Ultrafast ghost Hall states in a 2d altermagnet
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arXiv
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| Main Authors: | , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866908960002408448 |
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| author | Wu, Ruikai Gill, Deepika Sharma, Sangeeta Shallcross, Sam |
| author_facet | Wu, Ruikai Gill, Deepika Sharma, Sangeeta Shallcross, Sam |
| contents | Two-dimensional materials that exhibit optically active spin and valley degrees of freedom represent one of the most fascinating -- and potentially most technologically useful -- platforms for the ultrafast interaction of light and matter. Here we show, via the example of Cr$_2$SO, that two dimensional altermagnets host valley states controllable by femtosecond laser light: linearly polarized light pulses excite charge at one of two inequivalent valleys, with which valley charge is excited at determined by the polarization vector direction. This underpins a rich spin and valley physics including: (i) valleytronics $-$ the generation of nearly 100$\%$ spin polarized valley currents, as well as (ii) a "ghost Hall" effect $-$ the ultrafast creation of states in which spin and charge currents are orthogonal without invoking Hall physics. Our findings establish 2d altermagents as a platform providing a new route for the control of spin- and charge currents at ultrafast times. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_11361 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Ultrafast ghost Hall states in a 2d altermagnet Wu, Ruikai Gill, Deepika Sharma, Sangeeta Shallcross, Sam Mesoscale and Nanoscale Physics Materials Science Other Condensed Matter Computational Physics Quantum Physics Two-dimensional materials that exhibit optically active spin and valley degrees of freedom represent one of the most fascinating -- and potentially most technologically useful -- platforms for the ultrafast interaction of light and matter. Here we show, via the example of Cr$_2$SO, that two dimensional altermagnets host valley states controllable by femtosecond laser light: linearly polarized light pulses excite charge at one of two inequivalent valleys, with which valley charge is excited at determined by the polarization vector direction. This underpins a rich spin and valley physics including: (i) valleytronics $-$ the generation of nearly 100$\%$ spin polarized valley currents, as well as (ii) a "ghost Hall" effect $-$ the ultrafast creation of states in which spin and charge currents are orthogonal without invoking Hall physics. Our findings establish 2d altermagents as a platform providing a new route for the control of spin- and charge currents at ultrafast times. |
| title | Ultrafast ghost Hall states in a 2d altermagnet |
| topic | Mesoscale and Nanoscale Physics Materials Science Other Condensed Matter Computational Physics Quantum Physics |
| url | https://arxiv.org/abs/2604.11361 |