부산대학교 도서관

We have investigated the effect of N2 fraction $x$ in Ar–N2 sputtering gas on the tunneling magnetodielectric (TMD) effect in Co–(Si–N) nanogranular films. Co–(Si–N) films were deposited by co-sputtering Co and Si3N4 targets in Ar- $x$ vol.%N2 mixture gas with different N2 gas fractions $x$ of 0–30. All deposited films had a nanogranular structure composed of Co nanogranules with a diameter of 1–3 nm embedded in a Si–N matrix. We realized the TMD effect in the films for $x \ge3.3$ , and the film deposited in Ar-6.6 vol.%N2 gas showed the highest dielectric variations in a magnetic field. For $3.3\le x \le10$ , TMD peak frequency $f_{\mathrm {TMD}}$ decreased from 17 to 40 kHz with increasing $x$ because of the increase in intergranular spacing $s$ . On the other hand, for $10 < x \le30$ , $f_{\mathrm {TMD}}$ increased from 40 kHz to 3.3 MHz as $x$ increased since both $s$ in the out-of-plane direction and $\beta $ , which indirectly represents the measure of the distribution of $s$ , decreased. This study provides a new way to tailor the frequency response of the TMD effect.