The spin polarization of Pt in Pt/NiFe2O4 and Pt/Fe bilayers is studied by interface-sensitive x-ray resonant magnetic reflectivity to investigate static magnetic proximity effects. The asymmetry ratio of the reflectivity was measured at the Pt L3 absorption edge using circular polarized x-rays for opposite directions of the magnetization at room temperature. The results of the 2% asymmetry ratio for Pt/Fe bilayers are independent of the Pt thickness between 1.8 and 20 nm. By comparison with ab initio calculations, the maximum magnetic moment per spin polarized Pt atom at the interface is determined to be (0.6 ± 0.1) µB for Pt/Fe. For Pt/NiFe2O4 the asymmetry ratio drops below the sensitivity limit of 0.02 µB per Pt atom. Therefore, we conclude, that the longitudinal spin Seebeck effect recently observed in Pt/NiFe2O4 is not influenced by a proximity induced anomalous Nernst effect. In spintronics1 and spin caloritronics 2 pure spin currents can be generated in ferromagnetic insulators (FMIs) by spin pumping 3 , the spin Hall effect 4 and the spin Seebeck effect 5 . Since these spin currents play an important role in spintronic applications, an understanding of the generation, manipulation and detection of spin currents is an important topic of research. A common spin current detection technique uses a nonferromagnetic metal (NM) thin film grown on a ferromagnet (FM). The inverse spin Hall effect 6 converts the spin current into a transverse voltage in the NM. Pt is commonly used as NM due to its large spin Hall angle 7 , but has generated some controversy in the interpretation because of its closeness to the Stoner criterion, which can induce, e.g., Hall or Nernst effects due to the proximity to the FM 8 .For a quantitative evaluation of the spin Seebeck effect (thermal generation of spin currents) one has to exclude or separate various parasitic effects. It is reported 5 that in transverse spin Seebeck experiments a spin current is generated perpendicular to the applied temperature gradient which is typically aligned in-plane. For ferromagnetic metals (FMMs) with magnetic anisotropy, the planar Nernst effect 9 can contribute 10 due to the anisotropic magnetothermopower. Furthermore, out-of-plane temperature gradients due to heat flow into the surrounding area 11 or through the electrical contacts 12 can induce an anomalous Nernst effect (ANE) [13][14][15] or even an unintended longitudinal spin Seebeck effect as recently reported 16 .The longitudinal spin Seebeck effect (LSSE) 17 describes a spin current that is generated parallel to the temperature gradient, which is typically aligned outof-plane to drive the parallel spin current directly into the NM material. For FMMs or semiconducting ferromagnets an ANE can also contribute to the measured voltage 18 . Furthermore, for NM materials close to the Stoner criterion a static magnetic proximity effect in the NM at the NM/FMI interface can lead to a proximity induced ANE 8 . If an in-plane temperature gradient is applied, a proximity induced planar Nernst effect ...

A survey of the possible autocatalytic crystallization processes called explosive crystallization in liquid and solid states is given. The explosive liquid-phase epitaxy with laterally moving coupled interfaces of melting and crystallization in amorphous silicon layers on insulators is investigated by the use of an experimental equipment consisting of three synchronized lasers supplying the temperature pulses for ignition, spreading, and stopping of the explosive front. The velocity of this explosive crystallization front measured by use of time-resolved reflectivity of a test beam is compared with the results of model calculations. The results are in good agreement. The crystal structure was investigated by optical and transmission electron micrography and represents crystalline laminae grown preferentially in the 〈110〉 direction over a distance of about 100 μm. Areas of some millimeters in diameter can be crystallized by this method.

The magnetic and magneto-optic properties of epitaxial CeY 2 Fe 5 O 12 (Ce∶YIG) and Y 3 Fe 5 O 12 (yttrium iron garnet or YIG) thin films grown by pulsed laser deposition on gadolinium gallium garnet substrates are determined. An enhanced Faraday effect is known to result from Ce substitution into the yttrium iron garnet lattice, and here we characterize the magneto-optic Kerr effect, as well as the magnetic hysteresis and ferromagnetic resonance response that result from the Ce substitution. X-ray diffraction analysis reveals a high crystallographic quality for the Ce∶YIG films. Measurements of the magneto-optic Kerr effect for two different wavelengths demonstrate that the Ce∶YIG exhibits an up-to-tenfold increase in Kerr rotation compared to YIG. The Ce∶YIG has a slightly larger magnetic moment, as well as increased magnetic damping and higher magnetic anisotropy compared to YIG with a dependence on the crystalline orientation. By specific cerium substitution in YIG, our results show that the engineering of a large Kerr effect and tailored magnetic anisotropy becomes possible as required for magneto-optically active spintronic devices.

No abstract

No abstract