A nuclear magnetic resonance probe of Fe-Al and Al20V2Eu intermetallics

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Title: A nuclear magnetic resonance probe of Fe-Al and Al20V2Eu intermetallics
Author: Chi, Ji
Abstract: Al -rich Fe -Al systems (FeAl2 , Fe2 Al5 and Fe4Al13 ) and Al20V2Eu have complicated structures with quasicrystal -like features making these materials potentially of interest for magnetic behavior . However , there is not much work on these materials . To study the variety of magnetic properties , we use NMR , magnetic susceptibility , specific heat and other methods in this work . The microscopic electronic and magnetic properties of the Al -rich Fe -Al system and Al20V2Eu have been studied via 27Al NMR at temperatures between 4 and 500 K . The results of spin lattice relaxation rates reveal a pseudogap in Fe4Al13 and Fe2Al5 around the Fermi -level in the density of states . Besides , a square well gap with a width of 2 meV and center at Fermi energy was detected by specific heat measurements in Fe2Al5 . Both Fe4 Al13 and Fe2Al5 are non -magnetic systems with dilute magnetic defects , while FeAl2 is a concentrated local magnetic moment system . In Al20V2Eu , a crossover was observed in NMR , magnetization and transport measurements . Above 40 K , Eu (2+ ) local magnetic moments dominate ; below 40 K , a transition to a Kondo regime is observed , where the Kondo effect leads to the reduction of localized moments due to the formation of a spin -compensated Kondo cloud . With increasing magnetic field , f electrons participate more and more in excitations near the Fermi level and a heavy -Fermion state was observed through specific heat measurements at high magnetic field .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1584
Date: 2009-05-15

Citation

A nuclear magnetic resonance probe of Fe-Al and Al20V2Eu intermetallics. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1584 .

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