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تسجيل مستخدم جديدSpin excitations of the correlated semiconductor FeSi probed by THz radiation
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By direct measurements of the complex optical conductivity $sigma( u)$ of FeSi we have discovered a broad absorption peak centered at frequency $ u_{0}(4.2 K) approx 32 cm^{-1}$ that develops at temperatures below 20 K. This feature is caused by spin-polaronic states formed in the middle of the gap in the electronic density of states. We observe the spin excitations between the electronic levels split by the exchange field of $H_{e}=34pm 6 T$. Spin fluctuations are identified as the main factor determining the formation of the spin polarons and the rich magnetic phase diagram of FeSi.
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Iron based narrow gap semiconductors such as FeSi, FeSb2, or FeGa3 have received a lot of attention because they exhibit a large thermopower, as well as striking similarities to heavy fermion Kondo insulators. Many proposals have been advanced, howev
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