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The recently reported magnetic phase diagram ( T N versus de Gennes factor deG) of the body-centered tetragonal RCo 2 B 2 C series indicates that compounds with R=Pr orders at a higher temperature ( T N ≈10.2 K) than that of the isomorphs R=Nd ( T N =3.0 K), Er ( T N =4.0 K), Sm ( T N =6.0 K), Ho ( T N =5.4 K), Dy ( T N =7.8 K) (Rapp, El Massalami, Phys. Rev. B 60 (1999) 3355; El Massalami et al., Phys. Rev. B, submitted). Since the deG of the latter compounds are higher than that of Pr compound, then such non-monotonic evolution of T N with deG deserves further investigations. In that direction, we synthesized and investigated the magnetic phase diagram of the series Pr 1− x Dy x Co 2 B 2 C ( x =0.0, 0.09, 0.13, 0.345, 0.797, 1.0) wherein deG spans the interval from 0.8 ( x =0) to 7.0819 ( x =1). The obtained unit-cell parameters are in excellent agreement with the Vegard's law, demonstrating that the Pr and Dy atoms substitute each other randomly. Magnetic measurements reveal that the saturated magnetic moment (at 2 K and 90 kOe) increases linearly with x ( ∂μ / ∂x ≈4.7(5) μ B ). Furthermore, for x T N ( x ) decreases sharply with x ( ∂T N / ∂x ≈−36(1) K), while for x ⩾ 0.17, T N ( x ) increases as ∂T N / ∂x ≈5.8(1) K. The overall evolution of T N with deG reproduces satisfactorily the behavior of the above cited RCo 2 B 2 C compounds. These results will be discussed in terms of the hybridization between the 4f and the conduction electrons. |
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