Ames Laboratory; Physics and Astronomy
Ames Laboratory, Physics and Astronomy
Physical Review B
75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements have been carried out to investigate the magnetic and electronic properties of the filled skutterudite metallic compound SrFe4As12. The temperature dependence of Knight shift K determined by the NQR spectrum under a small magnetic field (≤0.5T) shows the similar temperature dependence of the magnetic susceptibility χ which exhibits a broad maximum at T∗∼50 K. The nuclear spin-lattice relaxation rate divided by temperature 1/T1T increases with decreasing temperature and exhibits a broad maximum at T∼70 K, similar to the case of χ. The temperature dependence of K and 1/T1T is reasonably explained by a simple model where we assume a concave-shaped band structure near the Fermi energy. Based on a Korringa ratio analysis using the T1 and K data, ferromagnetic spin fluctuations are found to exist in SrFe4As12. These results indicate that SrFe4As12 can be characterized to be a metal with ferromagnetic correlations and also the peculiar band structure responsible for the suppression of 1/T1T and K at low temperatures.
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36 MATERIALS SCIENCE
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