The magnetic and magneto-optial properties of rf sputter-deposited layer-modulated Co/Pt multilayers with Cu and Ag interlayers were investigated. The multilayers in which each Co layer is sandwiched between Pt layers exhibit perfect squareness in the polar Kerr hysteresis. In the Co/Pt multilayers with Cu interlayers, the Kerr rotation angle has a maximum at a wavelength of 600 nm for 50Å Cu thickness.
This paper describes the design and the development of a prefabricated magnetically-shielded-room (PMSR) of the hexagonal type for high sensitive measurement of neuro-magnetic fields such as magnetoencephalography (MEG) mainly using SQUIDs with first and/or second-order gradiometers. This PMSR consists of prefabricated plywood panels 1.2 m wide×2.4 m high×24 mm thick. It covers a floor area of about 9 m2. The panel is sandwiched by two layers of high-μ metal sheets 1 mm thick. The shielding factor at the center of PMSR against the external magnetic field is 20 to 40 dB in the range of DC to 120 Hz. Magnetic noise inside PMSR measured by a second-order gradiometer was less than hundreds fT above 0.5 Hz excepting 50 Hz. In this case, a second order gradiometer was able to eliminate the common mode magnetic noise of about 20 Hz, which was essentially observed by a magnetometer, caused by the vibration of PMSR. These results were discussed and compared with the calculations.
Magnetic and recording characteristics of a Co-Cr/Ni-Fe double-layered tape medium for perpendicular magnetic recording were investigated. The Co-Cr/Ni-Fe tape medium was prepared by the Facing Targets Sputtering (FTS) system on 10-μm-thick polyimide film. The requirements of the Co-Cr/Ni-Fe tape medium for use in a VTR system, such as softness and μi of the Ni-Fe layer, were examined. In order to improve the μi of a Co-Cr/Ni-Fe tape medium, which is decreased by magnetic interaction between the Ni-Fe layer and the Co-Cr recording layer, a 0.03-μm-thick Co67Cr33 interlayer with a small Ms of 51 emu/cc was prepared. Recording and reproducing experiments using a helical-scan VTR machine were carried out on the Co-Cr/Ni-Fe tape medium. Reproduced output of 115 nVo-p/(μm・T・m/s) at a low linear density and a CN ratio at 61 kFRPI of 51.4 dB (R. B. W. = 10 kHz) were obtained by using a TRF head with a 0.2-μm-thick main pole.