MAGNETIC RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To prevent magnetic information from being forged or fraudulently altered by constituting a magnetic recording medium so that its magnetic layer is physically destroyed when a medium is placed under a low temperature environment, and complicating the rewriting of data by a low temperature cooling when MnBi magnetic powder is used. SOLUTION: In the magnetic recording medium having a magnetic layer 3 formed on a nonmagnetic substrate 1, an expansible film 2 by cooling which physically destroys the magnetic layer 3 by cooling expansion is formed between the nonmagnetic substrate 1 and the magnetic layer 3.