formation, we examined the influence of a CoFeB interlayer, and of two different deposition methods for the MgO barrier on the formation of interfacial MnO for \(\rm{Mn}_{62}\rm{Ga}_{38}\) by element specific X-ray absorption spectroscopy (XAS) and magnetic circular…
We performed a soft x-ray magnetic circular dichroism (XMCD) study of a Zn$_{1-x}$V$_x$O thin film which showed small ferromagnetic moment. Field and temperature dependences of V 2$p$ XMCD signals indicated the coexistence of Curie-Weiss paramagnetic, antiferromagnetic, and possibly ferromagnetic V ions, quantitatively consistent with the magnetization measurements. We attribute the paramagnetic signal to V ions substituting Zn sites which are somewhat elongated along the c-axis.
We use temperature-dependent Hall measurements to identify contributions of spin Hall, magnetic proximity, and sublattice effects to the anomalous Hall signal in heavy metal/ferrimagnetic insulator heterostructures with perpendicular magnetic anisotropy. This approach enables detection of both the magnetic proximity effect onset temperature and the magnetization compensation temperature and provides essential information regarding the interfacial exchange coupling. Onset of a magnetic proximity effect yields a local extremum in the temperature-dependent anomalous Hall signal, which occurs at h…
Using element-specific X-ray magnetic circular dichroism (XMCD) technique we have studied different magnetic sublattices in a multiferroic Ho$_{0.5}$Nd$_{0.5}$Fe$_{3}$(BO$_{3}$)$_{4}$ single crystal. The XMCD measurements at the \emph{L}$_{2,3}$-edges of Ho and Nd, and at the Fe \emph{K}-edge have been performed at \emph{T}=2~K under a magnetic field up to 17~T applied along the trigonal \emph{c}-axis as well as in the basal \emph{ab}-plane. All three magnetic sublattices are shown to undergo a spin-reorientation transition under magnetic field applied along the \emph{c}-axis. On the contrary,…
Epitaxial thin films of the half-metallic Xa-compound Mn2CoGa (Hg2CuTi prototype) were prepared by dc magnetron co-sputtering with different heat treatments on MgO (001) substrates. High-quality films with a bulk magnetization of 1.95(5)μ_B per unit cell were obtained. The L3,2 x-ray magnetic circular dichroism spectra agree with calculations based on density functional theory (DFT) and reveal the antiparallel alignment of the two inequivalent Mn moments. X-ray magnetic linear dichroism, in good agreement with theory as well, allows to distinguish between itinerant and local Mn moments. Based …
The spin and orbital magnetic moments of the Fe3O4 epitaxial ultrathin film synthesized by plasma assisted simultaneous oxidization on MgO(100) have been studied with X-ray magnetic circular dichroism (XMCD). The ultrathin film retains a rather large total magnetic moment, i.e. (2.7+-0.15) uB/f.u., which is ~ 70% of that for the bulk-like Fe3O4. A significant unquenched orbital moment up to (0.54+-0.05) uB/f.u. was observed, which could come from the symmetry breaking at the Fe3O4/MgO interface. Such sizable orbital moment will add capacities to the Fe3O4-based spintronics devices in the magne…
We demonstrate sensitivity of the Mn 3d valence states to strain in the ferromagnetic semiconductors (Ga,Mn)As and (Al,Ga,Mn)As, using x-ray magnetic circular dichroism (XMCD). The spectral shape of the Mn $L_{2,3}$ XMCD is dependent on the orientation of the magnetization, and features with cubic and uniaxial dependence are distinguished. Reversing the strain reverses the sign of the uniaxial anisotropy of the Mn $L_3$ pre-peak which is ascribed to transitions from the Mn 2p core level to p-d hybridized valence band hole states. With increasing carrier localization, the $L_3$ pre-peak intensi…
A detailed theoretical study on the electronic structure and magnetic properties of half-metallic ferromagnet CrO$_2$ was carried out by means of relativistic full-potential linear muffin-tin orbital method within the generalized gradient approximation (GGA) to the exchange correlation potential. Our calculation favours the [001] magnetization axis to be the easy axis of magnetization when compared to the [100] axis which is in agreement with the experiments. The calculated spin and orbital magnetic moments of Cr agrees well with the experimental and other theoretical works. The Cr L$_{2,3}$ x…
We have performed a theoretical study of the magnetic circular dichroism in the x-ray absorption spectra (XMCD) of the equiatomic CoPt and FePt ordered alloys as a function of the spin quantization axis. We found that the magnetization axis is along the [001] direction and the magneto-crystalline anisotropy energy (MCA) for the FePt compound is twice as large as that of the CoPt compound in agreement with experiment. The band structure and the total density of states confirm that all electronic states contribute to the MCA, and not just the states at the vicinity of the Fermi level. The orbita…
