• 제목/요약/키워드: induced magnetism

검색결과 30건 처리시간 0.022초

H-induced Magnetism at Stepped Si (100) Surface

  • Lee, Jun-Ho;Cho, Jun-Hyung
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
    • /
    • pp.211-211
    • /
    • 2012
  • Using spin-polarized density-functional theory calculations, we find that the existence of either Peierls instability or antiferromagnetic spin ordering is sensitive to hydrogen passivation near the step. As hydrogens are covered on the terrace, the dangling bond electrons are localized at the step, leading to step-induced states. We investigate the competition between charge and spin orderings in dangling-bond (DB) wires of increasing lengths fabricated on an H-terminated vicinal Si(001) surface. We find antiferromagnetic (AF) ordering to be energetically much more favorable than charge ordering. The energy preference of AF ordering shrinks in an oscillatory way as the wire length increases. This oscillatory behavior can be interpreted in terms of quantum size effects as the DB electrons fill discrete quantum levels.

  • PDF

A First-principles Study on Magnetism of Al Impurity in bcc Fe

  • Rahman, Gul;Kim, In-Gee
    • Journal of Magnetics
    • /
    • 제16권1호
    • /
    • pp.1-5
    • /
    • 2011
  • The magnetism and electronic structure of bcc $Al_1Fe_{26}$ was investigated by means of first-principles calculations with and without spin-orbit coupling (SOC). From the calculated total energy, the SOC corrected system is shown to be approximately 5 meV per atom lower than the SOC uncorrected system. The induced spin magnetic moment at the Al site was -0.125 ${\mu}_B$ without SOC and -0.124 ${\mu}_B$ with SOC. The orbital magnetic moments were calculated to be 0.002 ${\mu}_B$ in [$\overline{1}$00] direction for Al. The electronic structures showed the nearest neighbor antiferromagnetic interaction between Fe and Al to be essential for determining the magnetism of the $Al_1Fe_{26}$ system.

Development of magnetism in armchair graphene nanoribbons with edge functionalizations: A first-principles study

  • Shin, Dongjae;Kim, Yong-Hoon
    • EDISON SW 활용 경진대회 논문집
    • /
    • 제6회(2017년)
    • /
    • pp.376-382
    • /
    • 2017
  • Graphene nanoribbons with zigzag-shaped edge (zGNRs) are predicted to be magnetic insulator at the ground state, attracting significant interest in view of spintronic applications [1]. On the other hand, although they are energetically and thermodynamically more favored than zGNRs [2], graphene nanoribbons with armchair-shaped edge (aGNRs) have been less spotlighted than zGNRs due to the absence of magnetism. Herein, based on the combined density functional theory (DFT) and matrix Green's function (MGF) approach, we consider aGNRs functionalized with various molecular groups, and show that the spin polarizations develop for some of the considered aGNR edge functionalization cases. The origin of the induced magnetism will be discussed within the Lieb's theorem [3]. This work will provide a novel guidance for the development of graphene-based spintronic devices.

  • PDF

Irradiation-induced BCC-phase formation and magnetism in a 316 austenitic stainless steel

  • Xu, Chaoliang;Liu, Xiangbing;Xue, Fei;Li, Yuanfei;Qian, Wangjie;Jia, Wenqing
    • Nuclear Engineering and Technology
    • /
    • 제52권3호
    • /
    • pp.610-613
    • /
    • 2020
  • Specimens of austenitic stainless steel were irradiated with 6 MeV Xe ions to two doses of 7 and 15 dpa at room temperature and 300 ℃ respectively. Then partial irradiated specimens were subsequently thermally annealed at 550 ℃. Irradiation-induced BCC-phase formation and magnetism were analyzed by grazing incidence X-ray diffraction (GIXRD) and vibrating sample magnetometer (VSM). It has been shown that irradiation damage level, irradiation temperature and annealing temperature have significant effect on BCC-phase formation. This BCC-phase changes the magnetic behavior of austenitic stainless steel. The stress relief and compositional changes in matrix are the driving forces for BCC-phase formation in austenitic stainless steel during ion irradiation.

잔류자기와 I 결선에 의한 3상유도전동기 고정자 권선의 극성판별법에 대한 연구 (A Study on the Polarity Discrimination Method of the Stator Windings for 3 Phase Induction Motors based on the Residual Magnetism and I Winding Connection)

  • 최순만
    • 전기학회논문지
    • /
    • 제64권1호
    • /
    • pp.72-77
    • /
    • 2015
  • When connecting 6 lead wires from stator windings to the terminals of 3 phase induction motors for Y or ${\triangle}$ connection, it is feared that the polarities of windings could be reversed each other if the wire tags are lost or erased, resulting in inadmissibly high current to motors in case of starting. To protect motors against such situations, some test procedures are necessary during wire connection which need to be easy ways to electricians without particular tools except a general multi-tester and with less time-consuming in the field. This study focuses on a test measure to satisfy these requirements which is able to provide them a convenient procedure for winding polarity discrimination considering the field condition. Here, the proposed measure utilizes the residual magnetism of the rotor and checks the indication of voltage or current at windings which are induced by the residual flux of rotor when rotating it by hands with 3 stator windings connected in the form of I connection. Principle characteristics and experiment results for this method are analyzed in the view of the effectiveness and applicability for the winding polarity discrimination.