Coherent energy scale revealed by ultrafast dynamics of UX3 (X = Al, Sn, Ga) single crystals

• Main Authors: Nair, Saritha K., Zhu, J. X., Sarrao, J. L., Taylor, Antoinette J., Chia, Elbert E. M.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Chemistry::Crystallography
• Online Access: https://hdl.handle.net/10356/79898; http://hdl.handle.net/10220/9232
• Institution: Nanyang Technological University

The temperature dependence of relaxation dynamics of UX3 (X = Al, Ga, Sn) compounds is studied using the time-resolved pump-probe technique in reflectance geometry. For UGa3, our data are consistent with the formation of a spin density wave gap as evidenced from the quasidivergence of the relaxation time τ near the Néel temperature TN. For UAl3 and USn3, the relaxation dynamics shows a change from single-exponential to two-exponential behavior below a particular temperature, suggestive of coherence formation of the 5f electrons with the conduction band electrons. This particular temperature can be attributed to the spin fluctuation temperature Tsf, a measure of the strength of Kondo coherence. Our Tsf is consistent with other data such as resistivity and susceptibility measurements. The temperature dependence of the relaxation amplitude and time of UAl3 and USn3 were also fitted by the Rothwarf-Taylor model. Our results show that ultrafast optical spectroscopy is sensitive to c-f Kondo hybridization in the f-electron systems.