The requirement is completely depending on the application. 

Thank you Sir

what about spintronics application for the MTJ?

For spintronic applications, either you need expitaxial film with PMA or ultathin films of CoFeB with PMA. Even the increase of thickness changes the PMA to in-plane anisotropy and makes it difficult for MTJ application.

Sir, can pollycrystalline film give PMA?

For a film which gives PMA, it does not matter whether the film is pollycrystalline or crystalline?

As far as I know, PMA has nothing to do with the crystallinity of the film. You will find most of the Co films with PMA are grown in Si substrates. Co shows polycrystalline nature on Si substrates. The only thing which is very important to form PMA is the thickness of the film. It needs to be ultrathin and in the region of less than 1 nm or so. 

Thank you Sir,

I am wondering that how a pollycrystalline film can give magnetization direction. Could you please clarify it?

Dear Prof. Perumal Alagarsamy,

Could you elaborate more about why utrathin (how thin?) film are good for MTJ and how the PMA changes with changing the film thickness?

Thank you