Can cation vacancy defects induce room temperature ferromagnetism in GaN?

The unique properties of gallium nitride (GaN) crystal, such as a wide band-gap and high thermal conductivity, make it ideal material for electronic and optoelectronic devices. Achieving room temperature (RT) ferromagnetism in GaN becomes crucial. In previous works, gallium vacancy (V_Ga) was expected to be promising for reaching this goal. However, using an accurate hybrid exchange-correlation functional, we show that the largest value of J ₀ is only 3.3 meV at the V_Ga density of 1.28 × 10²¹ cm^-3, corresponding to a Curie temperature of 150 K. This suggests that V_Ga cannot induce RT ferromagnetism at the density lower than that value.