For this thsis, the applications
of superconducting magtoresistive device are proposed including
the supplementary study on magnetic properties of superconductor
which is necessary to the application as following briefly.
In the study on magnetic properties of ceramic superconductor,
it is found that superconductor resistivity are linearly proportional
to external magnetic density, called magnetic sensing property
or magnetoresistance effect. At Superconductivity Laboratory,
Electronics Research Center, Faculty of Engineering, King Mongkut's
Institute of Technology Chaokhuntaharn Ladkrabang, the principle
has been applied to invent a novel magnetic sensor by using
Yttrium type ceramic high temperature superconductor which is
the first achievement in Thailand. This sensor obtains very
high sensittivity to low magnetic field between 10-5-10-2 T
as well as its low frequency response of 0-500 Hz. Furthermore,
our laboratory also discovered the significant properties ;
for example in alternating magnetic signal, superconducting
magnetic sensor generates output signal of full-wave rectification.
Moreover, superconductor responds to D.C.Hysteresis magnetic
field equally in every direction, called isotropic property.
In addition, superconductor can be memoried by applied magnetic
field which is greater than critical magnetic field, called
magnetic memory effect which leads to D.C.hysteresis phenomenon
in superconducting magnetic sensor. Besides, when alternating
magnetic signal applied to superconducting magnetic sensor with
magnetic memory state, its output obtains half-wave rectification
which appears only with different magnetic pole from the memory
pole. By using the fascinating properties above, there are three
applications of superconducting magnetic sensor introduced here
such as non-contact current mater, nonvolatile memory and superconducting
magnetic source directional finder.
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