For a memory device (specially with a sandwich structure device) role of thin film thickness is extremely important. It should be in the range of a few nm. The memory behavior of your device will reduce 10,000 times if the thickness of thin film will be in micro meters and subsequently there will be no memory effect if thickness will be in mm.
For reference you can watch the video link below presented by Stanely Williams
https://www.youtube.com/watch?v=bKGhvKyjgLY
For further information on memory device and thin films you can read my newly published articles on memory devices as attached in this answer