Shadow X-ray Magnetic Circular Dichroism Photo-Emission Electron Microscopy (XMCD-PEEM) is a recent technique, in which the photon intensity in the shadow of an object lying on a surface, may be used to gather information about the three-dimensional magnetization texture inside the object. Our purpose here is to lay the basis of a quantitative analysis of this technique. We first discuss the principle and implementation of a method to simulate the contrast expected from an arbitrary micromagnetic state. Text book examples and successful comparison with experiments are then given. Instrumental …
The magnetic atom diffusion at the interface between CoMn alloy and MnGa layer with annealing is studied using x-ray magnetic circular dichroism (XMCD) analysis. We found that the spins in bcc CoMn are coupled parallel to those in perpendicularly magnetized MnGa layer under the as-grown conditions, while the post-annealing modulates the interfacial magnetic coupling to antiferromagnetic in Co. The element-specific hysteresis curves at each absorption edge revealed the large coercive fields in Mn and Co through the exchange coupling with MnGa. After the annealing process, the changes of XMCD sp…
Magnetic linear dichroism and birefringence in (Ga,Mn)As epitaxial layers is investigated by measuring the polarization plane rotation of reflected linearly polarized light when magnetization lies in the plane of the sample. We report on the spectral dependence of the rotation and ellipticity angles in a broad energy range of 0.12-2.7 eV for a series of optimized samples covering a wide range on Mn-dopings and Curie temperatures and find a clear blue shift of the dominant peak at energy exceeding the host material band gap. These results are discussed in the general context of the GaAs host ba…
We study the electronic structure and the magnetic properties of epitaxial (Ni1-xCox)Fe2O4(111) layers (x = 0 - 1) with thicknesses d = 1.7 - 5.2 nm grown on Al2O3(111)/Si(111) structures, to achieve a high value of inversion parameter y, which is the inverse-to-normal spinel-structure ratio, and hence to obtain good magnetic properties even when the thickness is thin enough for electron tunneling as a spin filter. We revealed the crystallographic (octahedral Oh or tetrahedral Td) sites and the valences of the Fe, Co, and Ni cations using experimental soft X-ray absorption spectroscopy and X-r…
In the perovskite-type Ca$_{1-x}$Ce$_{x}$MnO$_{3}$ (CCMO), one can control the transport and magnetic properties through varying Ce content. In the case of thin films, the properties can also be controlled by epitaxial strain from the substrate through changing it such as YAlO$_{3}$ (YAO), NdAlO$_{3}$ (NAO), and LaSrAlO$_{4}$ (LSAO). However, one cannot measure the magnetization of thin films on NAO substrates by conventional magnetization measurements because of the strong paramagnetic signals from the Nd$^{3+}$ ions. In order to eliminate the influence of Nd$^{3+}$ and to identify magnetic p…
Epitaxial CoFe2O4/Al2O3 bilayers are expected to be highly efficient spin injectors into Si owing to the spin filter effect of CoFe2O4. To exploit the full potential of this system, understanding the microscopic origin of magnetically dead layers at the CoFe2O4/Al2O3 interface is necessary. In this paper, we study the crystallographic and electronic structures and the magnetic properties of CoFe2O4(111) layers with various thicknesses (thickness d = 1.4, 2.3, 4, and 11 nm) in the epitaxial CoFe2O4(111)/Al2O3(111)/Si(111) structures using soft X-ray absorption spectroscopy (XAS) and X-ray magne…
We have performed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) studies of the diluted ferromagnetic semiconductor Zn$_{1-\textit{x}}$Cr$_\textit{x}$Te doped with iodine (I) or nitrogen (N), corresponding to electron or hole doping, respectively. From the shape of the Cr $2p$ absorption peak in the XAS spectra, it was concluded that Cr ions in the undoped, I-doped and lightly N-doped samples are divalent (Cr$^{2+}$), while Cr$^{2+}$ and trivalent (Cr$^{3+}$) coexist in the heavily N-doped sample. This result indicates that the doped nitrogen atoms act as acce…
In this study, X-ray absorption spectroscopy (XAS) experiments for Ni45Co5Mn36.7In13.3 metamagnetic shape memory alloy were performed under high magnetic fields up to 12 T using a pulsed magnet. Field-induced reverse transformation to austenite phase caused considerable changes in the magnetic circular dichroism (MCD) signals and the magnetic moments of the ferromagnetic coupling between Mn, Ni, and Co were determined. The spin magnetic moment, Mspin, and orbital magnetic moment, Morb, of Mn atom in the induced austenite ferromagnetic phase, estimated based on the magneto-optical sum rule, wer…
Linear dichroism -- the polarization dependent absorption of electromagnetic waves -- is routinely exploited in applications as diverse as structure determination of DNA or polarization filters in optical technologies. Here filamentary absorbers with a large length-to-width ratio are a prerequisite. For magnetization dynamics in the few GHz frequency regime strictly linear dichroism was not observed for more than eight decades. Here, we show that the bulk chiral magnet Cu$_{2}$OSeO$_{3}$ exhibits linearly polarized magnetization dynamics at an unexpectedly small frequency of about 2 GHz. Unlik…
