Antiferromagnets can be more promising for spintronics

Yu-Miin Sheu^1,2*, Y. M. Chang¹, C. P. Chang¹, Y. H. Li¹, K. R. Babu³, G. Y. Guo³, T. Kurumaji⁴, Y. Tokura^5,6

¹Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
²Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu, Taiwan
³Department of Physics and Center for Theoretical Physics, National Taiwan University, Taipei, Taiwan
⁴Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
⁵Center for Emergent Matter Science (CEMS), RIKEN, Wako, Saitama, Japan
⁶Department of Applied Physics and Tokyo College, University of Tokyo, Tokyo, Japan

* Presenter:Yu-Miin Sheu, email:ymsheu@nctu.edu.tw

On-demand optomagnet effect, the counterpart of photoelectric and photocurrent effect, that creates switchable magnetization from zero moment was achieved in polar antiferromagnets in (Fe_1−xZn_x)₂Mo₃O₈ family compounds. The switchable optomagnet effects is tunable with magnetization spanning from −40% to 40% of a saturated magnetization, created from helicity of light that flip spin from colinear antiferromagnets without application of magnetic fields. Neither spin canting nor spin-orbit coupling is a prerequisite in order to observe this effect. However, it requires non-magnetic doping to enhance phase competition between antiferromagnetic and ferrimagnetic states to induce gigantic optomagnet effects and to obtain a stabilized transient magnetization with long lifetime. [1] I will discuss the detail scheme as to how spin-flip can occur without spin-orbit coupling and how gigantic effect can be achieved from phase competition. In addition, we discovered that if the ferromagnetic state becomes the ground state by field cooling or by chemical doping, the gigantic optomagnet effect disappears. This implies that antiferromagnets can be more promising than ferromagnet/ferrimagnet for on-demand spintronics.

Keywords: optomagnet, antiferromagnet, spin-flip, polar, spintronics