1 / 30

Spin texture

Spin texture. Seminar in 8.3, 2019. By Richen Xiong. Contents. 1. Introduction. 2. 1D case-spin superfluidity. 3. 2D case-domain wall. Introduction. Spin texture: Noncolinear spin configuration.

sosebee
Télécharger la présentation

Spin texture

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Spin texture Seminar in 8.3, 2019 By Richen Xiong

  2. Contents 1 Introduction 2 1D case-spin superfluidity 3 2D case-domain wall

  3. Introduction Spin texture: Noncolinear spin configuration. It can be caused by various interactions, like exchange interaction, DMI, dipole interaction, anisotropy, RKKY, etc. Example: Domain walls, vortices, bubbles, skyrmions.

  4. Introduction

  5. Spin transport Electrons can flip their spin at the interface, while transmitting (or absorbing) a magnon. Boundary condition I is directional order parameter

  6. Spin superfluidity Anotherperspective: hydrodynamics of the winding density

  7. Spin superfluidity

  8. Spin superfluidity

  9. Spin superfluidity- experiment

  10. Spin superfluidity- experiment

  11. Background Mn3Sn Large anomalous Hall effect due to non-vanishing Berry curvature in momentum space Domainwall Bloch type Neel type hexagonal antiferromagnet Triangularspinstructure

  12. Result • Reportthree distinct experimental observations: • Planar Hall effect and planar Nernst effect • A transverse magnetic response • the sign of the emergent electric field depends on the history of the magnetic field orientation.

  13. Result: PHE and PNE Appear in a narrow field window. Different parity.

  14. Result: Magnetization

  15. Explanation: Chiral domain wall x

  16. Discussion: Chiral domain wall The inplane tilt of spins generate a magnetic field. The sign of the signal reflect the chirality of the domain wall

  17. Discussion: Chiral domain wall Conclusion: PHE: In bulk the spin orientation of spins inside the wall is mainly set by past history. TM at surface: the spin orientation mainly depends on the magnetic field. 7 times larger 3times larger

  18. Discussion: Chiral domain wall Where the system stock the history information ? The residual domains.

  19. Discussion: Chiral domain wall Temperature dependence:

  20. summary 1、Report a narrow field window where PHE and PNE can be observed. 2、The sign of PHE can be controlled by prior magnetic history, providing a new platform for memory formation

  21. Background- α-Fe2O3 Weak ferromagnetism TM263K TN963K AFM PM AFM weak FM Physical Review B 96, 094426 (2017)

  22. Data Nonlocal device on (0001) film TM ~ 200K TM ~ 175K

  23. analysis Two features to explain: 1, the shape of this curve Below 𝐻_sf , n is perpendicular to μs and the signal is suppressed whilst in the transition region around 𝐻_sf , n has a non-zero projection on μs leading to a pronounced contribution to the signal. As the field is further increased (𝐻 > 𝐻_sf ), the excited magnons adopt a linear polarization, the magnon gap opens and the signal diminishes. 2, hysteretic behavior We can explain this behaviour by the particular geometry where the field is applied along the easy-axis perpendicular to the surface not previously measured for single crystals. This leads to the formation of non-180 domains above the spin-flop transition due to the 3-fold degeneracy of n in the easy-plane phase when H||z. Successive field cycles through the spin-flop transition lead to depinning and annihilation of domains wall

  24. analysis We note that a spin-reorientation for 𝑯 ⊥ 𝐄𝐀 occurs in easy-axis antiferromagnets with a Dzyaloshinskii-Moriya interaction (DMI)||EA And it is a smooth second-order transition, unlike the hysteretic spin-flop transition at 𝐻|| H_sf. This leads to a progressive parallel alignment of n and μs , accompanied by the softening of one magnon mode In contrast to the case H||z, no additional domain structure is formed when H||x, as the equilibrium orientation of n is nondegenerate, leading to the absence of any hysteresis or training effects.

  25. Data Nonlocal device on (1-102) film TM ~ 200K TM ~ 175K

  26. Data (Ge,Mn)Te by MBE Mn doping ~9.1% • Spacing dependence of Rel • Imaging of domains and domain walls (0001) film 100nm (1-102) film 500nm

  27. To analyze the mechanisms that govern the propagation lengths, we consider two factors. The decay of magnons due to magnetic damping leads to an attenuation that is, in the simplest model, independent of the spin structure. Additionally, scattering of magnons is predicted to occur at magnetic domain walls leading to a spin-structure dependent propagation length. X-ray magnetic linear dichroism photoelectron emission (XMLD-PEEM) imaging

  28. Reference: spin superfluidity 1, PHYSICAL REVIEW LETTERS 121, 127701 (2018) 2, E.B. Sonin (2010) Spin currents and spin superfluidity, Advances in Physics, 59:3, 181-255 3, PHYSICAL REVIEW B 99, 104423 (2019) 4, PRL 112, 227201 (2014)5, PHYSICAL REVIEW B 90, 094408 (2014)6, Yuan et al., Sci. Adv. 2018;4:eaat1098 7, J. Appl. Phys. 124, 190901 (2018)

  29. Reference: domain wall 1, NATURE COMMUNICATIONS (2018)9:4653 2, NATURE COMMUNICATIONS (2019)10:3021 3, SciPost Phys. 5, 063 (2018) 4, Ross 2019 arXiv Efficient magnonic transport and domain wall landscape of insulating antiferromagnetic thin films 5, Nature,vol 561, 224 6, Nature Physics volume 11, pages 1022–1026 (2015)

  30. Thank you for listening!

More Related