Effect of Pd, Pt, and Co on the superconducting and magnetic ordering temperatures in RNi{sub 2}B{sub 2}C (R = Tm and Er)

Journal Article · Wed Oct 01 04:00:00 EDT 1997 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1997.7306· OSTI ID:570205

Felner, I ^[1]; Schmitt, D; Barbara, B ^[2]

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1. Hebrew Univ., Jerusalem (Israel)
2. Laboratoire de Magnetisme L. Neel, Grenoble (France); and others

We have investigated the nearly isotropic superconducting intermetallic RNi{sub 2-x}M{sub x}B{sub 2}C system (M = Pd, Pt, and Co, x = 0.05-0.2) by complementary experimental techniques. For TmNi{sub 2}B{sub 2}C, T{sub c} = 10.7 K and the antiferromagnetic (AFM) order of the Tm spins develops below T{sub N} = 1.48 K. Pt as a dopant affects T{sub c} very little, whereas, for M = Pd, T{sub c} is reduced to 9.9 and 9.1 K for x = 0.05 and 0.1, respectively. For TmNi{sub 2}B{sub 2}C and TmNi{sub 1.9}Pt{sub 0.1}B{sub 2}C, the H{sub cl} values exhibit a maximum at 3 K. While the AFM transition for TmNi{sub 2}B{sub 2}C at T{sub N} is clearly identified by specific heat measurements, no specific heat anomaly was observed for TmNi{sub 1.9}Pd{sub 0.1}B{sub 2}C down to 0.8 K, indicating that Pd as a dopant drastically reduces T{sub C} and T{sub N} of the system. For ErNi{sub 2}B{sub 2}C, T{sub C} = 10.9 K and T{sub N} = 6.3 K (T{sub C}>T{sub N}). In ErNi{sub 2-x} M{sub x}B{sub 2}C, both Pt and Pd as dopants (x = 0.2) reduce T{sub C} to {approximately}8 K and shift T{sub N} to {approximately} 11 K. For M = Co and x = 0.05 T{sub C} is reduced to 4.8 K and T{sub N} increases to 8.2 K. For higher Co concentrations (x = 0.2 and 0.5), the compounds are not superconducting, and T{sub N} increases to 10.9 and 14.8 K respectively. It appears that for ErNi{sub 2-x}M{sub x}B{sub 2}C (i) for x = 0.2 the same T{sub N} {approximately} 11.K is obtained regardless of M, and that (ii) in contrast to R = Tm, all dopants studied lead to a reduction of T{sub C} and to an increase of T{sub N} of the Er sublattice, thus T{sub C} < T{sub N}. The delicate interplay between superconductivity and AFM in this system is discussed.

• OSTI ID: 570205
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 133; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORON CARBIDES
COBALT CARBIDES
NICKEL CARBIDES
PALLADIUM CARBIDES
PLATINUM CARBIDES
SPECIFIC HEAT
SUPERCONDUCTIVITY
X-RAY DIFFRACTION