Unfortunately, our FLD fabricated samples seems has some issues during FMR tests, these samples are very hard to analyze, most of them got very broad and weak absorption peaks, as the measurement angle decreases from 90° (magnetic field perpendicular to films’ surface as 90°), the signal drift away and the peaks’ FWHM gets wider very quick, we suppose this is caused by strong incoherent magnetic rotations and in these samples.
The graph below was measured at 90°, which can get an un-significant absorption peak located at around 1.75 KOe, as the measurement angle decreases, the peak curve become invisible.
Figure 4-33 Ferromagnetic resonance absorption graph of sample (𝐶𝑢 80𝑛𝑚/𝐶𝑜 25𝑛𝑚)1/Cu/H-Si at 350℃, measured at 90°.
73
Chapter 5 Conclusions
We have successfully used PLD to fabricate epitaxy of FCC Co(100) on Cu(100) / H-Si(100) surface at room temperature and at . In order to grow epitaxy at RT, it is necessary to use higher laser power (around 4.25 J/𝑐𝑚2 ), while grows at high temperature, lower laser power (around 3.07 J/𝑐𝑚2) is enough. No structure was found while growing temperature was above 400 ℃, as monitored by XRD. This could be due to the formations of Cu(111) and amorphous phases.
The orientation relation of the epitaxy is: Si[100] // Cu[110] // Co[110]. This 4-fold structure matches the results of angular resolved LMOKE measurements that the easy and hard axes are found along the Si[110] (which is Co[100] direction) and Si[100] (parallel to Co[110] direction), respectively. We also observed that the RT grown samples exhibit stronger 4-fold crystalline magnetic anisotropy than those of grown at HT. Since higher roughness surface is formed at high temperature, which induces stronger pinning effect. We also found that the structure and magnetic anisotropy of MBE and PLD grown samples are same.
Hysteresis loop also shows, in any case RT series has significant lower saturation field as well as Coercivity than HT series, which RT samples exhibs coercivity and saturation field of 16 Oe and 250 Oe, respectively, while HT samples has coercivity and saturation are 25 Oe, and 1.5 kOe, respectively.
74
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