Low-frequency impedance and heat capacity of LuFe4Al8

Abstract

Temperature dependences of low-frequency impedance (0–107 Hz) and heat capacity of LuFe4Al8 are studied at low temperature in the intervals 4.5–300 K and 1.5–120 K, respectively. The observed singularities suggest that antiferromagnetic phase ordering occurs at TN=100.5 K. A sharp increase in the resistance is observed at a certain temperature T1<TN below which a negative magnetoresistive effect is detected in a weak magnetic field (H<50 Oe). It is shown that the low- temperature anomalies at T<25 K are associated with the superconducting transition. This is supported by the presence of the Meissner effect, levitation, a decrease in ohmic losses, as well as the influence of a static magnetic field and direct current on the resistance of the compound. A magnetostructural phase transition, which is assumed to occur at T1<TN, may be responsible for the peculiarities observed in the physical properties of LuFe4Al8.

Direct evidence for the occurrence of superconductivity in the magnetic compound YFe4Al8

“…Probably, all these results are attributed to the reduction of the spin-disorder scattering due to the spin alignment improvement in an applied weak magnetic field as it was discussed in [13]. Moreover, existence of the negative magnetoresistance in ReM 4 Al 8 compounds in a weak magnetic fields at temperatures just before the superconducting transition [7,8] supports this suggestion.…”

“…However, weak signs of superconductivity in some of the compounds belonging to this family were discovered only recently in the radio-frequency impedance and heat capacity experiments [7,8]. This is very surprising, because the compounds of this type have a…”

“…However, weak signs of superconductivity in some of the compounds belonging to this family were discovered only recently in the radio-frequency impedance and heat capacity experiments [7,8]. This is very surprising, because the compounds of this type have a complicated magnetic structure and their magnetic ordering is far from a completely compensated antiferromagnetic (AFM) order for which superconductivity may coexist with magnetism.…”

Evidence for superconductivity and a pseudogap in the new magnetic compound PrAg6In6

“…Radio-frequency impedance and heat capacity measurements carried out on several compounds of this family have revealed distinct features in the corresponding characteristics which might be associated with superconductivity in some regions of the samples. Such indications of superconductivity were found in LuFe Al 4 8 , ScFe Al 4 8 , YCr 4 Al 8 , YFe Al 4 8 , and PrAg In 6 6 [1,2]. These compounds crystalize with the comparatively simple tetragonal body-centered structure of space group I /mmm D h 4 4 17 ( , nr.…”

Negative Magnetisation and Absence of Superconductivity in RFe4Al8(R=Lu, Yb) Compounds

“…The opened question is, however, the existence of superconductivity in LuFe 4 Al 8 system with nonmagnetic Lu ions. To clarify the doubts about the superconducting properties of the LuFe 4 Al 8 compound reported earlier [8], we have performed extended investigations using magnetic and microwave absorption measurements.…”