Ikuo Saitoh - Academia.edu (original) (raw)

Papers by Ikuo Saitoh

Applied Optics, 2005

A three-dimensional fourth-order finite-difference time-domain (FDTD) program with a symplectic i... more A three-dimensional fourth-order finite-difference time-domain (FDTD) program with a symplectic integrator scheme has been developed to solve the problem of light scattering by small particles. The symplectic scheme is nondissipative and requires no more storage than the conventional second-order FDTD scheme. The total-field and scattered-field technique is generalized to provide the incident wave source conditions in the symplectic FDTD (SFDTD) scheme. The perfectly matched layer absorbing boundary condition is employed to truncate the computational domain. Numerical examples demonstrate that the fourth-order SFDTD scheme substantially improves the precision of the near-field calculation. The major shortcoming of the fourth-order SFDTD scheme is that it requires more computer CPU time than a conventional second-order FDTD scheme if the same grid size is used. Thus, to make the SFDTD method efficient for practical applications, one needs to parallelize the corresponding computational code.

Magnetics Ieee Transactions on, Mar 1, 1997

電子情報通信学会技術研究報告 Mr 磁気記録, Jan 21, 1999

We proposed a new method, implicit symplectic finite difference time domain (FDTD) method) which ... more We proposed a new method, implicit symplectic finite difference time domain (FDTD) method) which inherits the good properties from the conventional FDTD method, simplecticity and the conservation of energy. The proposed method is free from the Courant-Friedrics-Lewy condition at the same time.In this paper, we show our method is more efficient than the conventional FDTD method using a typical problem, a polarization control in optical near and far fields of the designing the shape of a metal nanostructure.

Journal of the Magnetics Society of Japan, 1994

Physica B: Condensed Matter, 2000

The relation between the material interface of a magnetoresistive (MR) sensor and the stability o... more The relation between the material interface of a magnetoresistive (MR) sensor and the stability of its response is investigated. The cause of the hysteresis in the response of an MR sensor to an applied "eld is investigated using numerical models (a micromagnetic slope model and a micromagnetic step model). Vortex formation is found in the MR sensor. This vortex formation is investigated further by means of an analytical method (Ginzburg}Landau model).

Physica B: Condensed Matter, 2001

The effects of head-medium interaction on the recording characteristics, average amount of magnet... more The effects of head-medium interaction on the recording characteristics, average amount of magnetization recorded and amount of non-linear bit shift, were estimated by means of a newly developed numerical method, based on a micromagnetic model of a thin film and a three-dimensional self-consistent finite element analysis, that takes into account head-medium interaction and head saturation.

IEEE Transactions on Magnetics, 1996

IEEE Transactions on Magnetics, 1994

A new formulation of the threedimensional nonlinear magnetostatic problem is presented. This is a... more A new formulation of the threedimensional nonlinear magnetostatic problem is presented. This is a perturbed h-method without the Lagrange multiplier. To verify this method, the benchmark problem 13 defined in the TEAM Workshop for a nonlinear magnetostatic problem is solved and the results are compared with the experimental results measured by T. Nakata et al. of Okayama University. Also the practical problem of determining the magnetic field excited by a nonuniform sense current of an MR head is solved.

IEEE Transactions on Magnetics, 1997

The magnetoresistive (MR) response of an MR sensor with shields to a uniform applied field was ca... more The magnetoresistive (MR) response of an MR sensor with shields to a uniform applied field was calculated through a micromagnetic simulation, and the results were compared with those from an MR sensor without shields. A uniform longitudinal field, resulting from boundary pinning by exchangebiased antiferromagnetic films, was applied to the MR films of the two sensors. There are three differences between the MR sensors with and without shields: first, the slope of the MR response with shields near an applied field of zero is smaller than the slope of the response without shields. Second, the response of the shielded MR sensor has no subpeak, while the response of the unshielded MR sensor has a subpeak. Third, the output of the shielded MR sensor hardly decreases in a large field (1000 Oe), while the output of the unshielded MR sensor quickly falls to a small value in a field of 300 Oe. These differences are due to attenuated magnetic fields in the gap between the two shields except near the air bearing surface (ABS).

IEEE Transactions on Magnetics, 2002

IEEE Transactions on Magnetics, 2001