Thin Films Of Magnetic Materials Research Articles

Studies of novel magnetic systems by electron capture spectroscopy (ECS)

The electron spin polarization (ESP) at surfaces of bulk and artificially structured, thin film magnetic materials is studied using electron capture spectroscopy (ECS) and ion-induced emission of spin-polarized electron. For V and Tb surfaces, it is found that the temperature dependence of the surface magetic order is quite different from that of the bulk. For ultra-thin magnetic superlattices, V(100)/Ag(100) and Tb (0001)/W(110), we find novel magnetic surface anisotropies and critical behavior. At surfaces of 5 monolayers V(100) on Ag(100), the critical behavior of the surface-ESP is found to be identical to that of the two-dimensional Ising ferromagnet. At surfaces of PtMnSb and Fe80B20, we findnonzero ESP due to long-ranged or short-ranged ferromagnetic order. Thesign of the ESP at surfaces of the Heusler alloy PtMnSb is in agreement with recent band structure calculations. At surfaces of the spin glass Fe80B20, we find, in agreement with ECS data, that the ESP ofion-induced emitted spin-polarized electrons is extremely sensitive to the cleanness of thetopmost surface layer.

Magnetic susceptibility measurement method for thin films and surfaces

A new method is described for the measurement of the susceptibility of thin films of magnetic materials. This method uses the inductance change of a superconducting meander line as sensed by a tunnel diode oscillator and is specially suitable for measurements during deposition of the films on a cryogenically cooled substrate. The sensitivity of initial tests agree with design calculations and can detect 1% or less of the signal from a monolayer of Fe.

Non-magnetostrictive amorphous soft magnetic thin film material of high magnetization

Magnetically uniaxial amorphous Co79Fe6.5B14.5 films 1.5 μm in thickness were deposited by r.f. bias sputtering from a Co74Fe6B20 target onto glass and single crystal Si substrates. The saturation magnetostriction, λs, changed gradually from +0.6×10−6 to −0.4×10−6 when the d.c. bias voltage was increased from 0 to −120 V. In this bias voltage range 4πMs values from 11 up to 14 kG were measured. The influence of the Ar gas pressure on 4πMs and λs is weak. Coercivities of less than 0.05 Oe were obtained on Si substrates at bias voltages between −45 V and −90 V. The hard axis anisotropy field was decreased by hard axis field annealing at 240 °C from 12 Oe to below 3 Oe and the initial permeability increased up to 3600. The amorphous state was not affected by the annealing. The electrical resistivity of the material was 90 μΩ cm and the magneto-resistivity ratio Δρ/ρ was 0.2%. The high values of 4πMs and of the permeability, zero λs, and low Hc, combined with a high electrical resistivity suggest the application of the material in thin film magnetic devices operating at high frequencies. As for permalloy films also Co79Fe6.5B14.5 films must be protected from corrosive influences.