Evolution of the magnetic and electronic properties of ultrathin Cr(001) films (original) (raw)

Study of the growth and the magnetism of ultrathin films of Cr on Fe

Surface Science, 2000

The surface magnetic properties of ultrathin Cr films grown on an O/Fe/Ag(100) substrate have been studied by means of spin polarized metastable de-excitation spectroscopy. The presence of oxygen on top of the Fe film inhibits the segregation of Ag and strongly reduces Fe/Cr intermixing. The magnetization of the outermost Cr layer is zero immediately after its deposition, whereas, upon annealing up to 500 K, a net magnetization is observed which reverse its direction as a function of the film thickness already from a 3 ML thick film. The magnetization reversal is in agreement with the layered antiferromagnetic structure of Cr clearly observed for thicker films.

Noncollinear magnetism of thin Cr films deposited on a stepped Fe (001) surface

Physical Review B, 2003

A theoretical study of the noncollinear magnetic moments distribution of Cr films with thicknesses between one and two monolayers deposited on a semi-infinite Fe͑001͒ substrate with terraces of monoatomic height is reported. The spin-polarized electronic structure is calculated with a self-consistent real space spd tight-binding model, parametrized to ab initio tight binding linear muffin tin orbital results in which we have implemented the possibility that the orientation of the spin-quantization axis changes from site to site, thus allowing noncollinear magnetic calculations in complex systems with a large number of inequivalent sites without symmetry requirements while preserving a high degree of accuracy. The calculated magnetic moment distributions are discussed in connection with the magnetic frustrations associated with structural defects.

Direct observation of Cr spin polarization in epitaxial Cr/Co/Cr(100) trilayers

Physical Review B, 2013

The spin polarization of chromium at the interface next to a ferromagnetic layer is of general interest because of the competing ferromagnetic and antiferromagnetic exchange coupling. While the Fe/Cr interface has been well studied, information on the Co/Cr interface still remains scarce. Here we show for epitaxially grown Cr/Co/Cr(100) trilayers with smooth interfaces x-ray resonant magnetic scattering (XRMS) results in a saturation field of ±270 mT, recorded at the Co and Cr L 3 edges, respectively. The XRMS results at the Co edge show the expected asymmetry and a ferromagnetic hysteresis for different incident angles θ. Furthermore, XRMS measurements with the energy tuned to the Cr L 3 edge also exhibit an asymmetry, albeit much smaller than the one at the Co L 3 edge. Moreover, the magnetic hysteresis of Cr taken at the L 3 edge has a sign opposite to that of Co at the L 3 edge over a broad range of incident angles. From these results we infer first that at the Co/Cr interface chromium is ferromagnetically polarized, and second that its spin structure is oriented opposite to the magnetization of Co.

Photoemission study of the spin-density-wave state in thin films of Cr

Physical Review B, 2004

Angle-resolved photoemission (PE) was used to characterize the spin-density wave (SDW) state in thin films of Cr grown on W(110). The PE data were analysed using results of local spin density approximation layer-Korringa-Kohn-Rostoker calculations. It is shown that the incommensurate SDW can be monitored and important parameters of SDW-related interactions, such as coupling strength and energy of collective magnetic excitations, can be determined from the dispersion of the renormalized electronic bands close to the Fermi energy. The developed approach can readily be applied to other SDW systems including magnetic multilayer structures.

Magnetic dichroism and spin-resolved photoemission from rough interfaces

Physical Review B, 1999

The magnetic structure of ultrathin Cr films on Fe is analyzed by taking into account the roughness of the surface and of the interface. An algorithm for the epitaxial growth of the film simulates the near-surface structure, and the magnetic moment distribution is calculated self-consistently in a periodic Anderson model. For rough interfaces we find that the layered antiferromagnetic structure of the Cr adlayer is quenched. Within this model we determine the spin polarization and the value of the magnetic linear dichroism to be expected in angle-resolved photoemission. Comparing with experimental data it is concluded that Cr grows on the Fe͑001͒ in a Stranski-Kastranoff mode. We propose an explanation based on the confinement of the itinerant electrons within the Cr islands on the Fe substrate. ͓S0163-1829͑99͒13801-3͔

Fe/Cr multilayers: Effect of annealing on the spin structure and magnetoresistance

Journal of Applied Physics, 1994

Optimization of Co/Pt multilayers for applications of current-driven domain wall propagation J. Appl. Phys. 110, 083913 (2011) Magnetic properties of sputtered Permalloy/molybdenum multilayers J. Appl. Phys. 110, 083910 (2011) Electric control of magnetization relaxation in thin film magnetic insulators Appl. Phys. Lett. 99, 162511 (2011) CoFe2O4/buffer layer ultrathin heterostructures on Si(001) J. Appl. Phys. 110, 086102 Large amplitude microwave emission and reduced nonlinear phase noise in Co2Fe(Ge0.5Ga0.5) Heusler alloy based pseudo spin valve nanopillars Appl. Phys. Lett. 99, 162508 (2011) Additional information on J. Appl. Phys.

Interdiffusion and exchange coupling in Cr overlayers on a Fe(001) substrate

Physical Review B, 2000

The influence of interfacial interdiffusion on the magnetic order in ultrathin epitaxial Cr films on a Fe͑001͒ substrate was studied by means of electronic structure calculations. The total coverage of the films was assumed to be one, two, and six monolayers of Cr while the interdiffusion was simulated by two-dimensional Cr-Fe alloys in the two atomic layers forming the Cr/Fe interface. Two limiting cases were considered: ͑i͒ perfectly ordered alloys, described in terms of a semiempirical tight-binding method using the recursion technique, and ͑ii͒ substitutionally disordered alloys, whose electronic structure was determined ab initio using the tight-binding linear muffin-tin orbital method and the coherent-potential approximation. In both cases, the magnetic coupling of the Cr overlayer to the ferromagnetic Fe substrate exhibits similar transitions (phase shifts͒ due to varying compositions at the interface. The calculated results provide additional support for recent interpretations of experiments on Fe/Cr/Fe͑001͒ trilayers.

Spiral Terraces and Spin Frustration in Layered Antiferromagnetic Cr (001) Films

Physical Review Letters, 2005

We have successfully fabricated a novel type of high-density spiral terraces on Cr(001) films. The influence of nanoscale spiral terraces on layered antiferromagnetic ordering of Cr(001) films has been studied at room temperature by direct imaging of both topographic and magnetic structures using spinpolarized scanning tunneling spectroscopy. Spin frustration and asymmetric magnetic ordering due to dense spiral terraces are observed. Sizable modification of the layered antiferromagnetic order is found to be originating from the topological asymmetry as confirmed by the continuum micromagnetic simulation.