Reduction of magnetic defects and coercivity for Co/Si by introducing rubrene at the interface

Yen-Wei Jhou¹, Jian-Chen Tsai^1*, Jyh-Shen Tsay¹, Cheng-Hsun-Tony Chang², Siang-Yu Sie¹, Chun-Kai Yang¹, Chen-Yuan Hsieh¹, Chih-Ming Lin¹

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan
²Department of Electronic Engineering, Minghsin University of Science and Technology, Hsinchu, Taiwan

* Presenter:Jian-Chen Tsai, email:austin12250804@gmail.com

The enhancement of the coercive force is attributed to the imperfection introduced by rough interface to impede the magnetization reversal and the investigation of magnetic defects is crucial for the performance of such film quality [1,2]. We report herein on a novel method using rubrene combined with Kerr microscopy (KM) that enables the direct, quantitative measurement of magnetic defect density [3]. For Co/Si(100), the formation of both triangular shaped Co islands and a pronounced hcp-Co(0002) peak of x-ray diffraction indicate that nanocrystalline cobalt is formed. The Co(0002) peak decreased after the insertion of a rubrene layer. This result shows that Co tends to be structurally amorphous. The insertion of rubrene for Co/Si(100) inhibits the formation of nanocrystalline cobalt. X-ray reflectometry measurements show a smooth interface for Co/Si(100) as compared to Co/rubrene/Si(100). Experimental evidence from KM images shows that coercive force can be reduced by controlling the magnetic defect density by introducing small amounts of rubrene into the films. Furthermore, direct quantitative measurements of magnetic defects show both a one-dimensional bowing of domain walls and strong defect-domain wall interactions in the films. Controlling the magnetic defects to achieve a reduction in coercive force and enlarging the magnetic domain is valuable for future applications of highly uniform film

Keywords: Co/rubrene/Si(100), rubrene, magnetic defects, Kerr microscopy