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.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1584 |
| Date | 15 May 2009 |
| Creators | Chi, Ji |
| Contributors | Ross, Jr., Joseph H. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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