Magnetic properties of Co/Pd and Co/Pt multilayers were studied as a function of sputtering gas pressure. It was found that the magnetic properties of the films depended upon the sputtering gas pressure, and large coercivity (several kOe) and a perfect squareness of the perpendicular hysteresis loop were attained by the deposition at the high gas pressure. These multilayers are suitable for perpendicular magnetic recording media. In the Co/Pd, the origin of the perpendicular magnetic anisotropy is mainly an interfacial anisotropy, although there exists a stress‐induced anisotropy for the films with the relatively short periodicity. The perpendicular magnetic anisotropy of the Co/Pt can be concerned with the Co‐Pt mixture formed at the interface of the multilayer structure. The magnetostriction of the Co/Pd films with the relatively short periodicity is extraordinarily large with a negative sign, since Co atoms adjacent to Pd atoms at the interface could induce larger magnetostriction than that of pure Co....

Perpendicular magnetic anisotropy and magnetostriction of sputtered Co/Pd and Co/Pt multilayered films

Damping is a critical design parameter for miniaturized mechanical resonators used in microelectromechanical systems (MEMS), nanoelectromechanical systems (NEMS), optomechanical systems, and atomic force microscopy for a large and diverse set of applications ranging from sensing, timing, and signal processing to precision measurements for fundamental studies of materials science and quantum mechanics. This paper presents an overview of recent advances in damping from the viewpoint of device design. The primary goal is to collect and organize methods, tools, and techniques for the rational and effective control of linear damping in miniaturized mechanical resonators. After reviewing some fundamental links between dynamics and dissipation for systems with small linear damping, we explore the space of design and operating parameters for micromechanical and nanomechanical resonators; classify the mechanisms of dissipation into fluid–structure interactions (viscous damping, squeezed-film damping, and acoustic radiation), boundary damping (stress-wave radiation, microsliding, and viscoelasticity), and material damping (thermoelastic damping, dissipation mediated by phonons and electrons, and internal friction due to crystallographic defects); discuss strategies for minimizing each source using a combination of models for dissipation and measurements of material properties; and formulate design principles for low-loss micromechanical and nanomechanical resonators.

https://link.springer.com/content/pdf/10.1186%2Fepjti5.pdf

Design strategies for controlling damping in micromechanical and nanomechanical resonators

Mechanical properties of and cracks and wrinkles in vacuum-deposited MgF2, carbon and baron coatings☆

The vibrating reed technique applicable to the elasticity measurements for the metallic films of nm thickness deposited onto reed substrates and its application to vacuum-deposited aluminium films are reported: Young's modulus of the aluminium films EA1,f shows a good agreement with that of bulk aluminium EA1,b for films of thickness d > 100 nm. For smaller d, FA1,f decreases from EA1,b with decreasing d, especially for d < 10 nm. The decrease in EA1,f is tentatively attributed to the increasing, effects of interfaces between crystallites in the films. The results of internal fricition observed for films of about 50 nm thickness are very similar to those for the films of 100 nm reported by Berry, i.e. the strong decrease in the peak temperatures of the so-called grain-boundary relaxations is observed.



Die „vibrating-reed” Technik in Anwendung auf elastische Messungen an Metallschichten im Dickenbereich von nm, die auf zungenformige Substrate aufgebracht wurden, sowie ihre Anwendung auf vakuumaufgedampfte Aluminiumschichten werden mitgeteilt: der Young-Modul der Aluminium-schichten EA1,f, ist fur Schichten mit d > 100 nm in guter Ubereinstimmung mit dem fur massives Aluminium EA1,b. Fur kleinere d-Werte nimmt EA1,f mit abnehmendem d, insbesondere fur d < 10 nm, gegenuber EA1,b ab. Die Abnahme wird versuchsweise dem zunehmenden Effekt der Grenzflachen zwischen den Kristalliten in den Schichten zugeschrieben. Die Ergebnisse fur die innere Reibung fur etwa 50 nm dicke Schichten sind den von Berry fur 100 nm dicke Schichten beschriebenen sehr ahnlich, d. h. es wird eine starke Abnahme der Temperaturen des sogenannten Korngrenzenrelaxations-maximums beobachtet.

The Elasticity Measurements of Aluminium nm‐Films

Young’s modulus (Ef), magnetostriction (λf), stress (σ), and stress‐induced anisotropy (Ks) were measured in Co/Cu, Fe/Cu, Co/Ag, Co/Pd, and Co/Au compositionally modulated multilayer films (CMF) prepared by rf sputtering method. The measured values of Ef are almost equivalent to those of noble metals of Cu, Ag, Pd, and Au, respectively. The values of λf have an order of 10−5–10−6 which is the same order of the values in Co and Fe films. The calculated values of Ks from these results are about 10 to 100 times smaller than the measured values of perpendicular anisotropy (Ku) in the CMFs. Consequently, these results suggest that Ku of transition metal/noble metal CMFs cannot be explained only in terms of the stress‐induced anisotropy.

Magnetostriction of 3d‐transition metal/noble metal compositionally modulated multilayer films

Internal friction of vacuum‐deposited silver films 2–4 μm thick was measured using the vibrating‐reed method below room temperature in the frequency range 100–400 Hz. Two distinct relaxation peaks were observed, one at around 50 K and the other at around 140 K. The former has been identified as the Bordoni peak, which was very stable against annealing at temperatures as high as 500 °C. The latter is considered as one of the Hasiguti peaks, which completely disappeared through annealing at 400 °C.

K. Uozumi

Papers

Internal friction of vacuum‐deposited silver films