First-order magnetic phase transition in (Er, Tb)M{sub 2}(M=Co, Ni) (abstract)
- Centro Brasileiro de Pesquisas Fisicas-CBPF/CNPq, r. Dr. Xavier Sigaud 150, CEP-22290-Rio de Janeiro, RJ (Brazil)
The rare-earth intermetallic compounds RCo{sub 2}, cubic Laves phases, are very suitable to study the magnetism of the 3{ital d}. Depending on the R magnetism we have an induced moment for the Co. For R=Dy, Ho, or Er the magnetic transition is of first order, whereas for Gd and Tb it is of second order. This behavior has been observed in this work by electrical resistivity and dc magnetization measurements in function of concentration in the system {ital Er}{sub 1{minus}{ital x}}Tb{sub {ital x}}Co{sub 2} where the internal field of the nearest R neighbors can induce the Co moment. Magnetization measurements of field cooling (FC) and zero field cooling (ZFC) samples are different for {ital T}{lt}{ital T}{sub c}. This difference collapses for higher applied magnetic fields. The minimum for {ital T} just above {ital T}{sub {ital c}} in {rho} vs {ital T} curves disappears for {ital x}=0.2 with the onset of the second-order transition up to {ital x}=1.0. This minimum can result from the conduction electrons scattering on the spin fluctuations, enhanced by the 4{ital f} moments and the scattering by phonons. The idea of the metamagnetism of Co moments in the origin of this minimum is discarded. From our results we can conclude that a small amount of Tb in ErCo{sub 2} changes the first-order to second-order transition. Since the localization of the Fermi energy in the density of state of the 3{ital d} band is very important, a comparison study has been done with the system {ital Er}{sub 1{minus}{ital x}}Tb{sub {ital x}}Ni{sub 2}. The concentration dependence of the lattice parameter differs a little from Vegard{close_quote}s law. Here we can infer from our results that all the magnetic transitions are second-order type. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 281709
- Report Number(s):
- CONF-951101-; ISSN 0021-8979; TRN: 9608M0097
- Journal Information:
- Journal of Applied Physics, Vol. 79, Issue 8; Conference: 40. conference on magnetism and magnetic materials, Philadelphia, PA (United States), 6-9 Nov 1995; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
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