The Experts below are selected from a list of 59253 Experts worldwide ranked by ideXlab platform

Yasuna Kawasaki - One of the best experts on this subject based on the ideXlab platform.

Toshinori Ozaki - One of the best experts on this subject based on the ideXlab platform.

Masahiko Hirao - One of the best experts on this subject based on the ideXlab platform.

  • Annealing Effect on acoustic property of fe pt superlattice studied by picosecond ultrasound
    Japanese Journal of Applied Physics, 2010
    Co-Authors: Nobutomo Nakamura, Atsuyoshi Uranishi, Mamoru Wakita, Hirotsugu Ogi, Masahiko Hirao
    Abstract:

    Fe/Pt superlattices deposited on glass substrates were annealed after deposition, and the relationships among Annealing temperature, out-of-plane longitudinal-wave elastic constant, and the attenuation of a GHz longitudinal acoustic pulse propagating in the superlattices were studied using picosecond ultrasound. Picosecond ultrasound generates and detects GHz longitudinal acoustic pulses using ultrashort pulse lights, and is capable of evaluating the acoustic property of a superlattice thinner than 100 nm without touching the specimen. The elastic constant of an as-deposited superlattice was smaller than those of bulk Fe and Pt; it increased as Annealing temperature increased. The attenuation also increased as Annealing temperature increased. The frequency dependence of the attenuation indicated the formation of FePt alloy at interfaces at 300 °C. Thus, we confirmed that the investigation of acoustic properties using picosecond ultrasound can be a powerful tool for evaluating the structural evolution in superlattices.

  • resonant ultrasound spectroscopy for studying Annealing Effect on elastic constant of thin film
    Ultrasonics, 2010
    Co-Authors: Nobutomo Nakamura, Hirotsugu Ogi, Takeo Nakashima, S Oura, Masahiko Hirao
    Abstract:

    In this paper, we study the elastic property of thin films using resonant-ultrasound spectroscopy (RUS). RUS determines the elastic constants of a solid from its resonance frequencies of free vibration. There were two problems to be solved for applying RUS to thin films: accurate measurement of the resonance frequencies and mode identification of each resonance frequency. We solve these problems using the tripod needle transducers and the laser-Doppler interferometry (LDI). In this paper, we describe the RUS/LDI measurement setup we developed, and show the relationship between the elastic constant and Annealing temperature for Cu thin films. Then, we discuss the Effects of recrystallization and recovery on the elastic constant referring the X-ray diffraction measurement.

  • recovery of elastic constant of ultrathin cu films by low temperature Annealing
    Applied Physics Letters, 2008
    Co-Authors: Nobutomo Nakamura, Hirotsugu Ogi, Tomohiro Shagawa, Masahiko Hirao
    Abstract:

    Annealing Effect on the elastic constant of Cu thin films was investigated by acoustic-phonon resonance spectroscopy. Annealing treatment was performed after the deposition in vacuum condition for 30min at various temperatures up to 200°C. It did not cause obvious changes in the x-ray diffraction spectra, but it significantly increased the elastic constant. The elastic constant of the as-deposited Cu film was smaller than that of bulk Cu by 20%, and it recovered to the bulk value by the postAnnealing at 200°C.

Keita Deguchi - One of the best experts on this subject based on the ideXlab platform.

Satoshi Demura - One of the best experts on this subject based on the ideXlab platform.