Time-resolved x-ray magnetic circular dichroism (XMCD) enables a unique spectroscopic view on complex spin and charge dynamics in multi-elemental magnetic materials. So far, its application in the soft-x-ray range has been limited to synchrotron-radiation sources and free-electron lasers. By combining a laser-driven plasma source with a magnetic thin-film polarizer, we generate circularly polarized photons in the soft x-ray regime, enabling the first XMCD spectroscopy at the Fe L edges in a laser laboratory. Our approach can be readily adapted to other transition metal L and rare earth M absor…
Magnetic anisotropy of epitaxially grown thin films is affected by the strain from the substrates due to a combined effect of distorted electronic structure and spin-orbit interaction (SOI). As an inverse process, one expects an anisotropy of the electronic structure induced by magnetization in the presence of SOI. We have studied the charge-density anisotropy induced by magnetization in thin films of the ferromagnetic metal La$_{1-x}$Sr$_{x}$MnO$_3$ via x-ray magnetic linear dichroism (XMLD). XMLD measurements on thin films with various thicknesses have shown that the XMLD intensity is propor…
The relationship between the modern and classical Landau's approach to carrier orbital magnetization is studied theoretically within the envelope function approximation, taking ferromagnetic (Ga,Mn)As as an example. It is shown that while the evaluation of hole magnetization within the modern theory does not require information on the band structure in a magnetic field, the number of basis wave functions must be much larger than in the Landau approach to achieve the same quantitative accuracy. A numerically efficient method is proposed, which takes advantages of these two theoretical schemes. …
In this article we review and discuss a mechanism for coupling between electric polarization and magnetization that can ultimately lead to electric-field switchable magnetization. The basic idea is that a ferroelectric distortion in an antiferromagnetic material can "switch on" the Dzyaloshinskii-Moriya interaction which leads to a canting of the antiferromagnetic sublattice magnetizations, and thus to a net magnetization. This magnetization M is coupled to the polarization P via a trilinear free energy contribution of the form P(M x L), where L is the antiferromagnetic order parameter. In par…
We have investigated the spin and orbital magnetic moments of Fe in FePt nanoparticles in the $L$1$_{0}$-ordered phase coated with SiO$_{2}$ by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at the Fe $L_{\rm 2,3}$ absorption edges. Using XMCD sum rules, we evaluated the ratio of the orbital magnetic moment ($M_{\rm orb}$) to the spin magnetic moment ($M_{\rm spin}$) of Fe to be $M_{\rm orb}/M_{\rm spin}$ = 0.08. This $M_{\rm orb}/M_{\rm spin}$ value is comparable to the value (0.09) obtained for FePt nanoparticles prepared by gas phase condensati…
BiFeO$_3$ (BFO) shows both ferroelectricity and magnetic ordering at room temperature but its ferromagnetic component, which is due to spin canting, is negligible. Substitution of transition-metal atoms such as Co for Fe is known to enhance the ferromagnetic component in BFO. In order to reveal the origin of such magnetization enhancement, we performed soft x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD) studies of BiFe$_{1-x}$Co$_x$O$_3$ ({\it x} = 0 to 0.30) (BFCO) thin films grown on LaAlO$_3$(001) substrates. The XAS results indicated that the Fe and C…
Ferrimagnetic alloys are extensively studied for their unique magnetic properties leading to possible applications in perpendicular magnetic recording, due to their deterministic ultrafast switching and heat assisted magnetic recording capabilities. On a prototype ferrimagnetic alloy we demonstrate fascinating properties that occur close to a critical temperature where the magnetization is vanishing, just as in an antiferromagnet. From the X-ray magnetic circular dichroism measurements, an anomalous 'wing shape' hysteresis loop is observed slightly above the compensation temperature. This bear…
We present experimental XMLD spectra measured on epitaxial (001)-oriented thin Co$_{2}$FeSi films, which are rich in features and depend sensitively on the degree of atomic order and interdiffusion from capping layers. Al- and Cr-capped films with different degrees of atomic order were prepared by DC magnetron sputtering by varying the deposition temperatures. The local structural properties of the film samples were additionally investigated by nuclear magnetic resonance (NMR) measurements. The XMLD spectra of the different samples show clear and uniform trends at the $L_{3,2}$ edges. The Al-c…
In this paper we present an analysis of the magnetic toroidal moment and its relation to the various structural modes in R3c-distorted perovskites with magnetic cations on either the perovskite A or B site. We evaluate the toroidal moment in the limit of localized magnetic moments and show that the full magnetic symmetry can be taken into account by considering small induced magnetic moments on the oxygen sites. Our results give a transparent picture of the possible coupling between magnetization, electric polarization, and toroidal moment, thereby highlighting the different roles played by th…
