Al-27 pulsed nuclear magnetic resonance study of CeAl2

作者：Kang Kihyeok; Lee Moohee^*

来源：Current Applied Physics, 2014, 14(3): 383-388.

DOI：10.1016/j.cap.2013.12.008

• CeAl2
• Al-27 NMR
• Knight shift
• Spin-lattice relaxation rate
• Korringa ratio

The magnetic properties and the electronic structures of a rare-earth aluminum intermetallic compound CeAl2 are investigated by magnetic susceptibility measurements and Al-27 pulsed nuclear magnetic resonance (NMR) techniques. The magnetic susceptibility is strongly temperature-dependent, following a Curie-Weiss law down to similar to 12 K, and shows an antiferromagnetic transition at 4 K. The Al-27 NMR spectra show a typical powder pattern for a nuclear spin I of 5/2 with the second-order nuclear quadrupole interaction at high temperature and an additional large dipolar broadening between the 4f electron spins of cerium and the Al-27 nuclear spins at low temperature. The Al-27 NMR Knight shift follows the same temperature dependence as the magnetic susceptibility, suggesting that the Al-27 NMR Knight shift originates from the transferred hyperfine field of the Ce 4f electron spins with the hyperfine coupling constant of A = +5.7 kOe/mu(B). The spin-lattice relaxation rate 1/T-1 is roughly proportional to temperature, as with most non-magnetic metals at high temperature, and then strongly temperature-dependent, increasing rapidly with a peak near the antiferromagnetic transition temperature and decreasing at lower temperature. The temperature dependence of the Korringa ratio K, however, suggests that the antiferromagnetic spin fluctuation signature, which is an enhancement in the Korringa ratio, is washed out owing to the geometrical cancellation of Ce 4f fluctuations at the Al sites.

• 出版日期2014-3