Observation of Trapped Flux using Scanning SQUID Microscope with High Magnetic Sensitivity

Tatsuaki Ataka, Kazuo Chinone

Seiko Instruments Inc. 563 Takatsukashin-den Matsudo-shi, Chiba 270-2222, Japan

We have newly developed scanning SQUID microscope using micro DC-SQUID and novel cooling system. Micro DC-SQUID has been fabricated on a 3mmﾅ~3mm Si chip using micro-nano process technology. To realize a sufficient spatial resolution, the one-turn pick-up coil of the SQUID is 2mm in diameter and located at the corner of the Si chip. In order to realize easy and speedy operation, we developed the novel cooling system that is a helium flow thermal conducting type. The sample temperature can be controlled between 4k and 100k.
The scanning SQUID microscope had the highest sensitivity of all magnetic imaging systems. We successfully observed trapped flux image with the scanning SQUID microscope. We will present the scanning SQUID microscope and some experimental results of magnetic imaging.