Physico-chemical characterization of multilayer YIG thin film deposited by rf sputtering

Abstract

Yttrium iron garnet (YIG) film made as a magneto-optical medium suffers from the problem of crack formation, caused by the heating process. YIG thin film is deposited by radio frequency RF magnetron sputtering; the obtained layer is amorphous and it needs annealing to be crystallized. After heat-treatment at 740 o C of the sample realized on quartz substrate, we observe cracks on the entire film surface. This is due to the large difference between the thermal expansion coefficient (5.5 x 10 -7 K -1 for quartz and 10 x 10 -6 K -1 for YIG). In this paper we present a new fabrication method to reduce this problem, we make a multilayer to obtain at the end a uniformly unique layer with excellent crystalline structure. Such films have the possibility to reach a thickness of 500 nm. YIG films have been studied by Rutherford Backscattering Spectrometry (RBS), opticEllipsometry and the Scan Electron Microscope. The RBS spectra were collected in channelling geometry with incident particles energy 2 MeV and 3.5 MeV. The thickness and the stoichiometric value of the thin films have been evaluated. Simulation of all spectra indicates a constant composition. Ellipsometry method is well adapted to model the thin film structure layers, and to measure the thickness of the film and the complex index of refraction. The theoretical ellipsometric value of the index of refraction is (2.22) while the experimental value is ranging from 2.2 to 2.3 for a wavelength of 1550nm.

The pK0Σ+ final state in proton-proton collisions

“…These data supplement earlier studies on the reaction channels pp → ppω [37,38], pp → pK + Λ, and pp → pK + Σ 0 [10]. As the data for these various reactions were taken simultaneously and the analyses utilized the same software package [39] the results obtained are characterized by a very high degree of internal consistency.…”

“…The acceptance for both channels is about 1.5% with respect to the pK 0 Σ + channel. Considering the total cross sections for the Λ and Σ 0 channels [10] their added contribution to the final event sample is below 15% for each of the three measured beam momenta.…”

“…These features allow the study of different reaction channels (e.g. pp → pp [45], ppγ [46], ppη [47], dπ + [39], ppω [38], pK 0 Σ + [21], and pK + Λ as well as pK + Σ 0 [10]) from the same data sample by examining the measured time-offlight of the charged particles and the overall event topology.…”

“…Various experimental groups have contributed data to the final states pK + Λ, pK + Σ 0 , and nK + Σ + in the past decade [1,2,3,4,5,6,7,8,9,10,11,12]. In all these three cases the final states contain a rather long-lived charged kaon (cτ K + = 3.7 m) and a nucleon, and thus are experimentally well suited to be accessed in inclusive and exclusive measurements at the COSY facility.…”

“…In the case of Λ and Σ 0 production this effort has led to excitation functions measured at excess energies (ǫ = √ s − (m p + m K + m Y )) from only a few MeV above the threshold to ǫ ≈ 250 MeV. Dalitz plots were investigated by the COSY-TOF collaboration [6,9] which, very recently, also published differential cross section data for both reaction channels [10]. Along with the wealth of data, various theoretical approaches based on very different footings were proposed [13,14,15,16,17,18,19].…”