AI Article Synopsis
- - Spin and valley indices are important quantum labels for quasi-particles in two-dimensional materials, crucial for advancing spintronics and valleytronics, with control over these properties being a significant challenge.
- - Researchers have demonstrated that a specific combination of a femtosecond laser light (a "hencomb" pulse) can generate highly pure spin and valley currents in materials like WSe and bilayer graphene, achieving up to 90% and over 75% purity, respectively.
- - The study identifies the frequency of the circular light and the THz light polarization as vital control parameters, paving the way for manipulating spin and valley currents using light on ultrafast timescales.
Article Abstract
Spin and valley indices represent the key quantum labels of quasi-particles in a wide class of two-dimensional materials and form the foundational elements of the fields of spintronics and valleytronics. Control over these degrees of freedom, therefore, remains the central challenge in these fields. Here, we show that femtosecond laser light combining optical frequency circularly polarized pulse and a terahertz (THz) frequency linearly polarized pulse, a so-called "hencomb" pulse, can generate precisely tailored and 90% pure spin currents for the dichalcogenide WSe and >75% pure valley currents for bilayer graphene with gaps greater than 120 millielectron volts (dephasing time, 20 femtoseconds). The frequency of the circular light component and the polarization vector of the THz light component are shown to represent the key control parameters of these pulses. Our results thus open a route toward light control over spin/valley current states at ultrafast times.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10017034 | PMC |
| http://dx.doi.org/10.1126/sciadv.adf3673 | DOI Listing |
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