Nonresonant nonlinear magnonics in an antiferromagnet
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arXiv
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2024
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| author | Zhang, Gu-Feng Haque, Sheikh Rubaiat Ul Kaj, Kelson J. Chen, Xiang Seifert, Urban F. P. Zhang, Jingdi Cremin, Kevin A. Balents, Leon Wilson, Stephen D. Averitt, Richard D. |
| author_facet | Zhang, Gu-Feng Haque, Sheikh Rubaiat Ul Kaj, Kelson J. Chen, Xiang Seifert, Urban F. P. Zhang, Jingdi Cremin, Kevin A. Balents, Leon Wilson, Stephen D. Averitt, Richard D. |
| contents | Antiferromagnets exhibit rapid spin dynamics in a net zero magnetic background which enables novel spintronic applications and interrogation of many-body quantum phenomena. The layered antiferromagnet Sr$_2$IrO$_4$ hosts an exotic spin one-half Mott insulating state with an electronic gap arising from on-site Coulomb repulsion and strong spin-orbit coupling. This makes Sr$_2$IrO$_4$ an interesting candidate to interrogate dynamical attributes of the magnetic order using ultrafast laser pulses. We investigate the magnetization dynamics of Sr$_2$IrO$_4$ following circularly-polarized photoexcitation with below-gap mid-infrared (mid-IR -- 9 $μm$) and above-gap near-infrared (near-IR -- 1.3 $μm$) pulses. In both cases, we observe excitation of a zone-center coherent magnon mode featuring a 0.5 THz oscillation in the pump-induced Kerr-rotation signal. However, only below-gap excitation exhibits a helicity dependent response and linear (quadratic) scaling of the coherent magnon amplitude with excitation fluence (electric field). Moreover, below-gap excitation has a magnon generation efficiency that is at least two orders of magnitude greater in comparison to above-gap excitation. Our analysis indicates that the helicity dependence and enhanced generation efficiency arises from a unique one-photon two-magnon coupling mechanism for magnon generation. Thus, preferential spin-photon coupling without photoexcitation of electrons permits extremely efficient magnon generation. Our results reveal new possibilities for ultrafast control of antiferromagnets. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_10579 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Nonresonant nonlinear magnonics in an antiferromagnet Zhang, Gu-Feng Haque, Sheikh Rubaiat Ul Kaj, Kelson J. Chen, Xiang Seifert, Urban F. P. Zhang, Jingdi Cremin, Kevin A. Balents, Leon Wilson, Stephen D. Averitt, Richard D. Strongly Correlated Electrons Antiferromagnets exhibit rapid spin dynamics in a net zero magnetic background which enables novel spintronic applications and interrogation of many-body quantum phenomena. The layered antiferromagnet Sr$_2$IrO$_4$ hosts an exotic spin one-half Mott insulating state with an electronic gap arising from on-site Coulomb repulsion and strong spin-orbit coupling. This makes Sr$_2$IrO$_4$ an interesting candidate to interrogate dynamical attributes of the magnetic order using ultrafast laser pulses. We investigate the magnetization dynamics of Sr$_2$IrO$_4$ following circularly-polarized photoexcitation with below-gap mid-infrared (mid-IR -- 9 $μm$) and above-gap near-infrared (near-IR -- 1.3 $μm$) pulses. In both cases, we observe excitation of a zone-center coherent magnon mode featuring a 0.5 THz oscillation in the pump-induced Kerr-rotation signal. However, only below-gap excitation exhibits a helicity dependent response and linear (quadratic) scaling of the coherent magnon amplitude with excitation fluence (electric field). Moreover, below-gap excitation has a magnon generation efficiency that is at least two orders of magnitude greater in comparison to above-gap excitation. Our analysis indicates that the helicity dependence and enhanced generation efficiency arises from a unique one-photon two-magnon coupling mechanism for magnon generation. Thus, preferential spin-photon coupling without photoexcitation of electrons permits extremely efficient magnon generation. Our results reveal new possibilities for ultrafast control of antiferromagnets. |
| title | Nonresonant nonlinear magnonics in an antiferromagnet |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2411.10579 |