|Título||Spin-glass freezing in Kondo-lattice compounds
Theumann, Alba Graciela Rivas de
Magalhaes, Sergio Garcia
Schmidt, Alex Andre
|Abstract||A theory is presented that describes a spin-glass phase at finite temperatures in Kondo-lattice systems with an additional Ruderman–Kittel–Kasuya–Yosida interaction represented by long range, random couplings among localized spins as in the Sherrington–Kirkpatrick (SK) spin-glass model. The problem is studied within the functional integral formalism where the spin operators are represented by bilinear combinations of fermionic (anticommuting) Grassmann variables. The Kondo and spin-glass transitions are both described with the mean-field–like static ansatz that reproduces good results in the two well-known limits. At high temperatures and low values of the Kondo coupling there is a paramagnetic (disordered) phase with vanishing Kondo and spin-glass order parameters. By lowering the temperature, a second order transition line is found at TSG to a spin-glass phase. For larger values of the Kondo coupling there is a second order transition line at roughly Tk to a Kondo ordered state. For T<TSG the transition between the Kondo and spin-glass phases becomes first order.
|Contido em||Physical review. B, Condensed matter and materials physics. New York. Vol. 63, no. 5 (Feb. 2001), 054409 7p.
Vidros de spin
|Tipo||Artigo de periódico
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