Effect of Ar-N2 sputtering gas on structure and TMD effect in Co–(Si–N) nanogranular films

We have investigated the effect of N
2
ratio in Ar-N
2
sputtering gas on tunneling magneto-dielectric (TMD) effect in Co
19
–(Si–N)
81
nanogranular films. Co
19
–(Si–N)
81
films were deposited by co-sputtering Co and Si
3
N
4
targets in Ar-x vol.%N
2
mixture gas with different x of 0 to 30. All deposited films have nanogranular structure composed of Co nanogranules with a diameter of 2 ~ 3 nm embedded in Si –N matrix, and we realized TMD effect in the film for x ≥ 3.3. The film deposited in Ar-6.6 vol.%N
2
gas showed the highest TMD response. Moreover, we found the two types of change in both nanostructure and the frequency dependence of TMD effect. This study provides the new way to tailor the frequency response of TMD effect.