Superconductivity in an Einstein Solid AxV2Al20 (A = Al and Ga)

Abstract

A cage compound AxV2Al20 (Al10V), that was called an Einstein solid by Caplin and coworkers 40 years ago, is revisited to investigate the low-energy, local vibrations of the A atoms and their influence on the electronic and superconducting properties of the compound. Polycrystalline samples with A = Al, Ga, Y, and La are studied through resistivity and heat capacity measurements. Weak-coupling BCS superconductivity is observed below Tc = 1.49, 1.66, and 0.69 K for Ax = Al0.3, Ga0.2, and Y, respectively, but not above 0.4 K for Ax = La. Low-energy modes are detected only for A = Al and Ga, which are approximately described by the Einstein model with Einstein temperatures of 24 and 8 K, respectively. A weak but significant coupling between the low-energy modes, which are almost identical to those called rattling in recent study, and conduction electrons manifests itself as anomalous enhancement in resistivity at around low temperatures corresponding to the Einstein temperatures.

12 pages, 5 figures, to be published in J. Phys. Soc. Jpn

References in corpus (2)

• Extremely strong-coupling superconductivity and anomalous lattice properties in the beta-pyrochlore oxide KOs2O6
• Rattling-Induced Superconductiviy in the Beta-Pyrochlore Oxides AOs2O6

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• Crystal structure and low-energy Einstein mode in ErV${}_2$Al${}_{20}$ intermetallic cage compound
• Synthesis and properties of A${}_x$V${}_2$Al${}_{20}$ (A = Th, U, Np, Pu) ternary actinide aluminides
• Superconductivity in Cage Compounds La$T{r}_2$Al${}_{20}$ with $Tr$ = Ti, V, Nb, and Ta
• Large Diamagnetism of AV2Al20 (A = Y and La)
• Novel K Rattling: A New Route to Thermoelectric Materials?
• Structural Trends and Itinerant Magnetism of the New Cage-structured Compound HfMn${}_2$Zn${}_{20}$
• Novel Rattling of K Atoms in Aluminium-Doped Defect Pyrochlore Tungstate