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The stray field magnitude and distribution, at sensor level, have been investigated as a function of the thickness of the shield, the presence of a domain wall in the shield, the relative position of the vortex accompanying the wall and its proximity to the Air-Bearing-Surface (ABS). Using micromagnetics, the stray fields at the reader sensor have been simulated while a domain wall moves in a shield near the ABS in a magnetic head. For shield thicknesses from 640 nm to 1280 nm, a range of interest for head design, the domain wall shape is C-shaped with a vortex-like structure on either side of the domain wall that provides flux closure inside the film. For a 5 Oe incidental field, the wall exits at the ABS in less than 20 ns when the wall is between the ABS and the vortex. Average stray fields reached 60 Oe while 100 Oe localized stray fields are observed as the wall exits the ABS. The dynamics of wall motion change when the vortex is between the ABS and the domain wall. A 5 Oe incidental field in a 640 nm thick shield drove the wall toward the ABS, compressing the vortex and creating a blocking structure. An incidental 10 Oe field twisted the wall center magnetization enough to change wall chirality accelerating the wall exit, preventing the blocking structure, and flipping the vortex to the other side of the wall. Average stray fields are 55 Oe with a local maximum of 70 Oe. Similar results occur for a 1280 nm thick shield for a 50e field, with average stray fields of 60 Oe and a local maximum of 100 Oe. Index Terms--Blocking structure, chirality, domain wall, noise, stray field.

Magnitudes and distributions of stray magnetic fields from a single domain wall in a Permalloy film are calculated for film thickness from 10 nm to 2.5 [micro]m, using direct integration of the Landau--Lifshitz--Gilbert equation in a Cartesian lattice. This thickness range supports a Neel wall whose magnetization rotates in the plane of the film, a symmetric Bloch wall whose magnetization rotates out of the plane, and an asymmetric Bloch wall whose magnetization rotates simultaneously in and out of the plane of the film at the surfaces and inside the film, respectively. The stray field magnitude is largest for films with a Neel wall rather than film with a Bloch wall. The stray field magnitude varies linearly with thickness for films with Neel walls. The field distribution has a Neel-dominant character, i.e., it lies in a plane perpendicular to the plane of the wall, parallel to the plane of the film, and is dominated by the tranverse component of the field. For films with a Bloch-type component, the stray field is lower. The field distribution has a Bloch-dominant character, i.e., it lies in a plane perpendicular to the plane of the wall, normal to the plane of film, and is dominated by the normal component of the field. At thickness larger than 1 [micro]m, the stray field appears independent of thickness and is relatively constant at 15 Oe. Index Terms--Bloch domain wall, Neel caps, permalloy, stray field.

Cross-tie walls in permalloy films have been simulated as a function of thickness in the range 10-70 nm using direct integration of the Landau-Lifshitz-Gilbert equation in a Cartesian lattice with periodic boundary conditions along the length of the wall. A cross-tie wall is a Bloch-like transition along the wall for vertical Bloch line (VBL)] between Neel Walls of opposite chirality in a film with in-plane magnetization. This transition is a low-energy state, which allows the long tails of Neel walls to partially close their magnetic flux in the vicinity of the walls. The magnetization configuration of these transitions is either elliptical (vortex) or hyperbolic (antivortex). The pi-VBL transitions are 50 nm in diameter and the distance from each other increases with film thickness. The cross-tie wall energy per unit area was lower than that of a pure Neel or Bloch wall between 15 and 50 nm film thickness. Index Terms--Cross-tie wall, Neel caps, Neel wall, permalloy, symmetric and asymmetric Bloch wall, VBL, wall energy.

The simulation of three-dimensional (3D) magnetization structure of transitions T1and T3 in an 80-nm-thick Permalloy film along with wall transition energies per unit area and transition width is discussed. 256 nm is the width for a T1 transition at the center while 45 nm is the width for the T3 pi-vertical Bloch line (pi-VBL) transition.

Research into the Bloch to Neel wall transition in Permalloy films between 160 nm and 10 nm thickness is presented. It was established that the domain wall widths are directly proportional to the thickness for Bloch walls and inversely proportional to the thickness for Neel walls.

Research into three-dimensional magnetic structures of pi-vertical-Bloch line (VBL) and 2pi-VBL in 80-320-nm-thick Permalloy films is presented. It was established that the pi-VBL energy per unit area is 0.44, 0.20 and 0.30 erg/cm2 in 80, 160 and 320 nm films respectively.

A study was conducted to analyze the dynamic characteristics of an isolated stripe domain attracted to a single rectangular groove on the top surface of a bubble garnet film. A numerical framework based on the Landau-Lifshitz-Gilbert equation was utilized to carry out the analysis. Experimental results indicated that the wall shape becomes highly distorted near the groove and forms head-on walls at the groove corners.

A dynamic of a domain wall mobility in Permalloy films calculated as a function of thickness at 10, 80, and 160 nm, which reflects the structure change of Neel, symmetric Bloch and C-shaped domain walls is presented. This investigation allows a detailed examination of spin precession, wall motion and overall magnetization distortion as the wall is moved in the presence of fields ranging from 0.5 to 5 Oe applied in the easy axis direction.

The effects of a single patterned cross groove structure on a stripe domain pinned underneath one of the grooves are presented. This method is effective as long as the cross groove is etched into the bottom of the stripe stabilization groove, rather than being etched into the top surface of the film.

The resonant cavity imaging biosensor (RCIB) is an optical technique for detecting molecular binding interactions label free at many locations in parallel that employs an optical resonant cavity for high sensitivity. Near-infrared light centered at 1512.5 nm couples resonantly through a Fabry-Perot cavity constructed from dielectric reflectors (Si/SiO2), one of which serves as the binding surface. As the wavelength is swept using a tunable laser, a near-infrared digital camera monitors cavity transmittance at each pixel. A wavelength shift in the local resonant response of the optical cavity indicates binding. Positioning the sensing surface with respect to the standing wave pattern of the electric field within the cavity controls the sensitivity with which the presence of bound molecules is detected. Transmitted intensity at thousands of pixel locations is recorded simultaneously in a 10 s, 5 nm scan. An initial proof-of-principle setup has been constructed. A test sample was fabricated with 25,100-mum wide square features, each with a different density of 1-mum square depressions etched 12 nm into the SiO2 surface. The average depth of each etched region was found with 0.05 nm rms precision. In a second test, avidin, bound selectively to biotin conjugated bovine serum albumin, was detected. [ABSTRACT FROM PUBLISHER]