Question

why are matter waves not electromagnetic in nature ? explain

Answer 1

Matter waves are quite different from electromagnetic waves.Electromagnetic waves have larger wavelengths.Unlike electromagnetic waves matter waves don't exist in vacuum.Electromagnetic waves are emitted by something.Example light is emitted by a source of light.Matter waves doesn't come out of anything.They are just linked with matter around us.Thats why matter waves cannot be electromagnetic.

Answer 2

There are many differences because of this: A 'matter wave' is (unavoidably) complex valued, unlike a light wave, where the electric and magnetic fields are always real valued. ... (In addition to John Rennie's point - the phase velocity of a matter wave is half its group velocity, while they are the same for light).