Contiguous 3d and 4f Magnetism: strongly correlated 3d electrons in YbFe2Al10

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Date
2014
Authors
Khuntia, P.
Peratheepan, P.
Strydom, A. M.
Utsumi, Y.
Tsuei, K. D.
Tjeng, L. H.
Steglich, F.
Baenitz, M.
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Physical Review
Abstract
We present magnetization, specific heat, and 27 Al NMR investigations on YbFe 2 Al 10 over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a ln ( T 0 / T ) divergence of the low- T specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard-x-ray photoemission spectroscopy study, the Yb valence at 50 K is evaluated to be 2.38. The system displays valence fluctuating behavior in the low to intermediate temperature range, whereas above 400 K, Yb 3 + carries a full and stable moment, and Fe carries a moment of about 3.1 μ B . The enhanced value of the Sommerfeld-Wilson ratio and the dynamic scaling of the spin-lattice relaxation rate divided by T [ 27 ( 1 / T 1 T ) ] with static susceptibility suggests admixed ferromagnetic correlations. 27 ( 1 / T 1 T ) simultaneously tracks the valence fluctuations from the 4 f Yb ions in the high temperature range and field dependent antiferromagnetic correlations among partially Kondo screened Fe 3 d moments at low temperature; the latter evolve out of an Yb 4 f admixed conduction band. DOI: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.216403
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