The resilience of the exchange bias ($H_{EX}$) in ferromagnet / antiferromagnet bilayers is generally studied in terms of repeated hysteresis loop cycling or by protracted annealing under reversed field (training and long-term relaxation respectively). The stability of $H_{EX}$ is fundamental for practical application of exchange bias systems. In this paper we report measurements of training and relaxation in FeNi films coupled with the antiferromagnet FeMn. We show that $H_{EX}$ suppressed both by training and relaxation was partially recovered as soon as a field cycling for consecutive hysteresis loop measurement was stopped or the magnetization of the ferromagnet was switched back to the biased direction.

포항방사광가속기의 전자빔수명을 연장하기 위한 3차 하모닉 초전도 RF 공동기를 개발하고 있다. 저장링 빔물리 계산에 따르면 3차 하모닉 초전도 RF 공동기를 설치할 경우 점자빔의 수명이 약2.3배 증가하는 것으로 나타났다. 또 이 공동기를 설치할 경우 란다우 (Landau) 감쇄 (damping)에 의한 빔의 안정화도 개선되는 효과가 있다. 본 논문은 이것을 실현하기 위한 초전도 RF 공동기의 전자기장 분포와 고차원 전자장 계산을 통하여 최적의 공동기의 모양 결정과 설계 특성에 대한 것을 보고 하고자 한다.

Multi-layer film of $MgO/(FePt-B)_{50nm}/ MgO$ was deposited on Si(100) substrates by RF magnetron sputtering. The boron chips were uniformly placed oil tile FePt target. The boron content of thin film was found to be about 5, 10, 15, 25 and $33 at\%$ by using a CAMECA SX-51 wavelength dispersive spectroscopy (WDX). It is observed that X-ray diffraction patterns of FePt-B film by post-annealing exhibited a transformation from disordered fcc structure to ordered $Ll_0$ phase with fct structure from around $400^{\circ}C$. By adding B, annealing temperature for ordering is about $200^{\circ}C$ lower than that of pure FePt. This remarkable decrease of the annealing temperature is closely related to the high diffusivities of Fe and Pt associated with the defects caused by movements of B atoms. The maximum coercivity(Hc) for FePt films was found to be ${\~}$13 kOe after annealing at $600^{\circ}C$ for 1hr.