Hi

According to De-Broglie, matter waves are the waves which are associated with each moving particle . The matter waves are not electromagnetic in nature.

Two waves are in phase means , two waves are perfectly aligned to each other and have a phase difference of 0

Whereas,
Two waves are out of phase means that one of the two waves is shifted by one-half cycle relative to the other, two waves which are out of phase cancel each other when added together.


Thankyou