We argue that the magnetic circular dichroism (MCD) of the hard x-ray Raman scattering (XRS) could be used as an element selective probe of local spin polarization. The magnitude of the XRS-MCD signal is directly proportional to the local spin polarization when the angle between the incident wavevector and the magnetization vector is $135^{\circ}$ or $-45^{\circ}$. By comparing the experimental observation and the configuration interaction calculation at the $L_{2,3}$ and $M_{2,3}$ edges of ferromagnetic iron, we suggest that the integrated MCD signal in terms of the transferred energy could b…
Noncollinear chiral spin textures in ferromagnetic multilayers are at the forefront of recent research in nano-magnetism with the promise for fast and energy-efficient devices. The recently demonstrated possibilities to stabilize such chiral structures in synthetic antiferromagnets (SAF) has raised interests as they are immune to dipolar field, hence favoring the stabilization of ultra small textures, improve mobility and avoid the transverse deflections of moving skyrmions limiting the efficiency in some foreseen applications. However, such systems with zero net magnetization are hence diffic…
X-ray magnetic circular dichroism (XMCD) at the Eu L-edge (2p->5d) in two compounds exhibiting valence fluctuation, namely EuNi2(Si0.18Ge0.82)2 and EuNi2P2, has been investigated at pulsed high magnetic fields of up to 40 T. A distinct XMCD peak corresponding to the trivalent state (Eu3+; f6), whose ground state is nonmagnetic (J=0), was observed in addition to the main XMCD peak corresponding to the magnetic (J=7/2) divalent state (Eu2+; f7). This result indicates that the 5d electrons belonging to both valence states are magnetically polarized. It was also found that the ratio P5d(3+)/P5d(2+…
Many magnetic equilibrium states and phase transitions are characterized by fluctuations. Such magnetic fluctuation can in principle be detected with scattering-based x-ray photon correlation spectroscopy (XPCS). However, in the established approach of XPCS, the magnetic scattering signal is quadratic in the magnetic scattering cross section, which results not only in often prohibitively small signals but also in a fundamental inability to detect negative correlations (anticorrelations). Here, we propose to exploit the possibility of heterodyne mixing of the magnetic signal with static charge …
Pumping graphene with circularly polarized light is the archetype of light-tailoring topological bands. Realizing the induced Floquet-Chern insulator state and tracing clear experimental manifestions has been a challenge, and it has become clear that scattering effects play a crucial role. We tackle this gap between theory and experiment by employing microscopic quantum kinetic calculations including realistic electron-electron and electron-phonon scattering. Our theory provides a direct link to the build-up of the Floquet-Chern insulator state in light-driven graphene and its detection in tim…
Giant and Broadband Circular Dichroism from Particle-Hole Symmetry Breaking in Weyl Semimetals
East China Normal University（华东师范大学）；Fudan University（复旦大学）；Sun Yat-sen University（中山大学）；Southern University of Science and Technology (SUSTech)（南方科技大学）
A theoretical study is made of the magnetization versus applied field curves of ferromagnetic/nonmagnetic multilayers constructed according to a Fibonacci quasiperiodic sequence. The ferromagnetic films are assumed to have uniaxial anisotropy and are coupled by both bilinear and biquadratic effective exchange. The effects of quasiperiodicity in the magnetic phases are illustrated numerically for Fe/Cr systems.
The knowledge of how the magnetization looks inside a ferromagnet is often hindered by the limitations of the available experimental methods that are sensitive only to the surface regions or limited in spatial resolution. We report the 3D tomographic reconstruction of the magnetization within a ferromagnetic film of 240 nm in thickness using soft X ray microscopy and magnetic dichroism. The film has periodic magnetic domains forming stripes and closure domains found to be shifted from the stripe array by 1/4 of the period. In addition, the bifurcations of the stripes, which act as inversion nu…
Parametric plots of the remagnetization versus demagnetization remnances were found for four metallic ferromagnets -- nickel wire, two types of AlNiCo, and samarium cobalt 2:17. These plots, known as Henkel plots, were compared to Wohlfarth's model for noninteracting magnetic particles and several Preisach models. The remagnetization data were taken with a variety of paths to the net zero magnetization state. The resulting Henkel plots exhibit similarities to independent Monte Carlo simulations. The differences can be mostly explained by considering that the magnetization in the metallic ferro…
