Date 2022-05-10 
Time 16:00 
Title 차세대 정보소자용 스핀트로닉스: 고전에서 양자로 

학과 정기 세미나 안내

■ 제 목:  차세대 정보소자용 스핀트로닉스: 고전에서 양자로 


 연 사:  이경진 교수 (KAIST 물리학과)                  


■  일 시:  2022년 5월 10(화) 오후 4시 


 ■ Host :  박병국 교수 


■ 참가자 접속정보 (3:50분까지 참가를 부탁드립니다)        

               (pw: kaistmse1)
 Abstract :   
Compensated ferrimagnets combine the best features of antiferromagnets and ferromagnets [1]. Antiferromagnets are of considerable interest because the exchange torques between the two sublattices give a time scale that is much faster than that in ferromagnets and the lack of magnetization and net angular momentum lead to minimal perturbation by stray fields and eased constraints due to angular momentum conservation. A compensated ferrimagnet has all these virtues. At the same time, the lack of symmetry between the two sublattices in a compensated ferrimagnet means that quantities like average spin currents are not zero making the systems potentially easier to manipulate and detect the consequences. We will describe calculations and measurements of domain wall and skyrmion motion at the angular momentum compensation point. At this point with no net spin density, the rotational motion of the magnetic textures (domain walls and skyrmions) is absent. As a result, domain walls move fast [2,3], the skyrmion Hall effect vanishes [4], the magnon-photon coupling enhances [5], and a relativistic domain wall motion is realized [2,6]. We will also discuss the increased efficiency of spin torques due to the weakened dephasing in compensated ferrimagnets. Combining experiments with theoretical studies, Refs. [7] and [8] show large torques for ferrimagnetic multilayers and for ferrimagnetic domain walls, respectively
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  2. T. Shiino et al., Antiferromagnetic domain wall motion driven by spin-orbit torques. Phys. Rev. Lett. 117, 087203 (2016).
  3. K.-J. Kim et al., Fast domain wall motion in the vicinity of the angular momentum compensation temperature of ferrimagnets. Nat. Mater. 16, 1187 (2017).
  4. Y. Hirata et al., Vanishing skyrmion Hall effect at the angular momentum compensation temperature of a ferrimagnet. Nat. Nanotechnol. 14, 232 (2019).
  5. J. Shim, S.-J. Kim, S. K. Kim, and K.-J. Lee, Enhanced magnon-photon coupling at the angular momentum compensation point of ferrimagnets. Phys. Rev. Lett. 125, 027205 (2020).
  6. L. Caretta et al., Relativistic kinematics of a magnetic soliton. Science 370, 1438 (2020).
  7. J. Yu et al., Long spin coherence length and bulk-like spin-orbit torque in ferromagnetic multilayers. Nat. Mater. 18, 29 (2019).
  8. T. Okuno et al., Spin-transfer torques for domain wall motion in antiferromagnetically coupled ferrimagnets. Nat. Electron. 2, 372 (2019).